From 1cf3c7b5a1d2cd0ed992119b7ab4c7ca6c8500f7 Mon Sep 17 00:00:00 2001 From: Piotr Gorski Date: Wed, 12 Mar 2025 14:15:02 +0100 Subject: [PATCH] prjc-cachy Signed-off-by: Piotr Gorski --- Documentation/admin-guide/sysctl/kernel.rst | 9 + Documentation/scheduler/sched-BMQ.txt | 110 + fs/proc/base.c | 2 +- include/asm-generic/resource.h | 2 +- include/linux/sched.h | 40 +- include/linux/sched/deadline.h | 20 + include/linux/sched/prio.h | 22 + include/linux/sched/rt.h | 2 + include/linux/sched/topology.h | 3 +- init/Kconfig | 32 + init/init_task.c | 20 + kernel/Kconfig.preempt | 4 +- kernel/cgroup/cpuset.c | 10 +- kernel/delayacct.c | 2 +- kernel/exit.c | 4 +- kernel/locking/rtmutex.c | 16 +- kernel/locking/ww_mutex.h | 2 + kernel/sched/Makefile | 5 + kernel/sched/alt_core.c | 7645 +++++++++++++++++++ kernel/sched/alt_core.h | 213 + kernel/sched/alt_debug.c | 32 + kernel/sched/alt_sched.h | 1019 +++ kernel/sched/alt_topology.c | 350 + kernel/sched/alt_topology.h | 6 + kernel/sched/bmq.h | 103 + kernel/sched/build_policy.c | 6 + kernel/sched/build_utility.c | 6 + kernel/sched/cpufreq_schedutil.c | 8 + kernel/sched/cputime.c | 10 +- kernel/sched/debug.c | 14 + kernel/sched/idle.c | 2 + kernel/sched/pds.h | 139 + kernel/sched/pelt.c | 6 +- kernel/sched/pelt.h | 8 +- kernel/sched/sched.h | 9 + kernel/sched/stats.c | 4 + kernel/sched/stats.h | 2 + kernel/sched/syscalls.c | 279 +- kernel/sched/topology.c | 30 + kernel/sysctl.c | 15 + kernel/time/posix-cpu-timers.c | 10 +- kernel/time/timer.c | 4 + kernel/trace/trace_osnoise.c | 4 + kernel/trace/trace_selftest.c | 5 + kernel/workqueue.c | 15 + 45 files changed, 10224 insertions(+), 25 deletions(-) create mode 100644 Documentation/scheduler/sched-BMQ.txt create mode 100644 kernel/sched/alt_core.c create mode 100644 kernel/sched/alt_core.h create mode 100644 kernel/sched/alt_debug.c create mode 100644 kernel/sched/alt_sched.h create mode 100644 kernel/sched/alt_topology.c create mode 100644 kernel/sched/alt_topology.h create mode 100644 kernel/sched/bmq.h create mode 100644 kernel/sched/pds.h diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index b2b36d0c3..8b2b48857 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1682,3 +1682,12 @@ is 10 seconds. The softlockup threshold is (``2 * watchdog_thresh``). Setting this tunable to zero will disable lockup detection altogether. + +yield_type: +=========== + +BMQ/PDS CPU scheduler only. This determines what type of yield calls +to sched_yield() will be performed. + + 0 - No yield. + 1 - Requeue task. (default) diff --git a/Documentation/scheduler/sched-BMQ.txt b/Documentation/scheduler/sched-BMQ.txt new file mode 100644 index 000000000..05c84eec0 --- /dev/null +++ b/Documentation/scheduler/sched-BMQ.txt @@ -0,0 +1,110 @@ + BitMap queue CPU Scheduler + -------------------------- + +CONTENT +======== + + Background + Design + Overview + Task policy + Priority management + BitMap Queue + CPU Assignment and Migration + + +Background +========== + +BitMap Queue CPU scheduler, referred to as BMQ from here on, is an evolution +of previous Priority and Deadline based Skiplist multiple queue scheduler(PDS), +and inspired by Zircon scheduler. The goal of it is to keep the scheduler code +simple, while efficiency and scalable for interactive tasks, such as desktop, +movie playback and gaming etc. + +Design +====== + +Overview +-------- + +BMQ use per CPU run queue design, each CPU(logical) has it's own run queue, +each CPU is responsible for scheduling the tasks that are putting into it's +run queue. + +The run queue is a set of priority queues. Note that these queues are fifo +queue for non-rt tasks or priority queue for rt tasks in data structure. See +BitMap Queue below for details. BMQ is optimized for non-rt tasks in the fact +that most applications are non-rt tasks. No matter the queue is fifo or +priority, In each queue is an ordered list of runnable tasks awaiting execution +and the data structures are the same. When it is time for a new task to run, +the scheduler simply looks the lowest numbered queueue that contains a task, +and runs the first task from the head of that queue. And per CPU idle task is +also in the run queue, so the scheduler can always find a task to run on from +its run queue. + +Each task will assigned the same timeslice(default 4ms) when it is picked to +start running. Task will be reinserted at the end of the appropriate priority +queue when it uses its whole timeslice. When the scheduler selects a new task +from the priority queue it sets the CPU's preemption timer for the remainder of +the previous timeslice. When that timer fires the scheduler will stop execution +on that task, select another task and start over again. + +If a task blocks waiting for a shared resource then it's taken out of its +priority queue and is placed in a wait queue for the shared resource. When it +is unblocked it will be reinserted in the appropriate priority queue of an +eligible CPU. + +Task policy +----------- + +BMQ supports DEADLINE, FIFO, RR, NORMAL, BATCH and IDLE task policy like the +mainline CFS scheduler. But BMQ is heavy optimized for non-rt task, that's +NORMAL/BATCH/IDLE policy tasks. Below is the implementation detail of each +policy. + +DEADLINE + It is squashed as priority 0 FIFO task. + +FIFO/RR + All RT tasks share one single priority queue in BMQ run queue designed. The +complexity of insert operation is O(n). BMQ is not designed for system runs +with major rt policy tasks. + +NORMAL/BATCH/IDLE + BATCH and IDLE tasks are treated as the same policy. They compete CPU with +NORMAL policy tasks, but they just don't boost. To control the priority of +NORMAL/BATCH/IDLE tasks, simply use nice level. + +ISO + ISO policy is not supported in BMQ. Please use nice level -20 NORMAL policy +task instead. + +Priority management +------------------- + +RT tasks have priority from 0-99. For non-rt tasks, there are three different +factors used to determine the effective priority of a task. The effective +priority being what is used to determine which queue it will be in. + +The first factor is simply the task’s static priority. Which is assigned from +task's nice level, within [-20, 19] in userland's point of view and [0, 39] +internally. + +The second factor is the priority boost. This is a value bounded between +[-MAX_PRIORITY_ADJ, MAX_PRIORITY_ADJ] used to offset the base priority, it is +modified by the following cases: + +*When a thread has used up its entire timeslice, always deboost its boost by +increasing by one. +*When a thread gives up cpu control(voluntary or non-voluntary) to reschedule, +and its switch-in time(time after last switch and run) below the thredhold +based on its priority boost, will boost its boost by decreasing by one buti is +capped at 0 (won’t go negative). + +The intent in this system is to ensure that interactive threads are serviced +quickly. These are usually the threads that interact directly with the user +and cause user-perceivable latency. These threads usually do little work and +spend most of their time blocked awaiting another user event. So they get the +priority boost from unblocking while background threads that do most of the +processing receive the priority penalty for using their entire timeslice. diff --git a/fs/proc/base.c b/fs/proc/base.c index 0edf14a98..6dce843be 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -515,7 +515,7 @@ static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns, seq_puts(m, "0 0 0\n"); else seq_printf(m, "%llu %llu %lu\n", - (unsigned long long)task->se.sum_exec_runtime, + (unsigned long long)tsk_seruntime(task), (unsigned long long)task->sched_info.run_delay, task->sched_info.pcount); diff --git a/include/asm-generic/resource.h b/include/asm-generic/resource.h index 8874f681b..59eb72bf7 100644 --- a/include/asm-generic/resource.h +++ b/include/asm-generic/resource.h @@ -23,7 +23,7 @@ [RLIMIT_LOCKS] = { RLIM_INFINITY, RLIM_INFINITY }, \ [RLIMIT_SIGPENDING] = { 0, 0 }, \ [RLIMIT_MSGQUEUE] = { MQ_BYTES_MAX, MQ_BYTES_MAX }, \ - [RLIMIT_NICE] = { 0, 0 }, \ + [RLIMIT_NICE] = { 30, 30 }, \ [RLIMIT_RTPRIO] = { 0, 0 }, \ [RLIMIT_RTTIME] = { RLIM_INFINITY, RLIM_INFINITY }, \ } diff --git a/include/linux/sched.h b/include/linux/sched.h index 949b53e0a..4a164ae50 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -811,9 +811,13 @@ struct task_struct { struct alloc_tag *alloc_tag; #endif -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) || defined(CONFIG_SCHED_ALT) int on_cpu; +#endif + +#ifdef CONFIG_SMP struct __call_single_node wake_entry; +#ifndef CONFIG_SCHED_ALT unsigned int wakee_flips; unsigned long wakee_flip_decay_ts; struct task_struct *last_wakee; @@ -827,6 +831,7 @@ struct task_struct { */ int recent_used_cpu; int wake_cpu; +#endif /* !CONFIG_SCHED_ALT */ #endif int on_rq; @@ -835,6 +840,19 @@ struct task_struct { int normal_prio; unsigned int rt_priority; +#ifdef CONFIG_SCHED_ALT + u64 last_ran; + s64 time_slice; + struct list_head sq_node; +#ifdef CONFIG_SCHED_BMQ + int boost_prio; +#endif /* CONFIG_SCHED_BMQ */ +#ifdef CONFIG_SCHED_PDS + u64 deadline; +#endif /* CONFIG_SCHED_PDS */ + /* sched_clock time spent running */ + u64 sched_time; +#else /* !CONFIG_SCHED_ALT */ struct sched_entity se; struct sched_rt_entity rt; struct sched_dl_entity dl; @@ -849,6 +867,7 @@ struct task_struct { unsigned long core_cookie; unsigned int core_occupation; #endif +#endif /* !CONFIG_SCHED_ALT */ #ifdef CONFIG_CGROUP_SCHED struct task_group *sched_task_group; @@ -885,11 +904,15 @@ struct task_struct { const cpumask_t *cpus_ptr; cpumask_t *user_cpus_ptr; cpumask_t cpus_mask; +#ifndef CONFIG_SCHED_ALT void *migration_pending; +#endif #ifdef CONFIG_SMP unsigned short migration_disabled; #endif +#ifndef CONFIG_SCHED_ALT unsigned short migration_flags; +#endif #ifdef CONFIG_PREEMPT_RCU int rcu_read_lock_nesting; @@ -921,8 +944,10 @@ struct task_struct { struct list_head tasks; #ifdef CONFIG_SMP +#ifndef CONFIG_SCHED_ALT struct plist_node pushable_tasks; struct rb_node pushable_dl_tasks; +#endif #endif struct mm_struct *mm; @@ -1621,6 +1646,15 @@ struct task_struct { */ }; +#ifdef CONFIG_SCHED_ALT +#define tsk_seruntime(t) ((t)->sched_time) +/* replace the uncertian rt_timeout with 0UL */ +#define tsk_rttimeout(t) (0UL) +#else /* CFS */ +#define tsk_seruntime(t) ((t)->se.sum_exec_runtime) +#define tsk_rttimeout(t) ((t)->rt.timeout) +#endif /* !CONFIG_SCHED_ALT */ + #define TASK_REPORT_IDLE (TASK_REPORT + 1) #define TASK_REPORT_MAX (TASK_REPORT_IDLE << 1) @@ -2162,7 +2196,11 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) static inline bool task_is_runnable(struct task_struct *p) { +#ifdef CONFIG_SCHED_ALT + return p->on_rq; +#else return p->on_rq && !p->se.sched_delayed; +#endif /* !CONFIG_SCHED_ALT */ } extern bool sched_task_on_rq(struct task_struct *p); diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h index 3a912ab42..269a1513a 100644 --- a/include/linux/sched/deadline.h +++ b/include/linux/sched/deadline.h @@ -2,6 +2,25 @@ #ifndef _LINUX_SCHED_DEADLINE_H #define _LINUX_SCHED_DEADLINE_H +#ifdef CONFIG_SCHED_ALT + +static inline int dl_task(struct task_struct *p) +{ + return 0; +} + +#ifdef CONFIG_SCHED_BMQ +#define __tsk_deadline(p) (0UL) +#endif + +#ifdef CONFIG_SCHED_PDS +#define __tsk_deadline(p) ((((u64) ((p)->prio))<<56) | (p)->deadline) +#endif + +#else + +#define __tsk_deadline(p) ((p)->dl.deadline) + /* * SCHED_DEADLINE tasks has negative priorities, reflecting * the fact that any of them has higher prio than RT and @@ -23,6 +42,7 @@ static inline bool dl_task(struct task_struct *p) { return dl_prio(p->prio); } +#endif /* CONFIG_SCHED_ALT */ static inline bool dl_time_before(u64 a, u64 b) { diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h index 6ab43b4f7..ef1cff556 100644 --- a/include/linux/sched/prio.h +++ b/include/linux/sched/prio.h @@ -19,6 +19,28 @@ #define MAX_PRIO (MAX_RT_PRIO + NICE_WIDTH) #define DEFAULT_PRIO (MAX_RT_PRIO + NICE_WIDTH / 2) +#ifdef CONFIG_SCHED_ALT + +/* Undefine MAX_PRIO and DEFAULT_PRIO */ +#undef MAX_PRIO +#undef DEFAULT_PRIO + +/* +/- priority levels from the base priority */ +#ifdef CONFIG_SCHED_BMQ +#define MAX_PRIORITY_ADJ (12) +#endif + +#ifdef CONFIG_SCHED_PDS +#define MAX_PRIORITY_ADJ (0) +#endif + +#define MIN_NORMAL_PRIO (128) +#define NORMAL_PRIO_NUM (64) +#define MAX_PRIO (MIN_NORMAL_PRIO + NORMAL_PRIO_NUM) +#define DEFAULT_PRIO (MAX_PRIO - MAX_PRIORITY_ADJ - NICE_WIDTH / 2) + +#endif /* CONFIG_SCHED_ALT */ + /* * Convert user-nice values [ -20 ... 0 ... 19 ] * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h index 4e3338103..6dfef878f 100644 --- a/include/linux/sched/rt.h +++ b/include/linux/sched/rt.h @@ -45,8 +45,10 @@ static inline bool rt_or_dl_task_policy(struct task_struct *tsk) if (policy == SCHED_FIFO || policy == SCHED_RR) return true; +#ifndef CONFIG_SCHED_ALT if (policy == SCHED_DEADLINE) return true; +#endif return false; } diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 4237daa5a..3cebd93c4 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -244,7 +244,8 @@ static inline bool cpus_share_resources(int this_cpu, int that_cpu) #endif /* !CONFIG_SMP */ -#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) +#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) && \ + !defined(CONFIG_SCHED_ALT) extern void rebuild_sched_domains_energy(void); #else static inline void rebuild_sched_domains_energy(void) diff --git a/init/Kconfig b/init/Kconfig index 943717103..878335940 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -665,6 +665,7 @@ config TASK_IO_ACCOUNTING config PSI bool "Pressure stall information tracking" + depends on !SCHED_ALT select KERNFS help Collect metrics that indicate how overcommitted the CPU, memory, @@ -876,6 +877,35 @@ config UCLAMP_BUCKETS_COUNT If in doubt, use the default value. +menuconfig SCHED_ALT + bool "Alternative CPU Schedulers" + default y + help + This feature enable alternative CPU scheduler" + +if SCHED_ALT + +choice + prompt "Alternative CPU Scheduler" + default SCHED_BMQ + +config SCHED_BMQ + bool "BMQ CPU scheduler" + help + The BitMap Queue CPU scheduler for excellent interactivity and + responsiveness on the desktop and solid scalability on normal + hardware and commodity servers. + +config SCHED_PDS + bool "PDS CPU scheduler" + help + The Priority and Deadline based Skip list multiple queue CPU + Scheduler. + +endchoice + +endif + endmenu # @@ -941,6 +971,7 @@ config NUMA_BALANCING depends on ARCH_SUPPORTS_NUMA_BALANCING depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY depends on SMP && NUMA && MIGRATION && !PREEMPT_RT + depends on !SCHED_ALT help This option adds support for automatic NUMA aware memory/task placement. The mechanism is quite primitive and is based on migrating memory when @@ -1364,6 +1395,7 @@ config CHECKPOINT_RESTORE config SCHED_AUTOGROUP bool "Automatic process group scheduling" + depends on !SCHED_ALT select CGROUPS select CGROUP_SCHED select FAIR_GROUP_SCHED diff --git a/init/init_task.c b/init/init_task.c index e557f622b..99e59c208 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -72,9 +72,16 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = { .stack = init_stack, .usage = REFCOUNT_INIT(2), .flags = PF_KTHREAD, +#ifdef CONFIG_SCHED_ALT + .on_cpu = 1, + .prio = DEFAULT_PRIO, + .static_prio = DEFAULT_PRIO, + .normal_prio = DEFAULT_PRIO, +#else .prio = MAX_PRIO - 20, .static_prio = MAX_PRIO - 20, .normal_prio = MAX_PRIO - 20, +#endif .policy = SCHED_NORMAL, .cpus_ptr = &init_task.cpus_mask, .user_cpus_ptr = NULL, @@ -87,6 +94,16 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = { .restart_block = { .fn = do_no_restart_syscall, }, +#ifdef CONFIG_SCHED_ALT + .sq_node = LIST_HEAD_INIT(init_task.sq_node), +#ifdef CONFIG_SCHED_BMQ + .boost_prio = 0, +#endif +#ifdef CONFIG_SCHED_PDS + .deadline = 0, +#endif + .time_slice = HZ, +#else .se = { .group_node = LIST_HEAD_INIT(init_task.se.group_node), }, @@ -94,10 +111,13 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = { .run_list = LIST_HEAD_INIT(init_task.rt.run_list), .time_slice = RR_TIMESLICE, }, +#endif .tasks = LIST_HEAD_INIT(init_task.tasks), +#ifndef CONFIG_SCHED_ALT #ifdef CONFIG_SMP .pushable_tasks = PLIST_NODE_INIT(init_task.pushable_tasks, MAX_PRIO), #endif +#endif #ifdef CONFIG_CGROUP_SCHED .sched_task_group = &root_task_group, #endif diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index 18f87e0dd..92522f614 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -134,7 +134,7 @@ config PREEMPT_DYNAMIC config SCHED_CORE bool "Core Scheduling for SMT" - depends on SCHED_SMT + depends on SCHED_SMT && !SCHED_ALT help This option permits Core Scheduling, a means of coordinated task selection across SMT siblings. When enabled -- see @@ -152,7 +152,7 @@ config SCHED_CORE config SCHED_CLASS_EXT bool "Extensible Scheduling Class" - depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF + depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF && !SCHED_ALT select STACKTRACE if STACKTRACE_SUPPORT help This option enables a new scheduler class sched_ext (SCX), which diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 0f910c828..68f1a692e 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -643,7 +643,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) return ret; } -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) && !defined(CONFIG_SCHED_ALT) /* * Helper routine for generate_sched_domains(). * Do cpusets a, b have overlapping effective cpus_allowed masks? @@ -1063,7 +1063,7 @@ void rebuild_sched_domains_locked(void) /* Have scheduler rebuild the domains */ partition_and_rebuild_sched_domains(ndoms, doms, attr); } -#else /* !CONFIG_SMP */ +#else /* !CONFIG_SMP || CONFIG_SCHED_ALT */ void rebuild_sched_domains_locked(void) { } @@ -2949,12 +2949,15 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) goto out_unlock; } +#ifndef CONFIG_SCHED_ALT if (dl_task(task)) { cs->nr_migrate_dl_tasks++; cs->sum_migrate_dl_bw += task->dl.dl_bw; } +#endif } +#ifndef CONFIG_SCHED_ALT if (!cs->nr_migrate_dl_tasks) goto out_success; @@ -2975,6 +2978,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) } out_success: +#endif /* * Mark attach is in progress. This makes validate_change() fail * changes which zero cpus/mems_allowed. @@ -2996,12 +3000,14 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset) mutex_lock(&cpuset_mutex); dec_attach_in_progress_locked(cs); +#ifndef CONFIG_SCHED_ALT if (cs->nr_migrate_dl_tasks) { int cpu = cpumask_any(cs->effective_cpus); dl_bw_free(cpu, cs->sum_migrate_dl_bw); reset_migrate_dl_data(cs); } +#endif mutex_unlock(&cpuset_mutex); } diff --git a/kernel/delayacct.c b/kernel/delayacct.c index dead51de8..8edef9676 100644 --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -149,7 +149,7 @@ int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) */ t1 = tsk->sched_info.pcount; t2 = tsk->sched_info.run_delay; - t3 = tsk->se.sum_exec_runtime; + t3 = tsk_seruntime(tsk); d->cpu_count += t1; diff --git a/kernel/exit.c b/kernel/exit.c index 1dcddfe53..da0df661f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -174,7 +174,7 @@ static void __exit_signal(struct task_struct *tsk) sig->curr_target = next_thread(tsk); } - add_device_randomness((const void*) &tsk->se.sum_exec_runtime, + add_device_randomness((const void*) &tsk_seruntime(tsk), sizeof(unsigned long long)); /* @@ -195,7 +195,7 @@ static void __exit_signal(struct task_struct *tsk) sig->inblock += task_io_get_inblock(tsk); sig->oublock += task_io_get_oublock(tsk); task_io_accounting_add(&sig->ioac, &tsk->ioac); - sig->sum_sched_runtime += tsk->se.sum_exec_runtime; + sig->sum_sched_runtime += tsk_seruntime(tsk); sig->nr_threads--; __unhash_process(tsk, group_dead); write_sequnlock(&sig->stats_lock); diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 697a56d3d..945955cc6 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -365,7 +365,7 @@ waiter_update_prio(struct rt_mutex_waiter *waiter, struct task_struct *task) lockdep_assert(RB_EMPTY_NODE(&waiter->tree.entry)); waiter->tree.prio = __waiter_prio(task); - waiter->tree.deadline = task->dl.deadline; + waiter->tree.deadline = __tsk_deadline(task); } /* @@ -386,16 +386,20 @@ waiter_clone_prio(struct rt_mutex_waiter *waiter, struct task_struct *task) * Only use with rt_waiter_node_{less,equal}() */ #define task_to_waiter_node(p) \ - &(struct rt_waiter_node){ .prio = __waiter_prio(p), .deadline = (p)->dl.deadline } + &(struct rt_waiter_node){ .prio = __waiter_prio(p), .deadline = __tsk_deadline(p) } #define task_to_waiter(p) \ &(struct rt_mutex_waiter){ .tree = *task_to_waiter_node(p) } static __always_inline int rt_waiter_node_less(struct rt_waiter_node *left, struct rt_waiter_node *right) { +#ifdef CONFIG_SCHED_PDS + return (left->deadline < right->deadline); +#else if (left->prio < right->prio) return 1; +#ifndef CONFIG_SCHED_BMQ /* * If both waiters have dl_prio(), we check the deadlines of the * associated tasks. @@ -404,16 +408,22 @@ static __always_inline int rt_waiter_node_less(struct rt_waiter_node *left, */ if (dl_prio(left->prio)) return dl_time_before(left->deadline, right->deadline); +#endif return 0; +#endif } static __always_inline int rt_waiter_node_equal(struct rt_waiter_node *left, struct rt_waiter_node *right) { +#ifdef CONFIG_SCHED_PDS + return (left->deadline == right->deadline); +#else if (left->prio != right->prio) return 0; +#ifndef CONFIG_SCHED_BMQ /* * If both waiters have dl_prio(), we check the deadlines of the * associated tasks. @@ -422,8 +432,10 @@ static __always_inline int rt_waiter_node_equal(struct rt_waiter_node *left, */ if (dl_prio(left->prio)) return left->deadline == right->deadline; +#endif return 1; +#endif } static inline bool rt_mutex_steal(struct rt_mutex_waiter *waiter, diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h index 37f025a09..45ae7a6fd 100644 --- a/kernel/locking/ww_mutex.h +++ b/kernel/locking/ww_mutex.h @@ -247,6 +247,7 @@ __ww_ctx_less(struct ww_acquire_ctx *a, struct ww_acquire_ctx *b) /* equal static prio */ +#ifndef CONFIG_SCHED_ALT if (dl_prio(a_prio)) { if (dl_time_before(b->task->dl.deadline, a->task->dl.deadline)) @@ -256,6 +257,7 @@ __ww_ctx_less(struct ww_acquire_ctx *a, struct ww_acquire_ctx *b) b->task->dl.deadline)) return false; } +#endif /* equal prio */ } diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile index 976092b7b..31d587c16 100644 --- a/kernel/sched/Makefile +++ b/kernel/sched/Makefile @@ -28,7 +28,12 @@ endif # These compilation units have roughly the same size and complexity - so their # build parallelizes well and finishes roughly at once: # +ifdef CONFIG_SCHED_ALT +obj-y += alt_core.o +obj-$(CONFIG_SCHED_DEBUG) += alt_debug.o +else obj-y += core.o obj-y += fair.o +endif obj-y += build_policy.o obj-y += build_utility.o diff --git a/kernel/sched/alt_core.c b/kernel/sched/alt_core.c new file mode 100644 index 000000000..e6e247dec --- /dev/null +++ b/kernel/sched/alt_core.c @@ -0,0 +1,7645 @@ +/* + * kernel/sched/alt_core.c + * + * Core alternative kernel scheduler code and related syscalls + * + * Copyright (C) 1991-2002 Linus Torvalds + * + * 2009-08-13 Brainfuck deadline scheduling policy by Con Kolivas deletes + * a whole lot of those previous things. + * 2017-09-06 Priority and Deadline based Skip list multiple queue kernel + * scheduler by Alfred Chen. + * 2019-02-20 BMQ(BitMap Queue) kernel scheduler by Alfred Chen. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include +#include + +#define CREATE_TRACE_POINTS +#include +#include +#undef CREATE_TRACE_POINTS + +#include "sched.h" +#include "smp.h" + +#include "pelt.h" + +#include "../../io_uring/io-wq.h" +#include "../smpboot.h" + +EXPORT_TRACEPOINT_SYMBOL_GPL(ipi_send_cpu); +EXPORT_TRACEPOINT_SYMBOL_GPL(ipi_send_cpumask); + +/* + * Export tracepoints that act as a bare tracehook (ie: have no trace event + * associated with them) to allow external modules to probe them. + */ +EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); + +#ifdef CONFIG_SCHED_DEBUG +#define sched_feat(x) (1) +/* + * Print a warning if need_resched is set for the given duration (if + * LATENCY_WARN is enabled). + * + * If sysctl_resched_latency_warn_once is set, only one warning will be shown + * per boot. + */ +__read_mostly int sysctl_resched_latency_warn_ms = 100; +__read_mostly int sysctl_resched_latency_warn_once = 1; +#else +#define sched_feat(x) (0) +#endif /* CONFIG_SCHED_DEBUG */ + +#define ALT_SCHED_VERSION "v6.13-r1" + +#define STOP_PRIO (MAX_RT_PRIO - 1) + +/* + * Time slice + * (default: 4 msec, units: nanoseconds) + */ +unsigned int sysctl_sched_base_slice __read_mostly = (4 << 20); + +#include "alt_core.h" +#include "alt_topology.h" + +/* Reschedule if less than this many μs left */ +#define RESCHED_NS (100 << 10) + +/** + * sched_yield_type - Type of sched_yield() will be performed. + * 0: No yield. + * 1: Requeue task. (default) + */ +int sched_yield_type __read_mostly = 1; + +#ifdef CONFIG_SMP +cpumask_t sched_rq_pending_mask ____cacheline_aligned_in_smp; + +DEFINE_PER_CPU_ALIGNED(cpumask_t [NR_CPU_AFFINITY_LEVELS], sched_cpu_topo_masks); +DEFINE_PER_CPU_ALIGNED(cpumask_t *, sched_cpu_llc_mask); +DEFINE_PER_CPU_ALIGNED(cpumask_t *, sched_cpu_topo_end_mask); + +#ifdef CONFIG_SCHED_SMT +DEFINE_STATIC_KEY_FALSE(sched_smt_present); +EXPORT_SYMBOL_GPL(sched_smt_present); + +cpumask_t sched_smt_mask ____cacheline_aligned_in_smp; +#endif + +/* + * Keep a unique ID per domain (we use the first CPUs number in the cpumask of + * the domain), this allows us to quickly tell if two cpus are in the same cache + * domain, see cpus_share_cache(). + */ +DEFINE_PER_CPU(int, sd_llc_id); +#endif /* CONFIG_SMP */ + +DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); + +#ifndef prepare_arch_switch +# define prepare_arch_switch(next) do { } while (0) +#endif +#ifndef finish_arch_post_lock_switch +# define finish_arch_post_lock_switch() do { } while (0) +#endif + +static cpumask_t sched_preempt_mask[SCHED_QUEUE_BITS + 2] ____cacheline_aligned_in_smp; + +cpumask_t *const sched_idle_mask = &sched_preempt_mask[SCHED_QUEUE_BITS - 1]; +cpumask_t *const sched_sg_idle_mask = &sched_preempt_mask[SCHED_QUEUE_BITS]; +cpumask_t *const sched_pcore_idle_mask = &sched_preempt_mask[SCHED_QUEUE_BITS]; +cpumask_t *const sched_ecore_idle_mask = &sched_preempt_mask[SCHED_QUEUE_BITS + 1]; + +/* task function */ +static inline const struct cpumask *task_user_cpus(struct task_struct *p) +{ + if (!p->user_cpus_ptr) + return cpu_possible_mask; /* &init_task.cpus_mask */ + return p->user_cpus_ptr; +} + +/* sched_queue related functions */ +static inline void sched_queue_init(struct sched_queue *q) +{ + int i; + + bitmap_zero(q->bitmap, SCHED_QUEUE_BITS); + for(i = 0; i < SCHED_LEVELS; i++) + INIT_LIST_HEAD(&q->heads[i]); +} + +/* + * Init idle task and put into queue structure of rq + * IMPORTANT: may be called multiple times for a single cpu + */ +static inline void sched_queue_init_idle(struct sched_queue *q, + struct task_struct *idle) +{ + INIT_LIST_HEAD(&q->heads[IDLE_TASK_SCHED_PRIO]); + list_add_tail(&idle->sq_node, &q->heads[IDLE_TASK_SCHED_PRIO]); + idle->on_rq = TASK_ON_RQ_QUEUED; +} + +#define CLEAR_CACHED_PREEMPT_MASK(pr, low, high, cpu) \ + if (low < pr && pr <= high) \ + cpumask_clear_cpu(cpu, sched_preempt_mask + pr); + +#define SET_CACHED_PREEMPT_MASK(pr, low, high, cpu) \ + if (low < pr && pr <= high) \ + cpumask_set_cpu(cpu, sched_preempt_mask + pr); + +static atomic_t sched_prio_record = ATOMIC_INIT(0); + +/* water mark related functions */ +static inline void update_sched_preempt_mask(struct rq *rq) +{ + int prio = find_first_bit(rq->queue.bitmap, SCHED_QUEUE_BITS); + int last_prio = rq->prio; + int cpu, pr; + + if (prio == last_prio) + return; + + rq->prio = prio; +#ifdef CONFIG_SCHED_PDS + rq->prio_idx = sched_prio2idx(rq->prio, rq); +#endif + cpu = cpu_of(rq); + pr = atomic_read(&sched_prio_record); + + if (prio < last_prio) { + if (IDLE_TASK_SCHED_PRIO == last_prio) { + rq->clear_idle_mask_func(cpu, sched_idle_mask); + last_prio -= 2; + } + CLEAR_CACHED_PREEMPT_MASK(pr, prio, last_prio, cpu); + + return; + } + /* last_prio < prio */ + if (IDLE_TASK_SCHED_PRIO == prio) { + rq->set_idle_mask_func(cpu, sched_idle_mask); + prio -= 2; + } + SET_CACHED_PREEMPT_MASK(pr, last_prio, prio, cpu); +} + +/* + * Serialization rules: + * + * Lock order: + * + * p->pi_lock + * rq->lock + * hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls) + * + * rq1->lock + * rq2->lock where: rq1 < rq2 + * + * Regular state: + * + * Normal scheduling state is serialized by rq->lock. __schedule() takes the + * local CPU's rq->lock, it optionally removes the task from the runqueue and + * always looks at the local rq data structures to find the most eligible task + * to run next. + * + * Task enqueue is also under rq->lock, possibly taken from another CPU. + * Wakeups from another LLC domain might use an IPI to transfer the enqueue to + * the local CPU to avoid bouncing the runqueue state around [ see + * ttwu_queue_wakelist() ] + * + * Task wakeup, specifically wakeups that involve migration, are horribly + * complicated to avoid having to take two rq->locks. + * + * Special state: + * + * System-calls and anything external will use task_rq_lock() which acquires + * both p->pi_lock and rq->lock. As a consequence the state they change is + * stable while holding either lock: + * + * - sched_setaffinity()/ + * set_cpus_allowed_ptr(): p->cpus_ptr, p->nr_cpus_allowed + * - set_user_nice(): p->se.load, p->*prio + * - __sched_setscheduler(): p->sched_class, p->policy, p->*prio, + * p->se.load, p->rt_priority, + * p->dl.dl_{runtime, deadline, period, flags, bw, density} + * - sched_setnuma(): p->numa_preferred_nid + * - sched_move_task(): p->sched_task_group + * - uclamp_update_active() p->uclamp* + * + * p->state <- TASK_*: + * + * is changed locklessly using set_current_state(), __set_current_state() or + * set_special_state(), see their respective comments, or by + * try_to_wake_up(). This latter uses p->pi_lock to serialize against + * concurrent self. + * + * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }: + * + * is set by activate_task() and cleared by deactivate_task(), under + * rq->lock. Non-zero indicates the task is runnable, the special + * ON_RQ_MIGRATING state is used for migration without holding both + * rq->locks. It indicates task_cpu() is not stable, see task_rq_lock(). + * + * Additionally it is possible to be ->on_rq but still be considered not + * runnable when p->se.sched_delayed is true. These tasks are on the runqueue + * but will be dequeued as soon as they get picked again. See the + * task_is_runnable() helper. + * + * p->on_cpu <- { 0, 1 }: + * + * is set by prepare_task() and cleared by finish_task() such that it will be + * set before p is scheduled-in and cleared after p is scheduled-out, both + * under rq->lock. Non-zero indicates the task is running on its CPU. + * + * [ The astute reader will observe that it is possible for two tasks on one + * CPU to have ->on_cpu = 1 at the same time. ] + * + * task_cpu(p): is changed by set_task_cpu(), the rules are: + * + * - Don't call set_task_cpu() on a blocked task: + * + * We don't care what CPU we're not running on, this simplifies hotplug, + * the CPU assignment of blocked tasks isn't required to be valid. + * + * - for try_to_wake_up(), called under p->pi_lock: + * + * This allows try_to_wake_up() to only take one rq->lock, see its comment. + * + * - for migration called under rq->lock: + * [ see task_on_rq_migrating() in task_rq_lock() ] + * + * o move_queued_task() + * o detach_task() + * + * - for migration called under double_rq_lock(): + * + * o __migrate_swap_task() + * o push_rt_task() / pull_rt_task() + * o push_dl_task() / pull_dl_task() + * o dl_task_offline_migration() + * + */ + +/* + * Context: p->pi_lock + */ +static inline struct rq * +task_access_lock_irqsave(struct task_struct *p, raw_spinlock_t **plock, unsigned long *flags) +{ + struct rq *rq; + for (;;) { + rq = task_rq(p); + if (p->on_cpu || task_on_rq_queued(p)) { + raw_spin_lock_irqsave(&rq->lock, *flags); + if (likely((p->on_cpu || task_on_rq_queued(p)) && rq == task_rq(p))) { + *plock = &rq->lock; + return rq; + } + raw_spin_unlock_irqrestore(&rq->lock, *flags); + } else if (task_on_rq_migrating(p)) { + do { + cpu_relax(); + } while (unlikely(task_on_rq_migrating(p))); + } else { + raw_spin_lock_irqsave(&p->pi_lock, *flags); + if (likely(!p->on_cpu && !p->on_rq && rq == task_rq(p))) { + *plock = &p->pi_lock; + return rq; + } + raw_spin_unlock_irqrestore(&p->pi_lock, *flags); + } + } +} + +static inline void +task_access_unlock_irqrestore(struct task_struct *p, raw_spinlock_t *lock, unsigned long *flags) +{ + raw_spin_unlock_irqrestore(lock, *flags); +} + +/* + * __task_rq_lock - lock the rq @p resides on. + */ +struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) + __acquires(rq->lock) +{ + struct rq *rq; + + lockdep_assert_held(&p->pi_lock); + + for (;;) { + rq = task_rq(p); + raw_spin_lock(&rq->lock); + if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) + return rq; + raw_spin_unlock(&rq->lock); + + while (unlikely(task_on_rq_migrating(p))) + cpu_relax(); + } +} + +/* + * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. + */ +struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) + __acquires(p->pi_lock) + __acquires(rq->lock) +{ + struct rq *rq; + + for (;;) { + raw_spin_lock_irqsave(&p->pi_lock, rf->flags); + rq = task_rq(p); + raw_spin_lock(&rq->lock); + /* + * move_queued_task() task_rq_lock() + * + * ACQUIRE (rq->lock) + * [S] ->on_rq = MIGRATING [L] rq = task_rq() + * WMB (__set_task_cpu()) ACQUIRE (rq->lock); + * [S] ->cpu = new_cpu [L] task_rq() + * [L] ->on_rq + * RELEASE (rq->lock) + * + * If we observe the old CPU in task_rq_lock(), the acquire of + * the old rq->lock will fully serialize against the stores. + * + * If we observe the new CPU in task_rq_lock(), the address + * dependency headed by '[L] rq = task_rq()' and the acquire + * will pair with the WMB to ensure we then also see migrating. + */ + if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { + return rq; + } + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); + + while (unlikely(task_on_rq_migrating(p))) + cpu_relax(); + } +} + +static inline void rq_lock_irqsave(struct rq *rq, struct rq_flags *rf) + __acquires(rq->lock) +{ + raw_spin_lock_irqsave(&rq->lock, rf->flags); +} + +static inline void rq_unlock_irqrestore(struct rq *rq, struct rq_flags *rf) + __releases(rq->lock) +{ + raw_spin_unlock_irqrestore(&rq->lock, rf->flags); +} + +DEFINE_LOCK_GUARD_1(rq_lock_irqsave, struct rq, + rq_lock_irqsave(_T->lock, &_T->rf), + rq_unlock_irqrestore(_T->lock, &_T->rf), + struct rq_flags rf) + +void raw_spin_rq_lock_nested(struct rq *rq, int subclass) +{ + raw_spinlock_t *lock; + + /* Matches synchronize_rcu() in __sched_core_enable() */ + preempt_disable(); + + for (;;) { + lock = __rq_lockp(rq); + raw_spin_lock_nested(lock, subclass); + if (likely(lock == __rq_lockp(rq))) { + /* preempt_count *MUST* be > 1 */ + preempt_enable_no_resched(); + return; + } + raw_spin_unlock(lock); + } +} + +void raw_spin_rq_unlock(struct rq *rq) +{ + raw_spin_unlock(rq_lockp(rq)); +} + +/* + * RQ-clock updating methods: + */ + +static void update_rq_clock_task(struct rq *rq, s64 delta) +{ +/* + * In theory, the compile should just see 0 here, and optimize out the call + * to sched_rt_avg_update. But I don't trust it... + */ + s64 __maybe_unused steal = 0, irq_delta = 0; + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; + + /* + * Since irq_time is only updated on {soft,}irq_exit, we might run into + * this case when a previous update_rq_clock() happened inside a + * {soft,}IRQ region. + * + * When this happens, we stop ->clock_task and only update the + * prev_irq_time stamp to account for the part that fit, so that a next + * update will consume the rest. This ensures ->clock_task is + * monotonic. + * + * It does however cause some slight miss-attribution of {soft,}IRQ + * time, a more accurate solution would be to update the irq_time using + * the current rq->clock timestamp, except that would require using + * atomic ops. + */ + if (irq_delta > delta) + irq_delta = delta; + + rq->prev_irq_time += irq_delta; + delta -= irq_delta; + delayacct_irq(rq->curr, irq_delta); +#endif +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING + if (static_key_false((¶virt_steal_rq_enabled))) { + steal = paravirt_steal_clock(cpu_of(rq)); + steal -= rq->prev_steal_time_rq; + + if (unlikely(steal > delta)) + steal = delta; + + rq->prev_steal_time_rq += steal; + delta -= steal; + } +#endif + + rq->clock_task += delta; + +#ifdef CONFIG_HAVE_SCHED_AVG_IRQ + if ((irq_delta + steal)) + update_irq_load_avg(rq, irq_delta + steal); +#endif +} + +static inline void update_rq_clock(struct rq *rq) +{ + s64 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; + + if (unlikely(delta <= 0)) + return; + rq->clock += delta; + sched_update_rq_clock(rq); + update_rq_clock_task(rq, delta); +} + +/* + * RQ Load update routine + */ +#define RQ_LOAD_HISTORY_BITS (sizeof(s32) * 8ULL) +#define RQ_UTIL_SHIFT (8) +#define RQ_LOAD_HISTORY_TO_UTIL(l) (((l) >> (RQ_LOAD_HISTORY_BITS - 1 - RQ_UTIL_SHIFT)) & 0xff) + +#define LOAD_BLOCK(t) ((t) >> 17) +#define LOAD_HALF_BLOCK(t) ((t) >> 16) +#define BLOCK_MASK(t) ((t) & ((0x01 << 18) - 1)) +#define LOAD_BLOCK_BIT(b) (1UL << (RQ_LOAD_HISTORY_BITS - 1 - (b))) +#define CURRENT_LOAD_BIT LOAD_BLOCK_BIT(0) + +static inline void rq_load_update(struct rq *rq) +{ + u64 time = rq->clock; + u64 delta = min(LOAD_BLOCK(time) - LOAD_BLOCK(rq->load_stamp), RQ_LOAD_HISTORY_BITS - 1); + u64 prev = !!(rq->load_history & CURRENT_LOAD_BIT); + u64 curr = !!rq->nr_running; + + if (delta) { + rq->load_history = rq->load_history >> delta; + + if (delta < RQ_UTIL_SHIFT) { + rq->load_block += (~BLOCK_MASK(rq->load_stamp)) * prev; + if (!!LOAD_HALF_BLOCK(rq->load_block) ^ curr) + rq->load_history ^= LOAD_BLOCK_BIT(delta); + } + + rq->load_block = BLOCK_MASK(time) * prev; + } else { + rq->load_block += (time - rq->load_stamp) * prev; + } + if (prev ^ curr) + rq->load_history ^= CURRENT_LOAD_BIT; + rq->load_stamp = time; +} + +unsigned long rq_load_util(struct rq *rq, unsigned long max) +{ + return RQ_LOAD_HISTORY_TO_UTIL(rq->load_history) * (max >> RQ_UTIL_SHIFT); +} + +#ifdef CONFIG_SMP +unsigned long sched_cpu_util(int cpu) +{ + return rq_load_util(cpu_rq(cpu), arch_scale_cpu_capacity(cpu)); +} +#endif /* CONFIG_SMP */ + +#ifdef CONFIG_CPU_FREQ +/** + * cpufreq_update_util - Take a note about CPU utilization changes. + * @rq: Runqueue to carry out the update for. + * @flags: Update reason flags. + * + * This function is called by the scheduler on the CPU whose utilization is + * being updated. + * + * It can only be called from RCU-sched read-side critical sections. + * + * The way cpufreq is currently arranged requires it to evaluate the CPU + * performance state (frequency/voltage) on a regular basis to prevent it from + * being stuck in a completely inadequate performance level for too long. + * That is not guaranteed to happen if the updates are only triggered from CFS + * and DL, though, because they may not be coming in if only RT tasks are + * active all the time (or there are RT tasks only). + * + * As a workaround for that issue, this function is called periodically by the + * RT sched class to trigger extra cpufreq updates to prevent it from stalling, + * but that really is a band-aid. Going forward it should be replaced with + * solutions targeted more specifically at RT tasks. + */ +static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) +{ + struct update_util_data *data; + +#ifdef CONFIG_SMP + rq_load_update(rq); +#endif + data = rcu_dereference_sched(*per_cpu_ptr(&cpufreq_update_util_data, cpu_of(rq))); + if (data) + data->func(data, rq_clock(rq), flags); +} +#else +static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) +{ +#ifdef CONFIG_SMP + rq_load_update(rq); +#endif +} +#endif /* CONFIG_CPU_FREQ */ + +#ifdef CONFIG_NO_HZ_FULL +/* + * Tick may be needed by tasks in the runqueue depending on their policy and + * requirements. If tick is needed, lets send the target an IPI to kick it out + * of nohz mode if necessary. + */ +static inline void sched_update_tick_dependency(struct rq *rq) +{ + int cpu = cpu_of(rq); + + if (!tick_nohz_full_cpu(cpu)) + return; + + if (rq->nr_running < 2) + tick_nohz_dep_clear_cpu(cpu, TICK_DEP_BIT_SCHED); + else + tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED); +} +#else /* !CONFIG_NO_HZ_FULL */ +static inline void sched_update_tick_dependency(struct rq *rq) { } +#endif + +bool sched_task_on_rq(struct task_struct *p) +{ + return task_on_rq_queued(p); +} + +unsigned long get_wchan(struct task_struct *p) +{ + unsigned long ip = 0; + unsigned int state; + + if (!p || p == current) + return 0; + + /* Only get wchan if task is blocked and we can keep it that way. */ + raw_spin_lock_irq(&p->pi_lock); + state = READ_ONCE(p->__state); + smp_rmb(); /* see try_to_wake_up() */ + if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq) + ip = __get_wchan(p); + raw_spin_unlock_irq(&p->pi_lock); + + return ip; +} + +/* + * Add/Remove/Requeue task to/from the runqueue routines + * Context: rq->lock + */ +#define __SCHED_DEQUEUE_TASK(p, rq, flags, func) \ + sched_info_dequeue(rq, p); \ + \ + __list_del_entry(&p->sq_node); \ + if (p->sq_node.prev == p->sq_node.next) { \ + clear_bit(sched_idx2prio(p->sq_node.next - &rq->queue.heads[0], rq), \ + rq->queue.bitmap); \ + func; \ + } + +#define __SCHED_ENQUEUE_TASK(p, rq, flags, func) \ + sched_info_enqueue(rq, p); \ + { \ + int idx, prio; \ + TASK_SCHED_PRIO_IDX(p, rq, idx, prio); \ + list_add_tail(&p->sq_node, &rq->queue.heads[idx]); \ + if (list_is_first(&p->sq_node, &rq->queue.heads[idx])) { \ + set_bit(prio, rq->queue.bitmap); \ + func; \ + } \ + } + +static inline void dequeue_task(struct task_struct *p, struct rq *rq, int flags) +{ +#ifdef ALT_SCHED_DEBUG + lockdep_assert_held(&rq->lock); + + /*printk(KERN_INFO "sched: dequeue(%d) %px %016llx\n", cpu_of(rq), p, p->deadline);*/ + WARN_ONCE(task_rq(p) != rq, "sched: dequeue task reside on cpu%d from cpu%d\n", + task_cpu(p), cpu_of(rq)); +#endif + + __SCHED_DEQUEUE_TASK(p, rq, flags, update_sched_preempt_mask(rq)); + --rq->nr_running; +#ifdef CONFIG_SMP + if (1 == rq->nr_running) + cpumask_clear_cpu(cpu_of(rq), &sched_rq_pending_mask); +#endif + + sched_update_tick_dependency(rq); +} + +static inline void enqueue_task(struct task_struct *p, struct rq *rq, int flags) +{ +#ifdef ALT_SCHED_DEBUG + lockdep_assert_held(&rq->lock); + + /*printk(KERN_INFO "sched: enqueue(%d) %px %d\n", cpu_of(rq), p, p->prio);*/ + WARN_ONCE(task_rq(p) != rq, "sched: enqueue task reside on cpu%d to cpu%d\n", + task_cpu(p), cpu_of(rq)); +#endif + + __SCHED_ENQUEUE_TASK(p, rq, flags, update_sched_preempt_mask(rq)); + ++rq->nr_running; +#ifdef CONFIG_SMP + if (2 == rq->nr_running) + cpumask_set_cpu(cpu_of(rq), &sched_rq_pending_mask); +#endif + + sched_update_tick_dependency(rq); +} + +void requeue_task(struct task_struct *p, struct rq *rq) +{ + struct list_head *node = &p->sq_node; + int deq_idx, idx, prio; + + TASK_SCHED_PRIO_IDX(p, rq, idx, prio); +#ifdef ALT_SCHED_DEBUG + lockdep_assert_held(&rq->lock); + /*printk(KERN_INFO "sched: requeue(%d) %px %016llx\n", cpu_of(rq), p, p->deadline);*/ + WARN_ONCE(task_rq(p) != rq, "sched: cpu[%d] requeue task reside on cpu%d\n", + cpu_of(rq), task_cpu(p)); +#endif + if (list_is_last(node, &rq->queue.heads[idx])) + return; + + __list_del_entry(node); + if (node->prev == node->next && (deq_idx = node->next - &rq->queue.heads[0]) != idx) + clear_bit(sched_idx2prio(deq_idx, rq), rq->queue.bitmap); + + list_add_tail(node, &rq->queue.heads[idx]); + if (list_is_first(node, &rq->queue.heads[idx])) + set_bit(prio, rq->queue.bitmap); + update_sched_preempt_mask(rq); +} + +/* + * try_cmpxchg based fetch_or() macro so it works for different integer types: + */ +#define fetch_or(ptr, mask) \ + ({ \ + typeof(ptr) _ptr = (ptr); \ + typeof(mask) _mask = (mask); \ + typeof(*_ptr) _val = *_ptr; \ + \ + do { \ + } while (!try_cmpxchg(_ptr, &_val, _val | _mask)); \ + _val; \ +}) + +#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) +/* + * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, + * this avoids any races wrt polling state changes and thereby avoids + * spurious IPIs. + */ +static inline bool set_nr_and_not_polling(struct thread_info *ti, int tif) +{ + return !(fetch_or(&ti->flags, 1 << tif) & _TIF_POLLING_NRFLAG); +} + +/* + * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. + * + * If this returns true, then the idle task promises to call + * sched_ttwu_pending() and reschedule soon. + */ +static bool set_nr_if_polling(struct task_struct *p) +{ + struct thread_info *ti = task_thread_info(p); + typeof(ti->flags) val = READ_ONCE(ti->flags); + + do { + if (!(val & _TIF_POLLING_NRFLAG)) + return false; + if (val & _TIF_NEED_RESCHED) + return true; + } while (!try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED)); + + return true; +} + +#else +static inline bool set_nr_and_not_polling(struct thread_info *ti, int tif) +{ + set_ti_thread_flag(ti, tif); + return true; +} + +#ifdef CONFIG_SMP +static inline bool set_nr_if_polling(struct task_struct *p) +{ + return false; +} +#endif +#endif + +static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task) +{ + struct wake_q_node *node = &task->wake_q; + + /* + * Atomically grab the task, if ->wake_q is !nil already it means + * it's already queued (either by us or someone else) and will get the + * wakeup due to that. + * + * In order to ensure that a pending wakeup will observe our pending + * state, even in the failed case, an explicit smp_mb() must be used. + */ + smp_mb__before_atomic(); + if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL))) + return false; + + /* + * The head is context local, there can be no concurrency. + */ + *head->lastp = node; + head->lastp = &node->next; + return true; +} + +/** + * wake_q_add() - queue a wakeup for 'later' waking. + * @head: the wake_q_head to add @task to + * @task: the task to queue for 'later' wakeup + * + * Queue a task for later wakeup, most likely by the wake_up_q() call in the + * same context, _HOWEVER_ this is not guaranteed, the wakeup can come + * instantly. + * + * This function must be used as-if it were wake_up_process(); IOW the task + * must be ready to be woken at this location. + */ +void wake_q_add(struct wake_q_head *head, struct task_struct *task) +{ + if (__wake_q_add(head, task)) + get_task_struct(task); +} + +/** + * wake_q_add_safe() - safely queue a wakeup for 'later' waking. + * @head: the wake_q_head to add @task to + * @task: the task to queue for 'later' wakeup + * + * Queue a task for later wakeup, most likely by the wake_up_q() call in the + * same context, _HOWEVER_ this is not guaranteed, the wakeup can come + * instantly. + * + * This function must be used as-if it were wake_up_process(); IOW the task + * must be ready to be woken at this location. + * + * This function is essentially a task-safe equivalent to wake_q_add(). Callers + * that already hold reference to @task can call the 'safe' version and trust + * wake_q to do the right thing depending whether or not the @task is already + * queued for wakeup. + */ +void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task) +{ + if (!__wake_q_add(head, task)) + put_task_struct(task); +} + +void wake_up_q(struct wake_q_head *head) +{ + struct wake_q_node *node = head->first; + + while (node != WAKE_Q_TAIL) { + struct task_struct *task; + + task = container_of(node, struct task_struct, wake_q); + /* task can safely be re-inserted now: */ + node = node->next; + task->wake_q.next = NULL; + + /* + * wake_up_process() executes a full barrier, which pairs with + * the queueing in wake_q_add() so as not to miss wakeups. + */ + wake_up_process(task); + put_task_struct(task); + } +} + +/* + * resched_curr - mark rq's current task 'to be rescheduled now'. + * + * On UP this means the setting of the need_resched flag, on SMP it + * might also involve a cross-CPU call to trigger the scheduler on + * the target CPU. + */ +static inline void __resched_curr(struct rq *rq, int tif) +{ + struct task_struct *curr = rq->curr; + struct thread_info *cti = task_thread_info(curr); + int cpu; + + lockdep_assert_held(&rq->lock); + + /* + * Always immediately preempt the idle task; no point in delaying doing + * actual work. + */ + if (is_idle_task(curr) && tif == TIF_NEED_RESCHED_LAZY) + tif = TIF_NEED_RESCHED; + + if (cti->flags & ((1 << tif) | _TIF_NEED_RESCHED)) + return; + + cpu = cpu_of(rq); + if (cpu == smp_processor_id()) { + set_ti_thread_flag(cti, tif); + if (tif == TIF_NEED_RESCHED) + set_preempt_need_resched(); + return; + } + + if (set_nr_and_not_polling(cti, tif)) { + if (tif == TIF_NEED_RESCHED) + smp_send_reschedule(cpu); + } else { + trace_sched_wake_idle_without_ipi(cpu); + } +} + +static inline void resched_curr(struct rq *rq) +{ + __resched_curr(rq, TIF_NEED_RESCHED); +} + +#ifdef CONFIG_PREEMPT_DYNAMIC +static DEFINE_STATIC_KEY_FALSE(sk_dynamic_preempt_lazy); +static __always_inline bool dynamic_preempt_lazy(void) +{ + return static_branch_unlikely(&sk_dynamic_preempt_lazy); +} +#else +static __always_inline bool dynamic_preempt_lazy(void) +{ + return IS_ENABLED(CONFIG_PREEMPT_LAZY); +} +#endif + +static __always_inline int get_lazy_tif_bit(void) +{ + if (dynamic_preempt_lazy()) + return TIF_NEED_RESCHED_LAZY; + + return TIF_NEED_RESCHED; +} + +static inline void resched_curr_lazy(struct rq *rq) +{ + __resched_curr(rq, get_lazy_tif_bit()); +} + +void resched_cpu(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + + raw_spin_lock_irqsave(&rq->lock, flags); + if (cpu_online(cpu) || cpu == smp_processor_id()) + resched_curr(cpu_rq(cpu)); + raw_spin_unlock_irqrestore(&rq->lock, flags); +} + +#ifdef CONFIG_SMP +#ifdef CONFIG_NO_HZ_COMMON +/* + * This routine will record that the CPU is going idle with tick stopped. + * This info will be used in performing idle load balancing in the future. + */ +void nohz_balance_enter_idle(int cpu) {} + +/* + * In the semi idle case, use the nearest busy CPU for migrating timers + * from an idle CPU. This is good for power-savings. + * + * We don't do similar optimization for completely idle system, as + * selecting an idle CPU will add more delays to the timers than intended + * (as that CPU's timer base may not be up to date wrt jiffies etc). + */ +int get_nohz_timer_target(void) +{ + int i, cpu = smp_processor_id(), default_cpu = -1; + struct cpumask *mask; + const struct cpumask *hk_mask; + + if (housekeeping_cpu(cpu, HK_TYPE_TIMER)) { + if (!idle_cpu(cpu)) + return cpu; + default_cpu = cpu; + } + + hk_mask = housekeeping_cpumask(HK_TYPE_TIMER); + + for (mask = per_cpu(sched_cpu_topo_masks, cpu); + mask < per_cpu(sched_cpu_topo_end_mask, cpu); mask++) + for_each_cpu_and(i, mask, hk_mask) + if (!idle_cpu(i)) + return i; + + if (default_cpu == -1) + default_cpu = housekeeping_any_cpu(HK_TYPE_TIMER); + cpu = default_cpu; + + return cpu; +} + +/* + * When add_timer_on() enqueues a timer into the timer wheel of an + * idle CPU then this timer might expire before the next timer event + * which is scheduled to wake up that CPU. In case of a completely + * idle system the next event might even be infinite time into the + * future. wake_up_idle_cpu() ensures that the CPU is woken up and + * leaves the inner idle loop so the newly added timer is taken into + * account when the CPU goes back to idle and evaluates the timer + * wheel for the next timer event. + */ +static inline void wake_up_idle_cpu(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + if (cpu == smp_processor_id()) + return; + + /* + * Set TIF_NEED_RESCHED and send an IPI if in the non-polling + * part of the idle loop. This forces an exit from the idle loop + * and a round trip to schedule(). Now this could be optimized + * because a simple new idle loop iteration is enough to + * re-evaluate the next tick. Provided some re-ordering of tick + * nohz functions that would need to follow TIF_NR_POLLING + * clearing: + * + * - On most architectures, a simple fetch_or on ti::flags with a + * "0" value would be enough to know if an IPI needs to be sent. + * + * - x86 needs to perform a last need_resched() check between + * monitor and mwait which doesn't take timers into account. + * There a dedicated TIF_TIMER flag would be required to + * fetch_or here and be checked along with TIF_NEED_RESCHED + * before mwait(). + * + * However, remote timer enqueue is not such a frequent event + * and testing of the above solutions didn't appear to report + * much benefits. + */ + if (set_nr_and_not_polling(task_thread_info(rq->idle), TIF_NEED_RESCHED)) + smp_send_reschedule(cpu); + else + trace_sched_wake_idle_without_ipi(cpu); +} + +static inline bool wake_up_full_nohz_cpu(int cpu) +{ + /* + * We just need the target to call irq_exit() and re-evaluate + * the next tick. The nohz full kick at least implies that. + * If needed we can still optimize that later with an + * empty IRQ. + */ + if (cpu_is_offline(cpu)) + return true; /* Don't try to wake offline CPUs. */ + if (tick_nohz_full_cpu(cpu)) { + if (cpu != smp_processor_id() || + tick_nohz_tick_stopped()) + tick_nohz_full_kick_cpu(cpu); + return true; + } + + return false; +} + +void wake_up_nohz_cpu(int cpu) +{ + if (!wake_up_full_nohz_cpu(cpu)) + wake_up_idle_cpu(cpu); +} + +static void nohz_csd_func(void *info) +{ + struct rq *rq = info; + int cpu = cpu_of(rq); + unsigned int flags; + + /* + * Release the rq::nohz_csd. + */ + flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(cpu)); + WARN_ON(!(flags & NOHZ_KICK_MASK)); + + rq->idle_balance = idle_cpu(cpu); + if (rq->idle_balance) { + rq->nohz_idle_balance = flags; + __raise_softirq_irqoff(SCHED_SOFTIRQ); + } +} + +#endif /* CONFIG_NO_HZ_COMMON */ +#endif /* CONFIG_SMP */ + +static inline void wakeup_preempt(struct rq *rq) +{ + if (sched_rq_first_task(rq) != rq->curr) + resched_curr(rq); +} + +static __always_inline +int __task_state_match(struct task_struct *p, unsigned int state) +{ + if (READ_ONCE(p->__state) & state) + return 1; + + if (READ_ONCE(p->saved_state) & state) + return -1; + + return 0; +} + +static __always_inline +int task_state_match(struct task_struct *p, unsigned int state) +{ + /* + * Serialize against current_save_and_set_rtlock_wait_state(), + * current_restore_rtlock_saved_state(), and __refrigerator(). + */ + guard(raw_spinlock_irq)(&p->pi_lock); + + return __task_state_match(p, state); +} + +/* + * wait_task_inactive - wait for a thread to unschedule. + * + * Wait for the thread to block in any of the states set in @match_state. + * If it changes, i.e. @p might have woken up, then return zero. When we + * succeed in waiting for @p to be off its CPU, we return a positive number + * (its total switch count). If a second call a short while later returns the + * same number, the caller can be sure that @p has remained unscheduled the + * whole time. + * + * The caller must ensure that the task *will* unschedule sometime soon, + * else this function might spin for a *long* time. This function can't + * be called with interrupts off, or it may introduce deadlock with + * smp_call_function() if an IPI is sent by the same process we are + * waiting to become inactive. + */ +unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state) +{ + unsigned long flags; + int running, queued, match; + unsigned long ncsw; + struct rq *rq; + raw_spinlock_t *lock; + + for (;;) { + rq = task_rq(p); + + /* + * If the task is actively running on another CPU + * still, just relax and busy-wait without holding + * any locks. + * + * NOTE! Since we don't hold any locks, it's not + * even sure that "rq" stays as the right runqueue! + * But we don't care, since this will return false + * if the runqueue has changed and p is actually now + * running somewhere else! + */ + while (task_on_cpu(p)) { + if (!task_state_match(p, match_state)) + return 0; + cpu_relax(); + } + + /* + * Ok, time to look more closely! We need the rq + * lock now, to be *sure*. If we're wrong, we'll + * just go back and repeat. + */ + task_access_lock_irqsave(p, &lock, &flags); + trace_sched_wait_task(p); + running = task_on_cpu(p); + queued = p->on_rq; + ncsw = 0; + if ((match = __task_state_match(p, match_state))) { + /* + * When matching on p->saved_state, consider this task + * still queued so it will wait. + */ + if (match < 0) + queued = 1; + ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ + } + task_access_unlock_irqrestore(p, lock, &flags); + + /* + * If it changed from the expected state, bail out now. + */ + if (unlikely(!ncsw)) + break; + + /* + * Was it really running after all now that we + * checked with the proper locks actually held? + * + * Oops. Go back and try again.. + */ + if (unlikely(running)) { + cpu_relax(); + continue; + } + + /* + * It's not enough that it's not actively running, + * it must be off the runqueue _entirely_, and not + * preempted! + * + * So if it was still runnable (but just not actively + * running right now), it's preempted, and we should + * yield - it could be a while. + */ + if (unlikely(queued)) { + ktime_t to = NSEC_PER_SEC / HZ; + + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_hrtimeout(&to, HRTIMER_MODE_REL_HARD); + continue; + } + + /* + * Ahh, all good. It wasn't running, and it wasn't + * runnable, which means that it will never become + * running in the future either. We're all done! + */ + break; + } + + return ncsw; +} + +#ifdef CONFIG_SCHED_HRTICK +/* + * Use HR-timers to deliver accurate preemption points. + */ + +static void hrtick_clear(struct rq *rq) +{ + if (hrtimer_active(&rq->hrtick_timer)) + hrtimer_cancel(&rq->hrtick_timer); +} + +/* + * High-resolution timer tick. + * Runs from hardirq context with interrupts disabled. + */ +static enum hrtimer_restart hrtick(struct hrtimer *timer) +{ + struct rq *rq = container_of(timer, struct rq, hrtick_timer); + + WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); + + raw_spin_lock(&rq->lock); + resched_curr(rq); + raw_spin_unlock(&rq->lock); + + return HRTIMER_NORESTART; +} + +/* + * Use hrtick when: + * - enabled by features + * - hrtimer is actually high res + */ +static inline int hrtick_enabled(struct rq *rq) +{ + /** + * Alt schedule FW doesn't support sched_feat yet + if (!sched_feat(HRTICK)) + return 0; + */ + if (!cpu_active(cpu_of(rq))) + return 0; + return hrtimer_is_hres_active(&rq->hrtick_timer); +} + +#ifdef CONFIG_SMP + +static void __hrtick_restart(struct rq *rq) +{ + struct hrtimer *timer = &rq->hrtick_timer; + ktime_t time = rq->hrtick_time; + + hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD); +} + +/* + * called from hardirq (IPI) context + */ +static void __hrtick_start(void *arg) +{ + struct rq *rq = arg; + + raw_spin_lock(&rq->lock); + __hrtick_restart(rq); + raw_spin_unlock(&rq->lock); +} + +/* + * Called to set the hrtick timer state. + * + * called with rq->lock held and IRQs disabled + */ +static inline void hrtick_start(struct rq *rq, u64 delay) +{ + struct hrtimer *timer = &rq->hrtick_timer; + s64 delta; + + /* + * Don't schedule slices shorter than 10000ns, that just + * doesn't make sense and can cause timer DoS. + */ + delta = max_t(s64, delay, 10000LL); + + rq->hrtick_time = ktime_add_ns(timer->base->get_time(), delta); + + if (rq == this_rq()) + __hrtick_restart(rq); + else + smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); +} + +#else +/* + * Called to set the hrtick timer state. + * + * called with rq->lock held and IRQs disabled + */ +static inline void hrtick_start(struct rq *rq, u64 delay) +{ + /* + * Don't schedule slices shorter than 10000ns, that just + * doesn't make sense. Rely on vruntime for fairness. + */ + delay = max_t(u64, delay, 10000LL); + hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), + HRTIMER_MODE_REL_PINNED_HARD); +} +#endif /* CONFIG_SMP */ + +static void hrtick_rq_init(struct rq *rq) +{ +#ifdef CONFIG_SMP + INIT_CSD(&rq->hrtick_csd, __hrtick_start, rq); +#endif + + hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); + rq->hrtick_timer.function = hrtick; +} +#else /* CONFIG_SCHED_HRTICK */ +static inline int hrtick_enabled(struct rq *rq) +{ + return 0; +} + +static inline void hrtick_clear(struct rq *rq) +{ +} + +static inline void hrtick_rq_init(struct rq *rq) +{ +} +#endif /* CONFIG_SCHED_HRTICK */ + +/* + * activate_task - move a task to the runqueue. + * + * Context: rq->lock + */ +static void activate_task(struct task_struct *p, struct rq *rq) +{ + enqueue_task(p, rq, ENQUEUE_WAKEUP); + + WRITE_ONCE(p->on_rq, TASK_ON_RQ_QUEUED); + ASSERT_EXCLUSIVE_WRITER(p->on_rq); + + /* + * If in_iowait is set, the code below may not trigger any cpufreq + * utilization updates, so do it here explicitly with the IOWAIT flag + * passed. + */ + cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT * p->in_iowait); +} + +static void block_task(struct rq *rq, struct task_struct *p) +{ + dequeue_task(p, rq, DEQUEUE_SLEEP); + + if (p->sched_contributes_to_load) + rq->nr_uninterruptible++; + + if (p->in_iowait) { + atomic_inc(&rq->nr_iowait); + delayacct_blkio_start(); + } + + ASSERT_EXCLUSIVE_WRITER(p->on_rq); + + /* + * The moment this write goes through, ttwu() can swoop in and migrate + * this task, rendering our rq->__lock ineffective. + * + * __schedule() try_to_wake_up() + * LOCK rq->__lock LOCK p->pi_lock + * pick_next_task() + * pick_next_task_fair() + * pick_next_entity() + * dequeue_entities() + * __block_task() + * RELEASE p->on_rq = 0 if (p->on_rq && ...) + * break; + * + * ACQUIRE (after ctrl-dep) + * + * cpu = select_task_rq(); + * set_task_cpu(p, cpu); + * ttwu_queue() + * ttwu_do_activate() + * LOCK rq->__lock + * activate_task() + * STORE p->on_rq = 1 + * UNLOCK rq->__lock + * + * Callers must ensure to not reference @p after this -- we no longer + * own it. + */ + smp_store_release(&p->on_rq, 0); +} + +static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) +{ +#ifdef CONFIG_SMP + /* + * After ->cpu is set up to a new value, task_access_lock(p, ...) can be + * successfully executed on another CPU. We must ensure that updates of + * per-task data have been completed by this moment. + */ + smp_wmb(); + + WRITE_ONCE(task_thread_info(p)->cpu, cpu); +#endif +} + +#ifdef CONFIG_SMP + +void set_task_cpu(struct task_struct *p, unsigned int new_cpu) +{ +#ifdef CONFIG_SCHED_DEBUG + unsigned int state = READ_ONCE(p->__state); + + /* + * We should never call set_task_cpu() on a blocked task, + * ttwu() will sort out the placement. + */ + WARN_ON_ONCE(state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq); + +#ifdef CONFIG_LOCKDEP + /* + * The caller should hold either p->pi_lock or rq->lock, when changing + * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. + * + * sched_move_task() holds both and thus holding either pins the cgroup, + * see task_group(). + */ + WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || + lockdep_is_held(&task_rq(p)->lock))); +#endif + /* + * Clearly, migrating tasks to offline CPUs is a fairly daft thing. + */ + WARN_ON_ONCE(!cpu_online(new_cpu)); + + WARN_ON_ONCE(is_migration_disabled(p)); +#endif + trace_sched_migrate_task(p, new_cpu); + + if (task_cpu(p) != new_cpu) + { + rseq_migrate(p); + sched_mm_cid_migrate_from(p); + perf_event_task_migrate(p); + } + + __set_task_cpu(p, new_cpu); +} + +static void +__do_set_cpus_ptr(struct task_struct *p, const struct cpumask *new_mask) +{ + /* + * This here violates the locking rules for affinity, since we're only + * supposed to change these variables while holding both rq->lock and + * p->pi_lock. + * + * HOWEVER, it magically works, because ttwu() is the only code that + * accesses these variables under p->pi_lock and only does so after + * smp_cond_load_acquire(&p->on_cpu, !VAL), and we're in __schedule() + * before finish_task(). + * + * XXX do further audits, this smells like something putrid. + */ + SCHED_WARN_ON(!p->on_cpu); + p->cpus_ptr = new_mask; +} + +void migrate_disable(void) +{ + struct task_struct *p = current; + int cpu; + + if (p->migration_disabled) { +#ifdef CONFIG_DEBUG_PREEMPT + /* + * Warn about overflow half-way through the range. + */ + WARN_ON_ONCE((s16)p->migration_disabled < 0); +#endif + p->migration_disabled++; + return; + } + + guard(preempt)(); + cpu = smp_processor_id(); + if (cpumask_test_cpu(cpu, &p->cpus_mask)) { + cpu_rq(cpu)->nr_pinned++; + p->migration_disabled = 1; + /* + * Violates locking rules! see comment in __do_set_cpus_ptr(). + */ + if (p->cpus_ptr == &p->cpus_mask) + __do_set_cpus_ptr(p, cpumask_of(cpu)); + } +} +EXPORT_SYMBOL_GPL(migrate_disable); + +void migrate_enable(void) +{ + struct task_struct *p = current; + +#ifdef CONFIG_DEBUG_PREEMPT + /* + * Check both overflow from migrate_disable() and superfluous + * migrate_enable(). + */ + if (WARN_ON_ONCE((s16)p->migration_disabled <= 0)) + return; +#endif + + if (p->migration_disabled > 1) { + p->migration_disabled--; + return; + } + + /* + * Ensure stop_task runs either before or after this, and that + * __set_cpus_allowed_ptr(SCA_MIGRATE_ENABLE) doesn't schedule(). + */ + guard(preempt)(); + /* + * Assumption: current should be running on allowed cpu + */ + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &p->cpus_mask)); + if (p->cpus_ptr != &p->cpus_mask) + __do_set_cpus_ptr(p, &p->cpus_mask); + /* + * Mustn't clear migration_disabled() until cpus_ptr points back at the + * regular cpus_mask, otherwise things that race (eg. + * select_fallback_rq) get confused. + */ + barrier(); + p->migration_disabled = 0; + this_rq()->nr_pinned--; +} +EXPORT_SYMBOL_GPL(migrate_enable); + +static void __migrate_force_enable(struct task_struct *p, struct rq *rq) +{ + if (likely(p->cpus_ptr != &p->cpus_mask)) + __do_set_cpus_ptr(p, &p->cpus_mask); + p->migration_disabled = 0; + /* When p is migrate_disabled, rq->lock should be held */ + rq->nr_pinned--; +} + +static inline bool rq_has_pinned_tasks(struct rq *rq) +{ + return rq->nr_pinned; +} + +/* + * Per-CPU kthreads are allowed to run on !active && online CPUs, see + * __set_cpus_allowed_ptr() and select_fallback_rq(). + */ +static inline bool is_cpu_allowed(struct task_struct *p, int cpu) +{ + /* When not in the task's cpumask, no point in looking further. */ + if (!cpumask_test_cpu(cpu, p->cpus_ptr)) + return false; + + /* migrate_disabled() must be allowed to finish. */ + if (is_migration_disabled(p)) + return cpu_online(cpu); + + /* Non kernel threads are not allowed during either online or offline. */ + if (!(p->flags & PF_KTHREAD)) + return cpu_active(cpu) && task_cpu_possible(cpu, p); + + /* KTHREAD_IS_PER_CPU is always allowed. */ + if (kthread_is_per_cpu(p)) + return cpu_online(cpu); + + /* Regular kernel threads don't get to stay during offline. */ + if (cpu_dying(cpu)) + return false; + + /* But are allowed during online. */ + return cpu_online(cpu); +} + +/* + * This is how migration works: + * + * 1) we invoke migration_cpu_stop() on the target CPU using + * stop_one_cpu(). + * 2) stopper starts to run (implicitly forcing the migrated thread + * off the CPU) + * 3) it checks whether the migrated task is still in the wrong runqueue. + * 4) if it's in the wrong runqueue then the migration thread removes + * it and puts it into the right queue. + * 5) stopper completes and stop_one_cpu() returns and the migration + * is done. + */ + +/* + * move_queued_task - move a queued task to new rq. + * + * Returns (locked) new rq. Old rq's lock is released. + */ +struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu) +{ + lockdep_assert_held(&rq->lock); + + WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING); + dequeue_task(p, rq, 0); + set_task_cpu(p, new_cpu); + raw_spin_unlock(&rq->lock); + + rq = cpu_rq(new_cpu); + + raw_spin_lock(&rq->lock); + WARN_ON_ONCE(task_cpu(p) != new_cpu); + + sched_mm_cid_migrate_to(rq, p); + + sched_task_sanity_check(p, rq); + enqueue_task(p, rq, 0); + WRITE_ONCE(p->on_rq, TASK_ON_RQ_QUEUED); + wakeup_preempt(rq); + + return rq; +} + +struct migration_arg { + struct task_struct *task; + int dest_cpu; +}; + +/* + * Move (not current) task off this CPU, onto the destination CPU. We're doing + * this because either it can't run here any more (set_cpus_allowed() + * away from this CPU, or CPU going down), or because we're + * attempting to rebalance this task on exec (sched_exec). + * + * So we race with normal scheduler movements, but that's OK, as long + * as the task is no longer on this CPU. + */ +static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu) +{ + /* Affinity changed (again). */ + if (!is_cpu_allowed(p, dest_cpu)) + return rq; + + return move_queued_task(rq, p, dest_cpu); +} + +/* + * migration_cpu_stop - this will be executed by a high-prio stopper thread + * and performs thread migration by bumping thread off CPU then + * 'pushing' onto another runqueue. + */ +static int migration_cpu_stop(void *data) +{ + struct migration_arg *arg = data; + struct task_struct *p = arg->task; + struct rq *rq = this_rq(); + unsigned long flags; + + /* + * The original target CPU might have gone down and we might + * be on another CPU but it doesn't matter. + */ + local_irq_save(flags); + /* + * We need to explicitly wake pending tasks before running + * __migrate_task() such that we will not miss enforcing cpus_ptr + * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. + */ + flush_smp_call_function_queue(); + + raw_spin_lock(&p->pi_lock); + raw_spin_lock(&rq->lock); + /* + * If task_rq(p) != rq, it cannot be migrated here, because we're + * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because + * we're holding p->pi_lock. + */ + if (task_rq(p) == rq && task_on_rq_queued(p)) { + update_rq_clock(rq); + rq = __migrate_task(rq, p, arg->dest_cpu); + } + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + + return 0; +} + +static inline void +set_cpus_allowed_common(struct task_struct *p, struct affinity_context *ctx) +{ + cpumask_copy(&p->cpus_mask, ctx->new_mask); + p->nr_cpus_allowed = cpumask_weight(ctx->new_mask); + + /* + * Swap in a new user_cpus_ptr if SCA_USER flag set + */ + if (ctx->flags & SCA_USER) + swap(p->user_cpus_ptr, ctx->user_mask); +} + +static void +__do_set_cpus_allowed(struct task_struct *p, struct affinity_context *ctx) +{ + lockdep_assert_held(&p->pi_lock); + set_cpus_allowed_common(p, ctx); + mm_set_cpus_allowed(p->mm, ctx->new_mask); +} + +/* + * Used for kthread_bind() and select_fallback_rq(), in both cases the user + * affinity (if any) should be destroyed too. + */ +void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) +{ + struct affinity_context ac = { + .new_mask = new_mask, + .user_mask = NULL, + .flags = SCA_USER, /* clear the user requested mask */ + }; + union cpumask_rcuhead { + cpumask_t cpumask; + struct rcu_head rcu; + }; + + __do_set_cpus_allowed(p, &ac); + + if (is_migration_disabled(p) && !cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) + __migrate_force_enable(p, task_rq(p)); + + /* + * Because this is called with p->pi_lock held, it is not possible + * to use kfree() here (when PREEMPT_RT=y), therefore punt to using + * kfree_rcu(). + */ + kfree_rcu((union cpumask_rcuhead *)ac.user_mask, rcu); +} + +int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, + int node) +{ + cpumask_t *user_mask; + unsigned long flags; + + /* + * Always clear dst->user_cpus_ptr first as their user_cpus_ptr's + * may differ by now due to racing. + */ + dst->user_cpus_ptr = NULL; + + /* + * This check is racy and losing the race is a valid situation. + * It is not worth the extra overhead of taking the pi_lock on + * every fork/clone. + */ + if (data_race(!src->user_cpus_ptr)) + return 0; + + user_mask = alloc_user_cpus_ptr(node); + if (!user_mask) + return -ENOMEM; + + /* + * Use pi_lock to protect content of user_cpus_ptr + * + * Though unlikely, user_cpus_ptr can be reset to NULL by a concurrent + * do_set_cpus_allowed(). + */ + raw_spin_lock_irqsave(&src->pi_lock, flags); + if (src->user_cpus_ptr) { + swap(dst->user_cpus_ptr, user_mask); + cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr); + } + raw_spin_unlock_irqrestore(&src->pi_lock, flags); + + if (unlikely(user_mask)) + kfree(user_mask); + + return 0; +} + +static inline struct cpumask *clear_user_cpus_ptr(struct task_struct *p) +{ + struct cpumask *user_mask = NULL; + + swap(p->user_cpus_ptr, user_mask); + + return user_mask; +} + +void release_user_cpus_ptr(struct task_struct *p) +{ + kfree(clear_user_cpus_ptr(p)); +} + +#endif + +/** + * task_curr - is this task currently executing on a CPU? + * @p: the task in question. + * + * Return: 1 if the task is currently executing. 0 otherwise. + */ +inline int task_curr(const struct task_struct *p) +{ + return cpu_curr(task_cpu(p)) == p; +} + +#ifdef CONFIG_SMP +/*** + * kick_process - kick a running thread to enter/exit the kernel + * @p: the to-be-kicked thread + * + * Cause a process which is running on another CPU to enter + * kernel-mode, without any delay. (to get signals handled.) + * + * NOTE: this function doesn't have to take the runqueue lock, + * because all it wants to ensure is that the remote task enters + * the kernel. If the IPI races and the task has been migrated + * to another CPU then no harm is done and the purpose has been + * achieved as well. + */ +void kick_process(struct task_struct *p) +{ + guard(preempt)(); + int cpu = task_cpu(p); + + if ((cpu != smp_processor_id()) && task_curr(p)) + smp_send_reschedule(cpu); +} +EXPORT_SYMBOL_GPL(kick_process); + +/* + * ->cpus_ptr is protected by both rq->lock and p->pi_lock + * + * A few notes on cpu_active vs cpu_online: + * + * - cpu_active must be a subset of cpu_online + * + * - on CPU-up we allow per-CPU kthreads on the online && !active CPU, + * see __set_cpus_allowed_ptr(). At this point the newly online + * CPU isn't yet part of the sched domains, and balancing will not + * see it. + * + * - on cpu-down we clear cpu_active() to mask the sched domains and + * avoid the load balancer to place new tasks on the to be removed + * CPU. Existing tasks will remain running there and will be taken + * off. + * + * This means that fallback selection must not select !active CPUs. + * And can assume that any active CPU must be online. Conversely + * select_task_rq() below may allow selection of !active CPUs in order + * to satisfy the above rules. + */ +static int select_fallback_rq(int cpu, struct task_struct *p) +{ + int nid = cpu_to_node(cpu); + const struct cpumask *nodemask = NULL; + enum { cpuset, possible, fail } state = cpuset; + int dest_cpu; + + /* + * If the node that the CPU is on has been offlined, cpu_to_node() + * will return -1. There is no CPU on the node, and we should + * select the CPU on the other node. + */ + if (nid != -1) { + nodemask = cpumask_of_node(nid); + + /* Look for allowed, online CPU in same node. */ + for_each_cpu(dest_cpu, nodemask) { + if (is_cpu_allowed(p, dest_cpu)) + return dest_cpu; + } + } + + for (;;) { + /* Any allowed, online CPU? */ + for_each_cpu(dest_cpu, p->cpus_ptr) { + if (!is_cpu_allowed(p, dest_cpu)) + continue; + goto out; + } + + /* No more Mr. Nice Guy. */ + switch (state) { + case cpuset: + if (cpuset_cpus_allowed_fallback(p)) { + state = possible; + break; + } + fallthrough; + case possible: + /* + * XXX When called from select_task_rq() we only + * hold p->pi_lock and again violate locking order. + * + * More yuck to audit. + */ + do_set_cpus_allowed(p, task_cpu_possible_mask(p)); + state = fail; + break; + + case fail: + BUG(); + break; + } + } + +out: + if (state != cpuset) { + /* + * Don't tell them about moving exiting tasks or + * kernel threads (both mm NULL), since they never + * leave kernel. + */ + if (p->mm && printk_ratelimit()) { + printk_deferred("process %d (%s) no longer affine to cpu%d\n", + task_pid_nr(p), p->comm, cpu); + } + } + + return dest_cpu; +} + +static inline void +sched_preempt_mask_flush(cpumask_t *mask, int prio, int ref) +{ + int cpu; + + cpumask_copy(mask, sched_preempt_mask + ref); + if (prio < ref) { + for_each_clear_bit(cpu, cpumask_bits(mask), nr_cpumask_bits) { + if (prio < cpu_rq(cpu)->prio) + cpumask_set_cpu(cpu, mask); + } + } else { + for_each_cpu_andnot(cpu, mask, sched_idle_mask) { + if (prio >= cpu_rq(cpu)->prio) + cpumask_clear_cpu(cpu, mask); + } + } +} + +static inline int +preempt_mask_check(cpumask_t *preempt_mask, cpumask_t *allow_mask, int prio) +{ + cpumask_t *mask = sched_preempt_mask + prio; + int pr = atomic_read(&sched_prio_record); + + if (pr != prio && SCHED_QUEUE_BITS - 1 != prio) { + sched_preempt_mask_flush(mask, prio, pr); + atomic_set(&sched_prio_record, prio); + } + + return cpumask_and(preempt_mask, allow_mask, mask); +} + +__read_mostly idle_select_func_t idle_select_func ____cacheline_aligned_in_smp = cpumask_and; + +static inline int select_task_rq(struct task_struct *p) +{ + cpumask_t allow_mask, mask; + + if (unlikely(!cpumask_and(&allow_mask, p->cpus_ptr, cpu_active_mask))) + return select_fallback_rq(task_cpu(p), p); + + if (idle_select_func(&mask, &allow_mask, sched_idle_mask) || + preempt_mask_check(&mask, &allow_mask, task_sched_prio(p))) + return best_mask_cpu(task_cpu(p), &mask); + + return best_mask_cpu(task_cpu(p), &allow_mask); +} + +void sched_set_stop_task(int cpu, struct task_struct *stop) +{ + static struct lock_class_key stop_pi_lock; + struct sched_param stop_param = { .sched_priority = STOP_PRIO }; + struct sched_param start_param = { .sched_priority = 0 }; + struct task_struct *old_stop = cpu_rq(cpu)->stop; + + if (stop) { + /* + * Make it appear like a SCHED_FIFO task, its something + * userspace knows about and won't get confused about. + * + * Also, it will make PI more or less work without too + * much confusion -- but then, stop work should not + * rely on PI working anyway. + */ + sched_setscheduler_nocheck(stop, SCHED_FIFO, &stop_param); + + /* + * The PI code calls rt_mutex_setprio() with ->pi_lock held to + * adjust the effective priority of a task. As a result, + * rt_mutex_setprio() can trigger (RT) balancing operations, + * which can then trigger wakeups of the stop thread to push + * around the current task. + * + * The stop task itself will never be part of the PI-chain, it + * never blocks, therefore that ->pi_lock recursion is safe. + * Tell lockdep about this by placing the stop->pi_lock in its + * own class. + */ + lockdep_set_class(&stop->pi_lock, &stop_pi_lock); + } + + cpu_rq(cpu)->stop = stop; + + if (old_stop) { + /* + * Reset it back to a normal scheduling policy so that + * it can die in pieces. + */ + sched_setscheduler_nocheck(old_stop, SCHED_NORMAL, &start_param); + } +} + +static int affine_move_task(struct rq *rq, struct task_struct *p, int dest_cpu, + raw_spinlock_t *lock, unsigned long irq_flags) + __releases(rq->lock) + __releases(p->pi_lock) +{ + /* Can the task run on the task's current CPU? If so, we're done */ + if (!cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) { + if (is_migration_disabled(p)) + __migrate_force_enable(p, rq); + + if (task_on_cpu(p) || READ_ONCE(p->__state) == TASK_WAKING) { + struct migration_arg arg = { p, dest_cpu }; + + /* Need help from migration thread: drop lock and wait. */ + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, irq_flags); + stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); + return 0; + } + if (task_on_rq_queued(p)) { + /* + * OK, since we're going to drop the lock immediately + * afterwards anyway. + */ + update_rq_clock(rq); + rq = move_queued_task(rq, p, dest_cpu); + lock = &rq->lock; + } + } + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, irq_flags); + return 0; +} + +static int __set_cpus_allowed_ptr_locked(struct task_struct *p, + struct affinity_context *ctx, + struct rq *rq, + raw_spinlock_t *lock, + unsigned long irq_flags) +{ + const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p); + const struct cpumask *cpu_valid_mask = cpu_active_mask; + bool kthread = p->flags & PF_KTHREAD; + int dest_cpu; + int ret = 0; + + if (kthread || is_migration_disabled(p)) { + /* + * Kernel threads are allowed on online && !active CPUs, + * however, during cpu-hot-unplug, even these might get pushed + * away if not KTHREAD_IS_PER_CPU. + * + * Specifically, migration_disabled() tasks must not fail the + * cpumask_any_and_distribute() pick below, esp. so on + * SCA_MIGRATE_ENABLE, otherwise we'll not call + * set_cpus_allowed_common() and actually reset p->cpus_ptr. + */ + cpu_valid_mask = cpu_online_mask; + } + + if (!kthread && !cpumask_subset(ctx->new_mask, cpu_allowed_mask)) { + ret = -EINVAL; + goto out; + } + + /* + * Must re-check here, to close a race against __kthread_bind(), + * sched_setaffinity() is not guaranteed to observe the flag. + */ + if ((ctx->flags & SCA_CHECK) && (p->flags & PF_NO_SETAFFINITY)) { + ret = -EINVAL; + goto out; + } + + if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) + goto out; + + dest_cpu = cpumask_any_and(cpu_valid_mask, ctx->new_mask); + if (dest_cpu >= nr_cpu_ids) { + ret = -EINVAL; + goto out; + } + + __do_set_cpus_allowed(p, ctx); + + return affine_move_task(rq, p, dest_cpu, lock, irq_flags); + +out: + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, irq_flags); + + return ret; +} + +/* + * Change a given task's CPU affinity. Migrate the thread to a + * is removed from the allowed bitmask. + * + * NOTE: the caller must have a valid reference to the task, the + * task must not exit() & deallocate itself prematurely. The + * call is not atomic; no spinlocks may be held. + */ +int __set_cpus_allowed_ptr(struct task_struct *p, + struct affinity_context *ctx) +{ + unsigned long irq_flags; + struct rq *rq; + raw_spinlock_t *lock; + + raw_spin_lock_irqsave(&p->pi_lock, irq_flags); + rq = __task_access_lock(p, &lock); + /* + * Masking should be skipped if SCA_USER or any of the SCA_MIGRATE_* + * flags are set. + */ + if (p->user_cpus_ptr && + !(ctx->flags & SCA_USER) && + cpumask_and(rq->scratch_mask, ctx->new_mask, p->user_cpus_ptr)) + ctx->new_mask = rq->scratch_mask; + + + return __set_cpus_allowed_ptr_locked(p, ctx, rq, lock, irq_flags); +} + +int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) +{ + struct affinity_context ac = { + .new_mask = new_mask, + .flags = 0, + }; + + return __set_cpus_allowed_ptr(p, &ac); +} +EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); + +/* + * Change a given task's CPU affinity to the intersection of its current + * affinity mask and @subset_mask, writing the resulting mask to @new_mask. + * If user_cpus_ptr is defined, use it as the basis for restricting CPU + * affinity or use cpu_online_mask instead. + * + * If the resulting mask is empty, leave the affinity unchanged and return + * -EINVAL. + */ +static int restrict_cpus_allowed_ptr(struct task_struct *p, + struct cpumask *new_mask, + const struct cpumask *subset_mask) +{ + struct affinity_context ac = { + .new_mask = new_mask, + .flags = 0, + }; + unsigned long irq_flags; + raw_spinlock_t *lock; + struct rq *rq; + int err; + + raw_spin_lock_irqsave(&p->pi_lock, irq_flags); + rq = __task_access_lock(p, &lock); + + if (!cpumask_and(new_mask, task_user_cpus(p), subset_mask)) { + err = -EINVAL; + goto err_unlock; + } + + return __set_cpus_allowed_ptr_locked(p, &ac, rq, lock, irq_flags); + +err_unlock: + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, irq_flags); + return err; +} + +/* + * Restrict the CPU affinity of task @p so that it is a subset of + * task_cpu_possible_mask() and point @p->user_cpus_ptr to a copy of the + * old affinity mask. If the resulting mask is empty, we warn and walk + * up the cpuset hierarchy until we find a suitable mask. + */ +void force_compatible_cpus_allowed_ptr(struct task_struct *p) +{ + cpumask_var_t new_mask; + const struct cpumask *override_mask = task_cpu_possible_mask(p); + + alloc_cpumask_var(&new_mask, GFP_KERNEL); + + /* + * __migrate_task() can fail silently in the face of concurrent + * offlining of the chosen destination CPU, so take the hotplug + * lock to ensure that the migration succeeds. + */ + cpus_read_lock(); + if (!cpumask_available(new_mask)) + goto out_set_mask; + + if (!restrict_cpus_allowed_ptr(p, new_mask, override_mask)) + goto out_free_mask; + + /* + * We failed to find a valid subset of the affinity mask for the + * task, so override it based on its cpuset hierarchy. + */ + cpuset_cpus_allowed(p, new_mask); + override_mask = new_mask; + +out_set_mask: + if (printk_ratelimit()) { + printk_deferred("Overriding affinity for process %d (%s) to CPUs %*pbl\n", + task_pid_nr(p), p->comm, + cpumask_pr_args(override_mask)); + } + + WARN_ON(set_cpus_allowed_ptr(p, override_mask)); +out_free_mask: + cpus_read_unlock(); + free_cpumask_var(new_mask); +} + +/* + * Restore the affinity of a task @p which was previously restricted by a + * call to force_compatible_cpus_allowed_ptr(). + * + * It is the caller's responsibility to serialise this with any calls to + * force_compatible_cpus_allowed_ptr(@p). + */ +void relax_compatible_cpus_allowed_ptr(struct task_struct *p) +{ + struct affinity_context ac = { + .new_mask = task_user_cpus(p), + .flags = 0, + }; + int ret; + + /* + * Try to restore the old affinity mask with __sched_setaffinity(). + * Cpuset masking will be done there too. + */ + ret = __sched_setaffinity(p, &ac); + WARN_ON_ONCE(ret); +} + +#else /* CONFIG_SMP */ + +static inline int select_task_rq(struct task_struct *p) +{ + return 0; +} + +static inline bool rq_has_pinned_tasks(struct rq *rq) +{ + return false; +} + +#endif /* !CONFIG_SMP */ + +static void +ttwu_stat(struct task_struct *p, int cpu, int wake_flags) +{ + struct rq *rq; + + if (!schedstat_enabled()) + return; + + rq = this_rq(); + +#ifdef CONFIG_SMP + if (cpu == rq->cpu) { + __schedstat_inc(rq->ttwu_local); + __schedstat_inc(p->stats.nr_wakeups_local); + } else { + /** Alt schedule FW ToDo: + * How to do ttwu_wake_remote + */ + } +#endif /* CONFIG_SMP */ + + __schedstat_inc(rq->ttwu_count); + __schedstat_inc(p->stats.nr_wakeups); +} + +/* + * Mark the task runnable. + */ +static inline void ttwu_do_wakeup(struct task_struct *p) +{ + WRITE_ONCE(p->__state, TASK_RUNNING); + trace_sched_wakeup(p); +} + +static inline void +ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) +{ + if (p->sched_contributes_to_load) + rq->nr_uninterruptible--; + + if ( +#ifdef CONFIG_SMP + !(wake_flags & WF_MIGRATED) && +#endif + p->in_iowait) { + delayacct_blkio_end(p); + atomic_dec(&task_rq(p)->nr_iowait); + } + + activate_task(p, rq); + wakeup_preempt(rq); + + ttwu_do_wakeup(p); +} + +/* + * Consider @p being inside a wait loop: + * + * for (;;) { + * set_current_state(TASK_UNINTERRUPTIBLE); + * + * if (CONDITION) + * break; + * + * schedule(); + * } + * __set_current_state(TASK_RUNNING); + * + * between set_current_state() and schedule(). In this case @p is still + * runnable, so all that needs doing is change p->state back to TASK_RUNNING in + * an atomic manner. + * + * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq + * then schedule() must still happen and p->state can be changed to + * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we + * need to do a full wakeup with enqueue. + * + * Returns: %true when the wakeup is done, + * %false otherwise. + */ +static int ttwu_runnable(struct task_struct *p, int wake_flags) +{ + struct rq *rq; + raw_spinlock_t *lock; + int ret = 0; + + rq = __task_access_lock(p, &lock); + if (task_on_rq_queued(p)) { + if (!task_on_cpu(p)) { + /* + * When on_rq && !on_cpu the task is preempted, see if + * it should preempt the task that is current now. + */ + update_rq_clock(rq); + wakeup_preempt(rq); + } + ttwu_do_wakeup(p); + ret = 1; + } + __task_access_unlock(p, lock); + + return ret; +} + +#ifdef CONFIG_SMP +void sched_ttwu_pending(void *arg) +{ + struct llist_node *llist = arg; + struct rq *rq = this_rq(); + struct task_struct *p, *t; + struct rq_flags rf; + + if (!llist) + return; + + rq_lock_irqsave(rq, &rf); + update_rq_clock(rq); + + llist_for_each_entry_safe(p, t, llist, wake_entry.llist) { + if (WARN_ON_ONCE(p->on_cpu)) + smp_cond_load_acquire(&p->on_cpu, !VAL); + + if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq))) + set_task_cpu(p, cpu_of(rq)); + + ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0); + } + + /* + * Must be after enqueueing at least once task such that + * idle_cpu() does not observe a false-negative -- if it does, + * it is possible for select_idle_siblings() to stack a number + * of tasks on this CPU during that window. + * + * It is OK to clear ttwu_pending when another task pending. + * We will receive IPI after local IRQ enabled and then enqueue it. + * Since now nr_running > 0, idle_cpu() will always get correct result. + */ + WRITE_ONCE(rq->ttwu_pending, 0); + rq_unlock_irqrestore(rq, &rf); +} + +/* + * Prepare the scene for sending an IPI for a remote smp_call + * + * Returns true if the caller can proceed with sending the IPI. + * Returns false otherwise. + */ +bool call_function_single_prep_ipi(int cpu) +{ + if (set_nr_if_polling(cpu_rq(cpu)->idle)) { + trace_sched_wake_idle_without_ipi(cpu); + return false; + } + + return true; +} + +/* + * Queue a task on the target CPUs wake_list and wake the CPU via IPI if + * necessary. The wakee CPU on receipt of the IPI will queue the task + * via sched_ttwu_wakeup() for activation so the wakee incurs the cost + * of the wakeup instead of the waker. + */ +static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) +{ + struct rq *rq = cpu_rq(cpu); + + p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); + + WRITE_ONCE(rq->ttwu_pending, 1); + __smp_call_single_queue(cpu, &p->wake_entry.llist); +} + +static inline bool ttwu_queue_cond(struct task_struct *p, int cpu) +{ + /* + * Do not complicate things with the async wake_list while the CPU is + * in hotplug state. + */ + if (!cpu_active(cpu)) + return false; + + /* Ensure the task will still be allowed to run on the CPU. */ + if (!cpumask_test_cpu(cpu, p->cpus_ptr)) + return false; + + /* + * If the CPU does not share cache, then queue the task on the + * remote rqs wakelist to avoid accessing remote data. + */ + if (!cpus_share_cache(smp_processor_id(), cpu)) + return true; + + if (cpu == smp_processor_id()) + return false; + + /* + * If the wakee cpu is idle, or the task is descheduling and the + * only running task on the CPU, then use the wakelist to offload + * the task activation to the idle (or soon-to-be-idle) CPU as + * the current CPU is likely busy. nr_running is checked to + * avoid unnecessary task stacking. + * + * Note that we can only get here with (wakee) p->on_rq=0, + * p->on_cpu can be whatever, we've done the dequeue, so + * the wakee has been accounted out of ->nr_running. + */ + if (!cpu_rq(cpu)->nr_running) + return true; + + return false; +} + +static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) +{ + if (__is_defined(ALT_SCHED_TTWU_QUEUE) && ttwu_queue_cond(p, cpu)) { + sched_clock_cpu(cpu); /* Sync clocks across CPUs */ + __ttwu_queue_wakelist(p, cpu, wake_flags); + return true; + } + + return false; +} + +void wake_up_if_idle(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + guard(rcu)(); + if (is_idle_task(rcu_dereference(rq->curr))) { + guard(raw_spinlock_irqsave)(&rq->lock); + if (is_idle_task(rq->curr)) + resched_curr(rq); + } +} + +extern struct static_key_false sched_asym_cpucapacity; + +static __always_inline bool sched_asym_cpucap_active(void) +{ + return static_branch_unlikely(&sched_asym_cpucapacity); +} + +bool cpus_equal_capacity(int this_cpu, int that_cpu) +{ + if (!sched_asym_cpucap_active()) + return true; + + if (this_cpu == that_cpu) + return true; + + return arch_scale_cpu_capacity(this_cpu) == arch_scale_cpu_capacity(that_cpu); +} + +bool cpus_share_cache(int this_cpu, int that_cpu) +{ + if (this_cpu == that_cpu) + return true; + + return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); +} +#else /* !CONFIG_SMP */ + +static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) +{ + return false; +} + +#endif /* CONFIG_SMP */ + +static inline void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) +{ + struct rq *rq = cpu_rq(cpu); + + if (ttwu_queue_wakelist(p, cpu, wake_flags)) + return; + + raw_spin_lock(&rq->lock); + update_rq_clock(rq); + ttwu_do_activate(rq, p, wake_flags); + raw_spin_unlock(&rq->lock); +} + +/* + * Invoked from try_to_wake_up() to check whether the task can be woken up. + * + * The caller holds p::pi_lock if p != current or has preemption + * disabled when p == current. + * + * The rules of saved_state: + * + * The related locking code always holds p::pi_lock when updating + * p::saved_state, which means the code is fully serialized in both cases. + * + * For PREEMPT_RT, the lock wait and lock wakeups happen via TASK_RTLOCK_WAIT. + * No other bits set. This allows to distinguish all wakeup scenarios. + * + * For FREEZER, the wakeup happens via TASK_FROZEN. No other bits set. This + * allows us to prevent early wakeup of tasks before they can be run on + * asymmetric ISA architectures (eg ARMv9). + */ +static __always_inline +bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success) +{ + int match; + + if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)) { + WARN_ON_ONCE((state & TASK_RTLOCK_WAIT) && + state != TASK_RTLOCK_WAIT); + } + + *success = !!(match = __task_state_match(p, state)); + + /* + * Saved state preserves the task state across blocking on + * an RT lock or TASK_FREEZABLE tasks. If the state matches, + * set p::saved_state to TASK_RUNNING, but do not wake the task + * because it waits for a lock wakeup or __thaw_task(). Also + * indicate success because from the regular waker's point of + * view this has succeeded. + * + * After acquiring the lock the task will restore p::__state + * from p::saved_state which ensures that the regular + * wakeup is not lost. The restore will also set + * p::saved_state to TASK_RUNNING so any further tests will + * not result in false positives vs. @success + */ + if (match < 0) + p->saved_state = TASK_RUNNING; + + return match > 0; +} + +/* + * Notes on Program-Order guarantees on SMP systems. + * + * MIGRATION + * + * The basic program-order guarantee on SMP systems is that when a task [t] + * migrates, all its activity on its old CPU [c0] happens-before any subsequent + * execution on its new CPU [c1]. + * + * For migration (of runnable tasks) this is provided by the following means: + * + * A) UNLOCK of the rq(c0)->lock scheduling out task t + * B) migration for t is required to synchronize *both* rq(c0)->lock and + * rq(c1)->lock (if not at the same time, then in that order). + * C) LOCK of the rq(c1)->lock scheduling in task + * + * Transitivity guarantees that B happens after A and C after B. + * Note: we only require RCpc transitivity. + * Note: the CPU doing B need not be c0 or c1 + * + * Example: + * + * CPU0 CPU1 CPU2 + * + * LOCK rq(0)->lock + * sched-out X + * sched-in Y + * UNLOCK rq(0)->lock + * + * LOCK rq(0)->lock // orders against CPU0 + * dequeue X + * UNLOCK rq(0)->lock + * + * LOCK rq(1)->lock + * enqueue X + * UNLOCK rq(1)->lock + * + * LOCK rq(1)->lock // orders against CPU2 + * sched-out Z + * sched-in X + * UNLOCK rq(1)->lock + * + * + * BLOCKING -- aka. SLEEP + WAKEUP + * + * For blocking we (obviously) need to provide the same guarantee as for + * migration. However the means are completely different as there is no lock + * chain to provide order. Instead we do: + * + * 1) smp_store_release(X->on_cpu, 0) -- finish_task() + * 2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up() + * + * Example: + * + * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) + * + * LOCK rq(0)->lock LOCK X->pi_lock + * dequeue X + * sched-out X + * smp_store_release(X->on_cpu, 0); + * + * smp_cond_load_acquire(&X->on_cpu, !VAL); + * X->state = WAKING + * set_task_cpu(X,2) + * + * LOCK rq(2)->lock + * enqueue X + * X->state = RUNNING + * UNLOCK rq(2)->lock + * + * LOCK rq(2)->lock // orders against CPU1 + * sched-out Z + * sched-in X + * UNLOCK rq(2)->lock + * + * UNLOCK X->pi_lock + * UNLOCK rq(0)->lock + * + * + * However; for wakeups there is a second guarantee we must provide, namely we + * must observe the state that lead to our wakeup. That is, not only must our + * task observe its own prior state, it must also observe the stores prior to + * its wakeup. + * + * This means that any means of doing remote wakeups must order the CPU doing + * the wakeup against the CPU the task is going to end up running on. This, + * however, is already required for the regular Program-Order guarantee above, + * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). + * + */ + +/** + * try_to_wake_up - wake up a thread + * @p: the thread to be awakened + * @state: the mask of task states that can be woken + * @wake_flags: wake modifier flags (WF_*) + * + * Conceptually does: + * + * If (@state & @p->state) @p->state = TASK_RUNNING. + * + * If the task was not queued/runnable, also place it back on a runqueue. + * + * This function is atomic against schedule() which would dequeue the task. + * + * It issues a full memory barrier before accessing @p->state, see the comment + * with set_current_state(). + * + * Uses p->pi_lock to serialize against concurrent wake-ups. + * + * Relies on p->pi_lock stabilizing: + * - p->sched_class + * - p->cpus_ptr + * - p->sched_task_group + * in order to do migration, see its use of select_task_rq()/set_task_cpu(). + * + * Tries really hard to only take one task_rq(p)->lock for performance. + * Takes rq->lock in: + * - ttwu_runnable() -- old rq, unavoidable, see comment there; + * - ttwu_queue() -- new rq, for enqueue of the task; + * - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us. + * + * As a consequence we race really badly with just about everything. See the + * many memory barriers and their comments for details. + * + * Return: %true if @p->state changes (an actual wakeup was done), + * %false otherwise. + */ +int try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) +{ + guard(preempt)(); + int cpu, success = 0; + + if (p == current) { + /* + * We're waking current, this means 'p->on_rq' and 'task_cpu(p) + * == smp_processor_id()'. Together this means we can special + * case the whole 'p->on_rq && ttwu_runnable()' case below + * without taking any locks. + * + * In particular: + * - we rely on Program-Order guarantees for all the ordering, + * - we're serialized against set_special_state() by virtue of + * it disabling IRQs (this allows not taking ->pi_lock). + */ + if (!ttwu_state_match(p, state, &success)) + goto out; + + trace_sched_waking(p); + ttwu_do_wakeup(p); + goto out; + } + + /* + * If we are going to wake up a thread waiting for CONDITION we + * need to ensure that CONDITION=1 done by the caller can not be + * reordered with p->state check below. This pairs with smp_store_mb() + * in set_current_state() that the waiting thread does. + */ + scoped_guard (raw_spinlock_irqsave, &p->pi_lock) { + smp_mb__after_spinlock(); + if (!ttwu_state_match(p, state, &success)) + break; + + trace_sched_waking(p); + + /* + * Ensure we load p->on_rq _after_ p->state, otherwise it would + * be possible to, falsely, observe p->on_rq == 0 and get stuck + * in smp_cond_load_acquire() below. + * + * sched_ttwu_pending() try_to_wake_up() + * STORE p->on_rq = 1 LOAD p->state + * UNLOCK rq->lock + * + * __schedule() (switch to task 'p') + * LOCK rq->lock smp_rmb(); + * smp_mb__after_spinlock(); + * UNLOCK rq->lock + * + * [task p] + * STORE p->state = UNINTERRUPTIBLE LOAD p->on_rq + * + * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in + * __schedule(). See the comment for smp_mb__after_spinlock(). + * + * A similar smp_rmb() lives in __task_needs_rq_lock(). + */ + smp_rmb(); + if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags)) + break; + +#ifdef CONFIG_SMP + /* + * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be + * possible to, falsely, observe p->on_cpu == 0. + * + * One must be running (->on_cpu == 1) in order to remove oneself + * from the runqueue. + * + * __schedule() (switch to task 'p') try_to_wake_up() + * STORE p->on_cpu = 1 LOAD p->on_rq + * UNLOCK rq->lock + * + * __schedule() (put 'p' to sleep) + * LOCK rq->lock smp_rmb(); + * smp_mb__after_spinlock(); + * STORE p->on_rq = 0 LOAD p->on_cpu + * + * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in + * __schedule(). See the comment for smp_mb__after_spinlock(). + * + * Form a control-dep-acquire with p->on_rq == 0 above, to ensure + * schedule()'s deactivate_task() has 'happened' and p will no longer + * care about it's own p->state. See the comment in __schedule(). + */ + smp_acquire__after_ctrl_dep(); + + /* + * We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq + * == 0), which means we need to do an enqueue, change p->state to + * TASK_WAKING such that we can unlock p->pi_lock before doing the + * enqueue, such as ttwu_queue_wakelist(). + */ + WRITE_ONCE(p->__state, TASK_WAKING); + + /* + * If the owning (remote) CPU is still in the middle of schedule() with + * this task as prev, considering queueing p on the remote CPUs wake_list + * which potentially sends an IPI instead of spinning on p->on_cpu to + * let the waker make forward progress. This is safe because IRQs are + * disabled and the IPI will deliver after on_cpu is cleared. + * + * Ensure we load task_cpu(p) after p->on_cpu: + * + * set_task_cpu(p, cpu); + * STORE p->cpu = @cpu + * __schedule() (switch to task 'p') + * LOCK rq->lock + * smp_mb__after_spin_lock() smp_cond_load_acquire(&p->on_cpu) + * STORE p->on_cpu = 1 LOAD p->cpu + * + * to ensure we observe the correct CPU on which the task is currently + * scheduling. + */ + if (smp_load_acquire(&p->on_cpu) && + ttwu_queue_wakelist(p, task_cpu(p), wake_flags)) + break; + + /* + * If the owning (remote) CPU is still in the middle of schedule() with + * this task as prev, wait until it's done referencing the task. + * + * Pairs with the smp_store_release() in finish_task(). + * + * This ensures that tasks getting woken will be fully ordered against + * their previous state and preserve Program Order. + */ + smp_cond_load_acquire(&p->on_cpu, !VAL); + + sched_task_ttwu(p); + + if ((wake_flags & WF_CURRENT_CPU) && + cpumask_test_cpu(smp_processor_id(), p->cpus_ptr)) + cpu = smp_processor_id(); + else + cpu = select_task_rq(p); + + if (cpu != task_cpu(p)) { + if (p->in_iowait) { + delayacct_blkio_end(p); + atomic_dec(&task_rq(p)->nr_iowait); + } + + wake_flags |= WF_MIGRATED; + set_task_cpu(p, cpu); + } +#else + sched_task_ttwu(p); + + cpu = task_cpu(p); +#endif /* CONFIG_SMP */ + + ttwu_queue(p, cpu, wake_flags); + } +out: + if (success) + ttwu_stat(p, task_cpu(p), wake_flags); + + return success; +} + +static bool __task_needs_rq_lock(struct task_struct *p) +{ + unsigned int state = READ_ONCE(p->__state); + + /* + * Since pi->lock blocks try_to_wake_up(), we don't need rq->lock when + * the task is blocked. Make sure to check @state since ttwu() can drop + * locks at the end, see ttwu_queue_wakelist(). + */ + if (state == TASK_RUNNING || state == TASK_WAKING) + return true; + + /* + * Ensure we load p->on_rq after p->__state, otherwise it would be + * possible to, falsely, observe p->on_rq == 0. + * + * See try_to_wake_up() for a longer comment. + */ + smp_rmb(); + if (p->on_rq) + return true; + +#ifdef CONFIG_SMP + /* + * Ensure the task has finished __schedule() and will not be referenced + * anymore. Again, see try_to_wake_up() for a longer comment. + */ + smp_rmb(); + smp_cond_load_acquire(&p->on_cpu, !VAL); +#endif + + return false; +} + +/** + * task_call_func - Invoke a function on task in fixed state + * @p: Process for which the function is to be invoked, can be @current. + * @func: Function to invoke. + * @arg: Argument to function. + * + * Fix the task in it's current state by avoiding wakeups and or rq operations + * and call @func(@arg) on it. This function can use task_is_runnable() and + * task_curr() to work out what the state is, if required. Given that @func + * can be invoked with a runqueue lock held, it had better be quite + * lightweight. + * + * Returns: + * Whatever @func returns + */ +int task_call_func(struct task_struct *p, task_call_f func, void *arg) +{ + struct rq *rq = NULL; + struct rq_flags rf; + int ret; + + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); + + if (__task_needs_rq_lock(p)) + rq = __task_rq_lock(p, &rf); + + /* + * At this point the task is pinned; either: + * - blocked and we're holding off wakeups (pi->lock) + * - woken, and we're holding off enqueue (rq->lock) + * - queued, and we're holding off schedule (rq->lock) + * - running, and we're holding off de-schedule (rq->lock) + * + * The called function (@func) can use: task_curr(), p->on_rq and + * p->__state to differentiate between these states. + */ + ret = func(p, arg); + + if (rq) + __task_rq_unlock(rq, &rf); + + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); + return ret; +} + +/** + * cpu_curr_snapshot - Return a snapshot of the currently running task + * @cpu: The CPU on which to snapshot the task. + * + * Returns the task_struct pointer of the task "currently" running on + * the specified CPU. If the same task is running on that CPU throughout, + * the return value will be a pointer to that task's task_struct structure. + * If the CPU did any context switches even vaguely concurrently with the + * execution of this function, the return value will be a pointer to the + * task_struct structure of a randomly chosen task that was running on + * that CPU somewhere around the time that this function was executing. + * + * If the specified CPU was offline, the return value is whatever it + * is, perhaps a pointer to the task_struct structure of that CPU's idle + * task, but there is no guarantee. Callers wishing a useful return + * value must take some action to ensure that the specified CPU remains + * online throughout. + * + * This function executes full memory barriers before and after fetching + * the pointer, which permits the caller to confine this function's fetch + * with respect to the caller's accesses to other shared variables. + */ +struct task_struct *cpu_curr_snapshot(int cpu) +{ + struct task_struct *t; + + smp_mb(); /* Pairing determined by caller's synchronization design. */ + t = rcu_dereference(cpu_curr(cpu)); + smp_mb(); /* Pairing determined by caller's synchronization design. */ + return t; +} + +/** + * wake_up_process - Wake up a specific process + * @p: The process to be woken up. + * + * Attempt to wake up the nominated process and move it to the set of runnable + * processes. + * + * Return: 1 if the process was woken up, 0 if it was already running. + * + * This function executes a full memory barrier before accessing the task state. + */ +int wake_up_process(struct task_struct *p) +{ + return try_to_wake_up(p, TASK_NORMAL, 0); +} +EXPORT_SYMBOL(wake_up_process); + +int wake_up_state(struct task_struct *p, unsigned int state) +{ + return try_to_wake_up(p, state, 0); +} + +/* + * Perform scheduler related setup for a newly forked process p. + * p is forked by current. + * + * __sched_fork() is basic setup which is also used by sched_init() to + * initialize the boot CPU's idle task. + */ +static inline void __sched_fork(unsigned long clone_flags, struct task_struct *p) +{ + p->on_rq = 0; + p->on_cpu = 0; + p->utime = 0; + p->stime = 0; + p->sched_time = 0; + +#ifdef CONFIG_SCHEDSTATS + /* Even if schedstat is disabled, there should not be garbage */ + memset(&p->stats, 0, sizeof(p->stats)); +#endif + +#ifdef CONFIG_PREEMPT_NOTIFIERS + INIT_HLIST_HEAD(&p->preempt_notifiers); +#endif + +#ifdef CONFIG_COMPACTION + p->capture_control = NULL; +#endif +#ifdef CONFIG_SMP + p->wake_entry.u_flags = CSD_TYPE_TTWU; +#endif + init_sched_mm_cid(p); +} + +/* + * fork()/clone()-time setup: + */ +int sched_fork(unsigned long clone_flags, struct task_struct *p) +{ + __sched_fork(clone_flags, p); + /* + * We mark the process as NEW here. This guarantees that + * nobody will actually run it, and a signal or other external + * event cannot wake it up and insert it on the runqueue either. + */ + p->__state = TASK_NEW; + + /* + * Make sure we do not leak PI boosting priority to the child. + */ + p->prio = current->normal_prio; + + /* + * Revert to default priority/policy on fork if requested. + */ + if (unlikely(p->sched_reset_on_fork)) { + if (task_has_rt_policy(p)) { + p->policy = SCHED_NORMAL; + p->static_prio = NICE_TO_PRIO(0); + p->rt_priority = 0; + } else if (PRIO_TO_NICE(p->static_prio) < 0) + p->static_prio = NICE_TO_PRIO(0); + + p->prio = p->normal_prio = p->static_prio; + + /* + * We don't need the reset flag anymore after the fork. It has + * fulfilled its duty: + */ + p->sched_reset_on_fork = 0; + } + +#ifdef CONFIG_SCHED_INFO + if (unlikely(sched_info_on())) + memset(&p->sched_info, 0, sizeof(p->sched_info)); +#endif + init_task_preempt_count(p); + + return 0; +} + +int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs) +{ + unsigned long flags; + struct rq *rq; + + /* + * Because we're not yet on the pid-hash, p->pi_lock isn't strictly + * required yet, but lockdep gets upset if rules are violated. + */ + raw_spin_lock_irqsave(&p->pi_lock, flags); + /* + * Share the timeslice between parent and child, thus the + * total amount of pending timeslices in the system doesn't change, + * resulting in more scheduling fairness. + */ + rq = this_rq(); + raw_spin_lock(&rq->lock); + + rq->curr->time_slice /= 2; + p->time_slice = rq->curr->time_slice; +#ifdef CONFIG_SCHED_HRTICK + hrtick_start(rq, rq->curr->time_slice); +#endif + + if (p->time_slice < RESCHED_NS) { + p->time_slice = sysctl_sched_base_slice; + resched_curr(rq); + } + sched_task_fork(p, rq); + raw_spin_unlock(&rq->lock); + + rseq_migrate(p); + /* + * We're setting the CPU for the first time, we don't migrate, + * so use __set_task_cpu(). + */ + __set_task_cpu(p, smp_processor_id()); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + + return 0; +} + +void sched_cancel_fork(struct task_struct *p) +{ +} + +void sched_post_fork(struct task_struct *p) +{ +} + +#ifdef CONFIG_SCHEDSTATS + +DEFINE_STATIC_KEY_FALSE(sched_schedstats); + +static void set_schedstats(bool enabled) +{ + if (enabled) + static_branch_enable(&sched_schedstats); + else + static_branch_disable(&sched_schedstats); +} + +void force_schedstat_enabled(void) +{ + if (!schedstat_enabled()) { + pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); + static_branch_enable(&sched_schedstats); + } +} + +static int __init setup_schedstats(char *str) +{ + int ret = 0; + if (!str) + goto out; + + if (!strcmp(str, "enable")) { + set_schedstats(true); + ret = 1; + } else if (!strcmp(str, "disable")) { + set_schedstats(false); + ret = 1; + } +out: + if (!ret) + pr_warn("Unable to parse schedstats=\n"); + + return ret; +} +__setup("schedstats=", setup_schedstats); + +#ifdef CONFIG_PROC_SYSCTL +static int sysctl_schedstats(const struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + struct ctl_table t; + int err; + int state = static_branch_likely(&sched_schedstats); + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + t = *table; + t.data = &state; + err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); + if (err < 0) + return err; + if (write) + set_schedstats(state); + return err; +} + +static struct ctl_table sched_core_sysctls[] = { + { + .procname = "sched_schedstats", + .data = NULL, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sysctl_schedstats, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +}; +static int __init sched_core_sysctl_init(void) +{ + register_sysctl_init("kernel", sched_core_sysctls); + return 0; +} +late_initcall(sched_core_sysctl_init); +#endif /* CONFIG_PROC_SYSCTL */ +#endif /* CONFIG_SCHEDSTATS */ + +/* + * wake_up_new_task - wake up a newly created task for the first time. + * + * This function will do some initial scheduler statistics housekeeping + * that must be done for every newly created context, then puts the task + * on the runqueue and wakes it. + */ +void wake_up_new_task(struct task_struct *p) +{ + unsigned long flags; + struct rq *rq; + + raw_spin_lock_irqsave(&p->pi_lock, flags); + WRITE_ONCE(p->__state, TASK_RUNNING); + rq = cpu_rq(select_task_rq(p)); +#ifdef CONFIG_SMP + rseq_migrate(p); + /* + * Fork balancing, do it here and not earlier because: + * - cpus_ptr can change in the fork path + * - any previously selected CPU might disappear through hotplug + * + * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, + * as we're not fully set-up yet. + */ + __set_task_cpu(p, cpu_of(rq)); +#endif + + raw_spin_lock(&rq->lock); + update_rq_clock(rq); + + activate_task(p, rq); + trace_sched_wakeup_new(p); + wakeup_preempt(rq); + + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); +} + +#ifdef CONFIG_PREEMPT_NOTIFIERS + +static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key); + +void preempt_notifier_inc(void) +{ + static_branch_inc(&preempt_notifier_key); +} +EXPORT_SYMBOL_GPL(preempt_notifier_inc); + +void preempt_notifier_dec(void) +{ + static_branch_dec(&preempt_notifier_key); +} +EXPORT_SYMBOL_GPL(preempt_notifier_dec); + +/** + * preempt_notifier_register - tell me when current is being preempted & rescheduled + * @notifier: notifier struct to register + */ +void preempt_notifier_register(struct preempt_notifier *notifier) +{ + if (!static_branch_unlikely(&preempt_notifier_key)) + WARN(1, "registering preempt_notifier while notifiers disabled\n"); + + hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); +} +EXPORT_SYMBOL_GPL(preempt_notifier_register); + +/** + * preempt_notifier_unregister - no longer interested in preemption notifications + * @notifier: notifier struct to unregister + * + * This is *not* safe to call from within a preemption notifier. + */ +void preempt_notifier_unregister(struct preempt_notifier *notifier) +{ + hlist_del(¬ifier->link); +} +EXPORT_SYMBOL_GPL(preempt_notifier_unregister); + +static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) +{ + struct preempt_notifier *notifier; + + hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) + notifier->ops->sched_in(notifier, raw_smp_processor_id()); +} + +static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) +{ + if (static_branch_unlikely(&preempt_notifier_key)) + __fire_sched_in_preempt_notifiers(curr); +} + +static void +__fire_sched_out_preempt_notifiers(struct task_struct *curr, + struct task_struct *next) +{ + struct preempt_notifier *notifier; + + hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) + notifier->ops->sched_out(notifier, next); +} + +static __always_inline void +fire_sched_out_preempt_notifiers(struct task_struct *curr, + struct task_struct *next) +{ + if (static_branch_unlikely(&preempt_notifier_key)) + __fire_sched_out_preempt_notifiers(curr, next); +} + +#else /* !CONFIG_PREEMPT_NOTIFIERS */ + +static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) +{ +} + +static inline void +fire_sched_out_preempt_notifiers(struct task_struct *curr, + struct task_struct *next) +{ +} + +#endif /* CONFIG_PREEMPT_NOTIFIERS */ + +static inline void prepare_task(struct task_struct *next) +{ + /* + * Claim the task as running, we do this before switching to it + * such that any running task will have this set. + * + * See the smp_load_acquire(&p->on_cpu) case in ttwu() and + * its ordering comment. + */ + WRITE_ONCE(next->on_cpu, 1); +} + +static inline void finish_task(struct task_struct *prev) +{ +#ifdef CONFIG_SMP + /* + * This must be the very last reference to @prev from this CPU. After + * p->on_cpu is cleared, the task can be moved to a different CPU. We + * must ensure this doesn't happen until the switch is completely + * finished. + * + * In particular, the load of prev->state in finish_task_switch() must + * happen before this. + * + * Pairs with the smp_cond_load_acquire() in try_to_wake_up(). + */ + smp_store_release(&prev->on_cpu, 0); +#else + prev->on_cpu = 0; +#endif +} + +#ifdef CONFIG_SMP + +static void do_balance_callbacks(struct rq *rq, struct balance_callback *head) +{ + void (*func)(struct rq *rq); + struct balance_callback *next; + + lockdep_assert_held(&rq->lock); + + while (head) { + func = (void (*)(struct rq *))head->func; + next = head->next; + head->next = NULL; + head = next; + + func(rq); + } +} + +static void balance_push(struct rq *rq); + +/* + * balance_push_callback is a right abuse of the callback interface and plays + * by significantly different rules. + * + * Where the normal balance_callback's purpose is to be ran in the same context + * that queued it (only later, when it's safe to drop rq->lock again), + * balance_push_callback is specifically targeted at __schedule(). + * + * This abuse is tolerated because it places all the unlikely/odd cases behind + * a single test, namely: rq->balance_callback == NULL. + */ +struct balance_callback balance_push_callback = { + .next = NULL, + .func = balance_push, +}; + +static inline struct balance_callback * +__splice_balance_callbacks(struct rq *rq, bool split) +{ + struct balance_callback *head = rq->balance_callback; + + if (likely(!head)) + return NULL; + + lockdep_assert_rq_held(rq); + /* + * Must not take balance_push_callback off the list when + * splice_balance_callbacks() and balance_callbacks() are not + * in the same rq->lock section. + * + * In that case it would be possible for __schedule() to interleave + * and observe the list empty. + */ + if (split && head == &balance_push_callback) + head = NULL; + else + rq->balance_callback = NULL; + + return head; +} + +struct balance_callback *splice_balance_callbacks(struct rq *rq) +{ + return __splice_balance_callbacks(rq, true); +} + +static void __balance_callbacks(struct rq *rq) +{ + do_balance_callbacks(rq, __splice_balance_callbacks(rq, false)); +} + +void balance_callbacks(struct rq *rq, struct balance_callback *head) +{ + unsigned long flags; + + if (unlikely(head)) { + raw_spin_lock_irqsave(&rq->lock, flags); + do_balance_callbacks(rq, head); + raw_spin_unlock_irqrestore(&rq->lock, flags); + } +} + +#else + +static inline void __balance_callbacks(struct rq *rq) +{ +} +#endif + +static inline void +prepare_lock_switch(struct rq *rq, struct task_struct *next) +{ + /* + * Since the runqueue lock will be released by the next + * task (which is an invalid locking op but in the case + * of the scheduler it's an obvious special-case), so we + * do an early lockdep release here: + */ + spin_release(&rq->lock.dep_map, _THIS_IP_); +#ifdef CONFIG_DEBUG_SPINLOCK + /* this is a valid case when another task releases the spinlock */ + rq->lock.owner = next; +#endif +} + +static inline void finish_lock_switch(struct rq *rq) +{ + /* + * If we are tracking spinlock dependencies then we have to + * fix up the runqueue lock - which gets 'carried over' from + * prev into current: + */ + spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); + __balance_callbacks(rq); + raw_spin_unlock_irq(&rq->lock); +} + +/* + * NOP if the arch has not defined these: + */ + +#ifndef prepare_arch_switch +# define prepare_arch_switch(next) do { } while (0) +#endif + +#ifndef finish_arch_post_lock_switch +# define finish_arch_post_lock_switch() do { } while (0) +#endif + +static inline void kmap_local_sched_out(void) +{ +#ifdef CONFIG_KMAP_LOCAL + if (unlikely(current->kmap_ctrl.idx)) + __kmap_local_sched_out(); +#endif +} + +static inline void kmap_local_sched_in(void) +{ +#ifdef CONFIG_KMAP_LOCAL + if (unlikely(current->kmap_ctrl.idx)) + __kmap_local_sched_in(); +#endif +} + +/** + * prepare_task_switch - prepare to switch tasks + * @rq: the runqueue preparing to switch + * @next: the task we are going to switch to. + * + * This is called with the rq lock held and interrupts off. It must + * be paired with a subsequent finish_task_switch after the context + * switch. + * + * prepare_task_switch sets up locking and calls architecture specific + * hooks. + */ +static inline void +prepare_task_switch(struct rq *rq, struct task_struct *prev, + struct task_struct *next) +{ + kcov_prepare_switch(prev); + sched_info_switch(rq, prev, next); + perf_event_task_sched_out(prev, next); + rseq_preempt(prev); + fire_sched_out_preempt_notifiers(prev, next); + kmap_local_sched_out(); + prepare_task(next); + prepare_arch_switch(next); +} + +/** + * finish_task_switch - clean up after a task-switch + * @rq: runqueue associated with task-switch + * @prev: the thread we just switched away from. + * + * finish_task_switch must be called after the context switch, paired + * with a prepare_task_switch call before the context switch. + * finish_task_switch will reconcile locking set up by prepare_task_switch, + * and do any other architecture-specific cleanup actions. + * + * Note that we may have delayed dropping an mm in context_switch(). If + * so, we finish that here outside of the runqueue lock. (Doing it + * with the lock held can cause deadlocks; see schedule() for + * details.) + * + * The context switch have flipped the stack from under us and restored the + * local variables which were saved when this task called schedule() in the + * past. 'prev == current' is still correct but we need to recalculate this_rq + * because prev may have moved to another CPU. + */ +static struct rq *finish_task_switch(struct task_struct *prev) + __releases(rq->lock) +{ + struct rq *rq = this_rq(); + struct mm_struct *mm = rq->prev_mm; + unsigned int prev_state; + + /* + * The previous task will have left us with a preempt_count of 2 + * because it left us after: + * + * schedule() + * preempt_disable(); // 1 + * __schedule() + * raw_spin_lock_irq(&rq->lock) // 2 + * + * Also, see FORK_PREEMPT_COUNT. + */ + if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, + "corrupted preempt_count: %s/%d/0x%x\n", + current->comm, current->pid, preempt_count())) + preempt_count_set(FORK_PREEMPT_COUNT); + + rq->prev_mm = NULL; + + /* + * A task struct has one reference for the use as "current". + * If a task dies, then it sets TASK_DEAD in tsk->state and calls + * schedule one last time. The schedule call will never return, and + * the scheduled task must drop that reference. + * + * We must observe prev->state before clearing prev->on_cpu (in + * finish_task), otherwise a concurrent wakeup can get prev + * running on another CPU and we could rave with its RUNNING -> DEAD + * transition, resulting in a double drop. + */ + prev_state = READ_ONCE(prev->__state); + vtime_task_switch(prev); + perf_event_task_sched_in(prev, current); + finish_task(prev); + tick_nohz_task_switch(); + finish_lock_switch(rq); + finish_arch_post_lock_switch(); + kcov_finish_switch(current); + /* + * kmap_local_sched_out() is invoked with rq::lock held and + * interrupts disabled. There is no requirement for that, but the + * sched out code does not have an interrupt enabled section. + * Restoring the maps on sched in does not require interrupts being + * disabled either. + */ + kmap_local_sched_in(); + + fire_sched_in_preempt_notifiers(current); + /* + * When switching through a kernel thread, the loop in + * membarrier_{private,global}_expedited() may have observed that + * kernel thread and not issued an IPI. It is therefore possible to + * schedule between user->kernel->user threads without passing though + * switch_mm(). Membarrier requires a barrier after storing to + * rq->curr, before returning to userspace, so provide them here: + * + * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly + * provided by mmdrop(), + * - a sync_core for SYNC_CORE. + */ + if (mm) { + membarrier_mm_sync_core_before_usermode(mm); + mmdrop_sched(mm); + } + if (unlikely(prev_state == TASK_DEAD)) { + /* Task is done with its stack. */ + put_task_stack(prev); + + put_task_struct_rcu_user(prev); + } + + return rq; +} + +/** + * schedule_tail - first thing a freshly forked thread must call. + * @prev: the thread we just switched away from. + */ +asmlinkage __visible void schedule_tail(struct task_struct *prev) + __releases(rq->lock) +{ + /* + * New tasks start with FORK_PREEMPT_COUNT, see there and + * finish_task_switch() for details. + * + * finish_task_switch() will drop rq->lock() and lower preempt_count + * and the preempt_enable() will end up enabling preemption (on + * PREEMPT_COUNT kernels). + */ + + finish_task_switch(prev); + preempt_enable(); + + if (current->set_child_tid) + put_user(task_pid_vnr(current), current->set_child_tid); + + calculate_sigpending(); +} + +/* + * context_switch - switch to the new MM and the new thread's register state. + */ +static __always_inline struct rq * +context_switch(struct rq *rq, struct task_struct *prev, + struct task_struct *next) +{ + prepare_task_switch(rq, prev, next); + + /* + * For paravirt, this is coupled with an exit in switch_to to + * combine the page table reload and the switch backend into + * one hypercall. + */ + arch_start_context_switch(prev); + + /* + * kernel -> kernel lazy + transfer active + * user -> kernel lazy + mmgrab() active + * + * kernel -> user switch + mmdrop() active + * user -> user switch + * + * switch_mm_cid() needs to be updated if the barriers provided + * by context_switch() are modified. + */ + if (!next->mm) { // to kernel + enter_lazy_tlb(prev->active_mm, next); + + next->active_mm = prev->active_mm; + if (prev->mm) // from user + mmgrab(prev->active_mm); + else + prev->active_mm = NULL; + } else { // to user + membarrier_switch_mm(rq, prev->active_mm, next->mm); + /* + * sys_membarrier() requires an smp_mb() between setting + * rq->curr / membarrier_switch_mm() and returning to userspace. + * + * The below provides this either through switch_mm(), or in + * case 'prev->active_mm == next->mm' through + * finish_task_switch()'s mmdrop(). + */ + switch_mm_irqs_off(prev->active_mm, next->mm, next); + lru_gen_use_mm(next->mm); + + if (!prev->mm) { // from kernel + /* will mmdrop() in finish_task_switch(). */ + rq->prev_mm = prev->active_mm; + prev->active_mm = NULL; + } + } + + /* switch_mm_cid() requires the memory barriers above. */ + switch_mm_cid(rq, prev, next); + + prepare_lock_switch(rq, next); + + /* Here we just switch the register state and the stack. */ + switch_to(prev, next, prev); + barrier(); + + return finish_task_switch(prev); +} + +/* + * nr_running, nr_uninterruptible and nr_context_switches: + * + * externally visible scheduler statistics: current number of runnable + * threads, total number of context switches performed since bootup. + */ +unsigned int nr_running(void) +{ + unsigned int i, sum = 0; + + for_each_online_cpu(i) + sum += cpu_rq(i)->nr_running; + + return sum; +} + +/* + * Check if only the current task is running on the CPU. + * + * Caution: this function does not check that the caller has disabled + * preemption, thus the result might have a time-of-check-to-time-of-use + * race. The caller is responsible to use it correctly, for example: + * + * - from a non-preemptible section (of course) + * + * - from a thread that is bound to a single CPU + * + * - in a loop with very short iterations (e.g. a polling loop) + */ +bool single_task_running(void) +{ + return raw_rq()->nr_running == 1; +} +EXPORT_SYMBOL(single_task_running); + +unsigned long long nr_context_switches_cpu(int cpu) +{ + return cpu_rq(cpu)->nr_switches; +} + +unsigned long long nr_context_switches(void) +{ + int i; + unsigned long long sum = 0; + + for_each_possible_cpu(i) + sum += cpu_rq(i)->nr_switches; + + return sum; +} + +/* + * Consumers of these two interfaces, like for example the cpuidle menu + * governor, are using nonsensical data. Preferring shallow idle state selection + * for a CPU that has IO-wait which might not even end up running the task when + * it does become runnable. + */ + +unsigned int nr_iowait_cpu(int cpu) +{ + return atomic_read(&cpu_rq(cpu)->nr_iowait); +} + +/* + * IO-wait accounting, and how it's mostly bollocks (on SMP). + * + * The idea behind IO-wait account is to account the idle time that we could + * have spend running if it were not for IO. That is, if we were to improve the + * storage performance, we'd have a proportional reduction in IO-wait time. + * + * This all works nicely on UP, where, when a task blocks on IO, we account + * idle time as IO-wait, because if the storage were faster, it could've been + * running and we'd not be idle. + * + * This has been extended to SMP, by doing the same for each CPU. This however + * is broken. + * + * Imagine for instance the case where two tasks block on one CPU, only the one + * CPU will have IO-wait accounted, while the other has regular idle. Even + * though, if the storage were faster, both could've ran at the same time, + * utilising both CPUs. + * + * This means, that when looking globally, the current IO-wait accounting on + * SMP is a lower bound, by reason of under accounting. + * + * Worse, since the numbers are provided per CPU, they are sometimes + * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly + * associated with any one particular CPU, it can wake to another CPU than it + * blocked on. This means the per CPU IO-wait number is meaningless. + * + * Task CPU affinities can make all that even more 'interesting'. + */ + +unsigned int nr_iowait(void) +{ + unsigned int i, sum = 0; + + for_each_possible_cpu(i) + sum += nr_iowait_cpu(i); + + return sum; +} + +#ifdef CONFIG_SMP + +/* + * sched_exec - execve() is a valuable balancing opportunity, because at + * this point the task has the smallest effective memory and cache + * footprint. + */ +void sched_exec(void) +{ +} + +#endif + +DEFINE_PER_CPU(struct kernel_stat, kstat); +DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); + +EXPORT_PER_CPU_SYMBOL(kstat); +EXPORT_PER_CPU_SYMBOL(kernel_cpustat); + +static inline void update_curr(struct rq *rq, struct task_struct *p) +{ + s64 ns = rq->clock_task - p->last_ran; + + p->sched_time += ns; + cgroup_account_cputime(p, ns); + account_group_exec_runtime(p, ns); + + p->time_slice -= ns; + p->last_ran = rq->clock_task; +} + +/* + * Return accounted runtime for the task. + * Return separately the current's pending runtime that have not been + * accounted yet. + */ +unsigned long long task_sched_runtime(struct task_struct *p) +{ + unsigned long flags; + struct rq *rq; + raw_spinlock_t *lock; + u64 ns; + +#if defined(CONFIG_64BIT) && defined(CONFIG_SMP) + /* + * 64-bit doesn't need locks to atomically read a 64-bit value. + * So we have a optimization chance when the task's delta_exec is 0. + * Reading ->on_cpu is racy, but this is OK. + * + * If we race with it leaving CPU, we'll take a lock. So we're correct. + * If we race with it entering CPU, unaccounted time is 0. This is + * indistinguishable from the read occurring a few cycles earlier. + * If we see ->on_cpu without ->on_rq, the task is leaving, and has + * been accounted, so we're correct here as well. + */ + if (!p->on_cpu || !task_on_rq_queued(p)) + return tsk_seruntime(p); +#endif + + rq = task_access_lock_irqsave(p, &lock, &flags); + /* + * Must be ->curr _and_ ->on_rq. If dequeued, we would + * project cycles that may never be accounted to this + * thread, breaking clock_gettime(). + */ + if (p == rq->curr && task_on_rq_queued(p)) { + update_rq_clock(rq); + update_curr(rq, p); + } + ns = tsk_seruntime(p); + task_access_unlock_irqrestore(p, lock, &flags); + + return ns; +} + +/* This manages tasks that have run out of timeslice during a scheduler_tick */ +static inline void scheduler_task_tick(struct rq *rq) +{ + struct task_struct *p = rq->curr; + + if (is_idle_task(p)) + return; + + update_curr(rq, p); + cpufreq_update_util(rq, 0); + + /* + * Tasks have less than RESCHED_NS of time slice left they will be + * rescheduled. + */ + if (p->time_slice >= RESCHED_NS) + return; + set_tsk_need_resched(p); + set_preempt_need_resched(); +} + +#ifdef CONFIG_SCHED_DEBUG +static u64 cpu_resched_latency(struct rq *rq) +{ + int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms); + u64 resched_latency, now = rq_clock(rq); + static bool warned_once; + + if (sysctl_resched_latency_warn_once && warned_once) + return 0; + + if (!need_resched() || !latency_warn_ms) + return 0; + + if (system_state == SYSTEM_BOOTING) + return 0; + + if (!rq->last_seen_need_resched_ns) { + rq->last_seen_need_resched_ns = now; + rq->ticks_without_resched = 0; + return 0; + } + + rq->ticks_without_resched++; + resched_latency = now - rq->last_seen_need_resched_ns; + if (resched_latency <= latency_warn_ms * NSEC_PER_MSEC) + return 0; + + warned_once = true; + + return resched_latency; +} + +static int __init setup_resched_latency_warn_ms(char *str) +{ + long val; + + if ((kstrtol(str, 0, &val))) { + pr_warn("Unable to set resched_latency_warn_ms\n"); + return 1; + } + + sysctl_resched_latency_warn_ms = val; + return 1; +} +__setup("resched_latency_warn_ms=", setup_resched_latency_warn_ms); +#else +static inline u64 cpu_resched_latency(struct rq *rq) { return 0; } +#endif /* CONFIG_SCHED_DEBUG */ + +/* + * This function gets called by the timer code, with HZ frequency. + * We call it with interrupts disabled. + */ +void sched_tick(void) +{ + int cpu __maybe_unused = smp_processor_id(); + struct rq *rq = cpu_rq(cpu); + struct task_struct *curr = rq->curr; + u64 resched_latency; + + if (housekeeping_cpu(cpu, HK_TYPE_TICK)) + arch_scale_freq_tick(); + + sched_clock_tick(); + + raw_spin_lock(&rq->lock); + update_rq_clock(rq); + + if (dynamic_preempt_lazy() && tif_test_bit(TIF_NEED_RESCHED_LAZY)) + resched_curr(rq); + + scheduler_task_tick(rq); + if (sched_feat(LATENCY_WARN)) + resched_latency = cpu_resched_latency(rq); + calc_global_load_tick(rq); + + task_tick_mm_cid(rq, rq->curr); + + raw_spin_unlock(&rq->lock); + + if (sched_feat(LATENCY_WARN) && resched_latency) + resched_latency_warn(cpu, resched_latency); + + perf_event_task_tick(); + + if (curr->flags & PF_WQ_WORKER) + wq_worker_tick(curr); +} + +#ifdef CONFIG_NO_HZ_FULL + +struct tick_work { + int cpu; + atomic_t state; + struct delayed_work work; +}; +/* Values for ->state, see diagram below. */ +#define TICK_SCHED_REMOTE_OFFLINE 0 +#define TICK_SCHED_REMOTE_OFFLINING 1 +#define TICK_SCHED_REMOTE_RUNNING 2 + +/* + * State diagram for ->state: + * + * + * TICK_SCHED_REMOTE_OFFLINE + * | ^ + * | | + * | | sched_tick_remote() + * | | + * | | + * +--TICK_SCHED_REMOTE_OFFLINING + * | ^ + * | | + * sched_tick_start() | | sched_tick_stop() + * | | + * V | + * TICK_SCHED_REMOTE_RUNNING + * + * + * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote() + * and sched_tick_start() are happy to leave the state in RUNNING. + */ + +static struct tick_work __percpu *tick_work_cpu; + +static void sched_tick_remote(struct work_struct *work) +{ + struct delayed_work *dwork = to_delayed_work(work); + struct tick_work *twork = container_of(dwork, struct tick_work, work); + int cpu = twork->cpu; + struct rq *rq = cpu_rq(cpu); + int os; + + /* + * Handle the tick only if it appears the remote CPU is running in full + * dynticks mode. The check is racy by nature, but missing a tick or + * having one too much is no big deal because the scheduler tick updates + * statistics and checks timeslices in a time-independent way, regardless + * of when exactly it is running. + */ + if (tick_nohz_tick_stopped_cpu(cpu)) { + guard(raw_spinlock_irqsave)(&rq->lock); + struct task_struct *curr = rq->curr; + + if (cpu_online(cpu)) { + update_rq_clock(rq); + + if (!is_idle_task(curr)) { + /* + * Make sure the next tick runs within a + * reasonable amount of time. + */ + u64 delta = rq_clock_task(rq) - curr->last_ran; + WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); + } + scheduler_task_tick(rq); + + calc_load_nohz_remote(rq); + } + } + + /* + * Run the remote tick once per second (1Hz). This arbitrary + * frequency is large enough to avoid overload but short enough + * to keep scheduler internal stats reasonably up to date. But + * first update state to reflect hotplug activity if required. + */ + os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING); + WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE); + if (os == TICK_SCHED_REMOTE_RUNNING) + queue_delayed_work(system_unbound_wq, dwork, HZ); +} + +static void sched_tick_start(int cpu) +{ + int os; + struct tick_work *twork; + + if (housekeeping_cpu(cpu, HK_TYPE_TICK)) + return; + + WARN_ON_ONCE(!tick_work_cpu); + + twork = per_cpu_ptr(tick_work_cpu, cpu); + os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING); + WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING); + if (os == TICK_SCHED_REMOTE_OFFLINE) { + twork->cpu = cpu; + INIT_DELAYED_WORK(&twork->work, sched_tick_remote); + queue_delayed_work(system_unbound_wq, &twork->work, HZ); + } +} + +#ifdef CONFIG_HOTPLUG_CPU +static void sched_tick_stop(int cpu) +{ + struct tick_work *twork; + int os; + + if (housekeeping_cpu(cpu, HK_TYPE_TICK)) + return; + + WARN_ON_ONCE(!tick_work_cpu); + + twork = per_cpu_ptr(tick_work_cpu, cpu); + /* There cannot be competing actions, but don't rely on stop-machine. */ + os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING); + WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING); + /* Don't cancel, as this would mess up the state machine. */ +} +#endif /* CONFIG_HOTPLUG_CPU */ + +int __init sched_tick_offload_init(void) +{ + tick_work_cpu = alloc_percpu(struct tick_work); + BUG_ON(!tick_work_cpu); + return 0; +} + +#else /* !CONFIG_NO_HZ_FULL */ +static inline void sched_tick_start(int cpu) { } +static inline void sched_tick_stop(int cpu) { } +#endif + +#if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \ + defined(CONFIG_PREEMPT_TRACER)) +/* + * If the value passed in is equal to the current preempt count + * then we just disabled preemption. Start timing the latency. + */ +static inline void preempt_latency_start(int val) +{ + if (preempt_count() == val) { + unsigned long ip = get_lock_parent_ip(); +#ifdef CONFIG_DEBUG_PREEMPT + current->preempt_disable_ip = ip; +#endif + trace_preempt_off(CALLER_ADDR0, ip); + } +} + +void preempt_count_add(int val) +{ +#ifdef CONFIG_DEBUG_PREEMPT + /* + * Underflow? + */ + if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) + return; +#endif + __preempt_count_add(val); +#ifdef CONFIG_DEBUG_PREEMPT + /* + * Spinlock count overflowing soon? + */ + DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= + PREEMPT_MASK - 10); +#endif + preempt_latency_start(val); +} +EXPORT_SYMBOL(preempt_count_add); +NOKPROBE_SYMBOL(preempt_count_add); + +/* + * If the value passed in equals to the current preempt count + * then we just enabled preemption. Stop timing the latency. + */ +static inline void preempt_latency_stop(int val) +{ + if (preempt_count() == val) + trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); +} + +void preempt_count_sub(int val) +{ +#ifdef CONFIG_DEBUG_PREEMPT + /* + * Underflow? + */ + if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) + return; + /* + * Is the spinlock portion underflowing? + */ + if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && + !(preempt_count() & PREEMPT_MASK))) + return; +#endif + + preempt_latency_stop(val); + __preempt_count_sub(val); +} +EXPORT_SYMBOL(preempt_count_sub); +NOKPROBE_SYMBOL(preempt_count_sub); + +#else +static inline void preempt_latency_start(int val) { } +static inline void preempt_latency_stop(int val) { } +#endif + +static inline unsigned long get_preempt_disable_ip(struct task_struct *p) +{ +#ifdef CONFIG_DEBUG_PREEMPT + return p->preempt_disable_ip; +#else + return 0; +#endif +} + +/* + * Print scheduling while atomic bug: + */ +static noinline void __schedule_bug(struct task_struct *prev) +{ + /* Save this before calling printk(), since that will clobber it */ + unsigned long preempt_disable_ip = get_preempt_disable_ip(current); + + if (oops_in_progress) + return; + + printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", + prev->comm, prev->pid, preempt_count()); + + debug_show_held_locks(prev); + print_modules(); + if (irqs_disabled()) + print_irqtrace_events(prev); + if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)) { + pr_err("Preemption disabled at:"); + print_ip_sym(KERN_ERR, preempt_disable_ip); + } + check_panic_on_warn("scheduling while atomic"); + + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); +} + +/* + * Various schedule()-time debugging checks and statistics: + */ +static inline void schedule_debug(struct task_struct *prev, bool preempt) +{ +#ifdef CONFIG_SCHED_STACK_END_CHECK + if (task_stack_end_corrupted(prev)) + panic("corrupted stack end detected inside scheduler\n"); + + if (task_scs_end_corrupted(prev)) + panic("corrupted shadow stack detected inside scheduler\n"); +#endif + +#ifdef CONFIG_DEBUG_ATOMIC_SLEEP + if (!preempt && READ_ONCE(prev->__state) && prev->non_block_count) { + printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n", + prev->comm, prev->pid, prev->non_block_count); + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); + } +#endif + + if (unlikely(in_atomic_preempt_off())) { + __schedule_bug(prev); + preempt_count_set(PREEMPT_DISABLED); + } + rcu_sleep_check(); + SCHED_WARN_ON(ct_state() == CT_STATE_USER); + + profile_hit(SCHED_PROFILING, __builtin_return_address(0)); + + schedstat_inc(this_rq()->sched_count); +} + +#ifdef ALT_SCHED_DEBUG +void alt_sched_debug(void) +{ + printk(KERN_INFO "sched: pending: 0x%04lx, idle: 0x%04lx, sg_idle: 0x%04lx," + " ecore_idle: 0x%04lx\n", + sched_rq_pending_mask.bits[0], + sched_idle_mask->bits[0], + sched_pcore_idle_mask->bits[0], + sched_ecore_idle_mask->bits[0]); +} +#endif + +#ifdef CONFIG_SMP + +#ifdef CONFIG_PREEMPT_RT +#define SCHED_NR_MIGRATE_BREAK 8 +#else +#define SCHED_NR_MIGRATE_BREAK 32 +#endif + +const_debug unsigned int sysctl_sched_nr_migrate = SCHED_NR_MIGRATE_BREAK; + +/* + * Migrate pending tasks in @rq to @dest_cpu + */ +static inline int +migrate_pending_tasks(struct rq *rq, struct rq *dest_rq, const int dest_cpu) +{ + struct task_struct *p, *skip = rq->curr; + int nr_migrated = 0; + int nr_tries = min(rq->nr_running / 2, sysctl_sched_nr_migrate); + + /* WA to check rq->curr is still on rq */ + if (!task_on_rq_queued(skip)) + return 0; + + while (skip != rq->idle && nr_tries && + (p = sched_rq_next_task(skip, rq)) != rq->idle) { + skip = sched_rq_next_task(p, rq); + if (cpumask_test_cpu(dest_cpu, p->cpus_ptr)) { + __SCHED_DEQUEUE_TASK(p, rq, 0, ); + set_task_cpu(p, dest_cpu); + sched_task_sanity_check(p, dest_rq); + sched_mm_cid_migrate_to(dest_rq, p); + __SCHED_ENQUEUE_TASK(p, dest_rq, 0, ); + nr_migrated++; + } + nr_tries--; + } + + return nr_migrated; +} + +static inline int take_other_rq_tasks(struct rq *rq, int cpu) +{ + cpumask_t *topo_mask, *end_mask, chk; + + if (unlikely(!rq->online)) + return 0; + + if (cpumask_empty(&sched_rq_pending_mask)) + return 0; + + topo_mask = per_cpu(sched_cpu_topo_masks, cpu); + end_mask = per_cpu(sched_cpu_topo_end_mask, cpu); + do { + int i; + + if (!cpumask_and(&chk, &sched_rq_pending_mask, topo_mask)) + continue; + + for_each_cpu_wrap(i, &chk, cpu) { + int nr_migrated; + struct rq *src_rq; + + src_rq = cpu_rq(i); + if (!do_raw_spin_trylock(&src_rq->lock)) + continue; + spin_acquire(&src_rq->lock.dep_map, + SINGLE_DEPTH_NESTING, 1, _RET_IP_); + + if ((nr_migrated = migrate_pending_tasks(src_rq, rq, cpu))) { + src_rq->nr_running -= nr_migrated; + if (src_rq->nr_running < 2) + cpumask_clear_cpu(i, &sched_rq_pending_mask); + + spin_release(&src_rq->lock.dep_map, _RET_IP_); + do_raw_spin_unlock(&src_rq->lock); + + rq->nr_running += nr_migrated; + if (rq->nr_running > 1) + cpumask_set_cpu(cpu, &sched_rq_pending_mask); + + update_sched_preempt_mask(rq); + cpufreq_update_util(rq, 0); + + return 1; + } + + spin_release(&src_rq->lock.dep_map, _RET_IP_); + do_raw_spin_unlock(&src_rq->lock); + } + } while (++topo_mask < end_mask); + + return 0; +} +#endif + +static inline void time_slice_expired(struct task_struct *p, struct rq *rq) +{ + p->time_slice = sysctl_sched_base_slice; + + sched_task_renew(p, rq); + + if (SCHED_FIFO != p->policy && task_on_rq_queued(p)) + requeue_task(p, rq); +} + +/* + * Timeslices below RESCHED_NS are considered as good as expired as there's no + * point rescheduling when there's so little time left. + */ +static inline void check_curr(struct task_struct *p, struct rq *rq) +{ + if (unlikely(rq->idle == p)) + return; + + update_curr(rq, p); + + if (p->time_slice < RESCHED_NS) + time_slice_expired(p, rq); +} + +static inline struct task_struct * +choose_next_task(struct rq *rq, int cpu) +{ + struct task_struct *next = sched_rq_first_task(rq); + + if (next == rq->idle) { +#ifdef CONFIG_SMP + if (!take_other_rq_tasks(rq, cpu)) { + if (likely(rq->balance_func && rq->online)) + rq->balance_func(rq, cpu); +#endif /* CONFIG_SMP */ + + schedstat_inc(rq->sched_goidle); + /*printk(KERN_INFO "sched: choose_next_task(%d) idle %px\n", cpu, next);*/ + return next; +#ifdef CONFIG_SMP + } + next = sched_rq_first_task(rq); +#endif + } +#ifdef CONFIG_HIGH_RES_TIMERS + hrtick_start(rq, next->time_slice); +#endif + /*printk(KERN_INFO "sched: choose_next_task(%d) next %px\n", cpu, next);*/ + return next; +} + +/* + * Constants for the sched_mode argument of __schedule(). + * + * The mode argument allows RT enabled kernels to differentiate a + * preemption from blocking on an 'sleeping' spin/rwlock. + */ + #define SM_IDLE (-1) + #define SM_NONE 0 + #define SM_PREEMPT 1 + #define SM_RTLOCK_WAIT 2 + +/* + * Helper function for __schedule() + * + * If a task does not have signals pending, deactivate it + * Otherwise marks the task's __state as RUNNING + */ +static bool try_to_block_task(struct rq *rq, struct task_struct *p, + unsigned long task_state) +{ + if (signal_pending_state(task_state, p)) { + WRITE_ONCE(p->__state, TASK_RUNNING); + return false; + } + p->sched_contributes_to_load = + (task_state & TASK_UNINTERRUPTIBLE) && + !(task_state & TASK_NOLOAD) && + !(task_state & TASK_FROZEN); + + /* + * __schedule() ttwu() + * prev_state = prev->state; if (p->on_rq && ...) + * if (prev_state) goto out; + * p->on_rq = 0; smp_acquire__after_ctrl_dep(); + * p->state = TASK_WAKING + * + * Where __schedule() and ttwu() have matching control dependencies. + * + * After this, schedule() must not care about p->state any more. + */ + sched_task_deactivate(p, rq); + block_task(rq, p); + return true; +} + +/* + * schedule() is the main scheduler function. + * + * The main means of driving the scheduler and thus entering this function are: + * + * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. + * + * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return + * paths. For example, see arch/x86/entry_64.S. + * + * To drive preemption between tasks, the scheduler sets the flag in timer + * interrupt handler sched_tick(). + * + * 3. Wakeups don't really cause entry into schedule(). They add a + * task to the run-queue and that's it. + * + * Now, if the new task added to the run-queue preempts the current + * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets + * called on the nearest possible occasion: + * + * - If the kernel is preemptible (CONFIG_PREEMPTION=y): + * + * - in syscall or exception context, at the next outmost + * preempt_enable(). (this might be as soon as the wake_up()'s + * spin_unlock()!) + * + * - in IRQ context, return from interrupt-handler to + * preemptible context + * + * - If the kernel is not preemptible (CONFIG_PREEMPTION is not set) + * then at the next: + * + * - cond_resched() call + * - explicit schedule() call + * - return from syscall or exception to user-space + * - return from interrupt-handler to user-space + * + * WARNING: must be called with preemption disabled! + */ +static void __sched notrace __schedule(int sched_mode) +{ + struct task_struct *prev, *next; + /* + * On PREEMPT_RT kernel, SM_RTLOCK_WAIT is noted + * as a preemption by schedule_debug() and RCU. + */ + bool preempt = sched_mode > SM_NONE; + unsigned long *switch_count; + unsigned long prev_state; + struct rq *rq; + int cpu; + + cpu = smp_processor_id(); + rq = cpu_rq(cpu); + prev = rq->curr; + + schedule_debug(prev, preempt); + + /* by passing sched_feat(HRTICK) checking which Alt schedule FW doesn't support */ + hrtick_clear(rq); + + local_irq_disable(); + rcu_note_context_switch(preempt); + + /* + * Make sure that signal_pending_state()->signal_pending() below + * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) + * done by the caller to avoid the race with signal_wake_up(): + * + * __set_current_state(@state) signal_wake_up() + * schedule() set_tsk_thread_flag(p, TIF_SIGPENDING) + * wake_up_state(p, state) + * LOCK rq->lock LOCK p->pi_state + * smp_mb__after_spinlock() smp_mb__after_spinlock() + * if (signal_pending_state()) if (p->state & @state) + * + * Also, the membarrier system call requires a full memory barrier + * after coming from user-space, before storing to rq->curr; this + * barrier matches a full barrier in the proximity of the membarrier + * system call exit. + */ + raw_spin_lock(&rq->lock); + smp_mb__after_spinlock(); + + update_rq_clock(rq); + + switch_count = &prev->nivcsw; + + /* Task state changes only considers SM_PREEMPT as preemption */ + preempt = sched_mode == SM_PREEMPT; + + /* + * We must load prev->state once (task_struct::state is volatile), such + * that we form a control dependency vs deactivate_task() below. + */ + prev_state = READ_ONCE(prev->__state); + if (sched_mode == SM_IDLE) { + if (!rq->nr_running) { + next = prev; + goto picked; + } + } else if (!preempt && prev_state) { + try_to_block_task(rq, prev, prev_state); + switch_count = &prev->nvcsw; + } + + check_curr(prev, rq); + + next = choose_next_task(rq, cpu); +picked: + clear_tsk_need_resched(prev); + clear_preempt_need_resched(); +#ifdef CONFIG_SCHED_DEBUG + rq->last_seen_need_resched_ns = 0; +#endif + + if (likely(prev != next)) { + next->last_ran = rq->clock_task; + + /*printk(KERN_INFO "sched: %px -> %px\n", prev, next);*/ + rq->nr_switches++; + /* + * RCU users of rcu_dereference(rq->curr) may not see + * changes to task_struct made by pick_next_task(). + */ + RCU_INIT_POINTER(rq->curr, next); + /* + * The membarrier system call requires each architecture + * to have a full memory barrier after updating + * rq->curr, before returning to user-space. + * + * Here are the schemes providing that barrier on the + * various architectures: + * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, + * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() + * on PowerPC and on RISC-V. + * - finish_lock_switch() for weakly-ordered + * architectures where spin_unlock is a full barrier, + * - switch_to() for arm64 (weakly-ordered, spin_unlock + * is a RELEASE barrier), + * + * The barrier matches a full barrier in the proximity of + * the membarrier system call entry. + * + * On RISC-V, this barrier pairing is also needed for the + * SYNC_CORE command when switching between processes, cf. + * the inline comments in membarrier_arch_switch_mm(). + */ + ++*switch_count; + + trace_sched_switch(preempt, prev, next, prev_state); + + /* Also unlocks the rq: */ + rq = context_switch(rq, prev, next); + + cpu = cpu_of(rq); + } else { + __balance_callbacks(rq); + raw_spin_unlock_irq(&rq->lock); + } +} + +void __noreturn do_task_dead(void) +{ + /* Causes final put_task_struct in finish_task_switch(): */ + set_special_state(TASK_DEAD); + + /* Tell freezer to ignore us: */ + current->flags |= PF_NOFREEZE; + + __schedule(SM_NONE); + BUG(); + + /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */ + for (;;) + cpu_relax(); +} + +static inline void sched_submit_work(struct task_struct *tsk) +{ + static DEFINE_WAIT_OVERRIDE_MAP(sched_map, LD_WAIT_CONFIG); + unsigned int task_flags; + + /* + * Establish LD_WAIT_CONFIG context to ensure none of the code called + * will use a blocking primitive -- which would lead to recursion. + */ + lock_map_acquire_try(&sched_map); + + task_flags = tsk->flags; + /* + * If a worker goes to sleep, notify and ask workqueue whether it + * wants to wake up a task to maintain concurrency. + */ + if (task_flags & PF_WQ_WORKER) + wq_worker_sleeping(tsk); + else if (task_flags & PF_IO_WORKER) + io_wq_worker_sleeping(tsk); + + /* + * spinlock and rwlock must not flush block requests. This will + * deadlock if the callback attempts to acquire a lock which is + * already acquired. + */ + SCHED_WARN_ON(current->__state & TASK_RTLOCK_WAIT); + + /* + * If we are going to sleep and we have plugged IO queued, + * make sure to submit it to avoid deadlocks. + */ + blk_flush_plug(tsk->plug, true); + + lock_map_release(&sched_map); +} + +static void sched_update_worker(struct task_struct *tsk) +{ + if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER | PF_BLOCK_TS)) { + if (tsk->flags & PF_BLOCK_TS) + blk_plug_invalidate_ts(tsk); + if (tsk->flags & PF_WQ_WORKER) + wq_worker_running(tsk); + else if (tsk->flags & PF_IO_WORKER) + io_wq_worker_running(tsk); + } +} + +static __always_inline void __schedule_loop(int sched_mode) +{ + do { + preempt_disable(); + __schedule(sched_mode); + sched_preempt_enable_no_resched(); + } while (need_resched()); +} + +asmlinkage __visible void __sched schedule(void) +{ + struct task_struct *tsk = current; + +#ifdef CONFIG_RT_MUTEXES + lockdep_assert(!tsk->sched_rt_mutex); +#endif + + if (!task_is_running(tsk)) + sched_submit_work(tsk); + __schedule_loop(SM_NONE); + sched_update_worker(tsk); +} +EXPORT_SYMBOL(schedule); + +/* + * synchronize_rcu_tasks() makes sure that no task is stuck in preempted + * state (have scheduled out non-voluntarily) by making sure that all + * tasks have either left the run queue or have gone into user space. + * As idle tasks do not do either, they must not ever be preempted + * (schedule out non-voluntarily). + * + * schedule_idle() is similar to schedule_preempt_disable() except that it + * never enables preemption because it does not call sched_submit_work(). + */ +void __sched schedule_idle(void) +{ + /* + * As this skips calling sched_submit_work(), which the idle task does + * regardless because that function is a NOP when the task is in a + * TASK_RUNNING state, make sure this isn't used someplace that the + * current task can be in any other state. Note, idle is always in the + * TASK_RUNNING state. + */ + WARN_ON_ONCE(current->__state); + do { + __schedule(SM_IDLE); + } while (need_resched()); +} + +#if defined(CONFIG_CONTEXT_TRACKING_USER) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) +asmlinkage __visible void __sched schedule_user(void) +{ + /* + * If we come here after a random call to set_need_resched(), + * or we have been woken up remotely but the IPI has not yet arrived, + * we haven't yet exited the RCU idle mode. Do it here manually until + * we find a better solution. + * + * NB: There are buggy callers of this function. Ideally we + * should warn if prev_state != CT_STATE_USER, but that will trigger + * too frequently to make sense yet. + */ + enum ctx_state prev_state = exception_enter(); + schedule(); + exception_exit(prev_state); +} +#endif + +/** + * schedule_preempt_disabled - called with preemption disabled + * + * Returns with preemption disabled. Note: preempt_count must be 1 + */ +void __sched schedule_preempt_disabled(void) +{ + sched_preempt_enable_no_resched(); + schedule(); + preempt_disable(); +} + +#ifdef CONFIG_PREEMPT_RT +void __sched notrace schedule_rtlock(void) +{ + __schedule_loop(SM_RTLOCK_WAIT); +} +NOKPROBE_SYMBOL(schedule_rtlock); +#endif + +static void __sched notrace preempt_schedule_common(void) +{ + do { + /* + * Because the function tracer can trace preempt_count_sub() + * and it also uses preempt_enable/disable_notrace(), if + * NEED_RESCHED is set, the preempt_enable_notrace() called + * by the function tracer will call this function again and + * cause infinite recursion. + * + * Preemption must be disabled here before the function + * tracer can trace. Break up preempt_disable() into two + * calls. One to disable preemption without fear of being + * traced. The other to still record the preemption latency, + * which can also be traced by the function tracer. + */ + preempt_disable_notrace(); + preempt_latency_start(1); + __schedule(SM_PREEMPT); + preempt_latency_stop(1); + preempt_enable_no_resched_notrace(); + + /* + * Check again in case we missed a preemption opportunity + * between schedule and now. + */ + } while (need_resched()); +} + +#ifdef CONFIG_PREEMPTION +/* + * This is the entry point to schedule() from in-kernel preemption + * off of preempt_enable. + */ +asmlinkage __visible void __sched notrace preempt_schedule(void) +{ + /* + * If there is a non-zero preempt_count or interrupts are disabled, + * we do not want to preempt the current task. Just return.. + */ + if (likely(!preemptible())) + return; + + preempt_schedule_common(); +} +NOKPROBE_SYMBOL(preempt_schedule); +EXPORT_SYMBOL(preempt_schedule); + +#ifdef CONFIG_PREEMPT_DYNAMIC +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) +#ifndef preempt_schedule_dynamic_enabled +#define preempt_schedule_dynamic_enabled preempt_schedule +#define preempt_schedule_dynamic_disabled NULL +#endif +DEFINE_STATIC_CALL(preempt_schedule, preempt_schedule_dynamic_enabled); +EXPORT_STATIC_CALL_TRAMP(preempt_schedule); +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule); +void __sched notrace dynamic_preempt_schedule(void) +{ + if (!static_branch_unlikely(&sk_dynamic_preempt_schedule)) + return; + preempt_schedule(); +} +NOKPROBE_SYMBOL(dynamic_preempt_schedule); +EXPORT_SYMBOL(dynamic_preempt_schedule); +#endif +#endif + +/** + * preempt_schedule_notrace - preempt_schedule called by tracing + * + * The tracing infrastructure uses preempt_enable_notrace to prevent + * recursion and tracing preempt enabling caused by the tracing + * infrastructure itself. But as tracing can happen in areas coming + * from userspace or just about to enter userspace, a preempt enable + * can occur before user_exit() is called. This will cause the scheduler + * to be called when the system is still in usermode. + * + * To prevent this, the preempt_enable_notrace will use this function + * instead of preempt_schedule() to exit user context if needed before + * calling the scheduler. + */ +asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) +{ + enum ctx_state prev_ctx; + + if (likely(!preemptible())) + return; + + do { + /* + * Because the function tracer can trace preempt_count_sub() + * and it also uses preempt_enable/disable_notrace(), if + * NEED_RESCHED is set, the preempt_enable_notrace() called + * by the function tracer will call this function again and + * cause infinite recursion. + * + * Preemption must be disabled here before the function + * tracer can trace. Break up preempt_disable() into two + * calls. One to disable preemption without fear of being + * traced. The other to still record the preemption latency, + * which can also be traced by the function tracer. + */ + preempt_disable_notrace(); + preempt_latency_start(1); + /* + * Needs preempt disabled in case user_exit() is traced + * and the tracer calls preempt_enable_notrace() causing + * an infinite recursion. + */ + prev_ctx = exception_enter(); + __schedule(SM_PREEMPT); + exception_exit(prev_ctx); + + preempt_latency_stop(1); + preempt_enable_no_resched_notrace(); + } while (need_resched()); +} +EXPORT_SYMBOL_GPL(preempt_schedule_notrace); + +#ifdef CONFIG_PREEMPT_DYNAMIC +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) +#ifndef preempt_schedule_notrace_dynamic_enabled +#define preempt_schedule_notrace_dynamic_enabled preempt_schedule_notrace +#define preempt_schedule_notrace_dynamic_disabled NULL +#endif +DEFINE_STATIC_CALL(preempt_schedule_notrace, preempt_schedule_notrace_dynamic_enabled); +EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace); +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule_notrace); +void __sched notrace dynamic_preempt_schedule_notrace(void) +{ + if (!static_branch_unlikely(&sk_dynamic_preempt_schedule_notrace)) + return; + preempt_schedule_notrace(); +} +NOKPROBE_SYMBOL(dynamic_preempt_schedule_notrace); +EXPORT_SYMBOL(dynamic_preempt_schedule_notrace); +#endif +#endif + +#endif /* CONFIG_PREEMPTION */ + +/* + * This is the entry point to schedule() from kernel preemption + * off of IRQ context. + * Note, that this is called and return with IRQs disabled. This will + * protect us against recursive calling from IRQ contexts. + */ +asmlinkage __visible void __sched preempt_schedule_irq(void) +{ + enum ctx_state prev_state; + + /* Catch callers which need to be fixed */ + BUG_ON(preempt_count() || !irqs_disabled()); + + prev_state = exception_enter(); + + do { + preempt_disable(); + local_irq_enable(); + __schedule(SM_PREEMPT); + local_irq_disable(); + sched_preempt_enable_no_resched(); + } while (need_resched()); + + exception_exit(prev_state); +} + +int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags, + void *key) +{ + WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~(WF_SYNC|WF_CURRENT_CPU)); + return try_to_wake_up(curr->private, mode, wake_flags); +} +EXPORT_SYMBOL(default_wake_function); + +void check_task_changed(struct task_struct *p, struct rq *rq) +{ + /* Trigger resched if task sched_prio has been modified. */ + if (task_on_rq_queued(p)) { + update_rq_clock(rq); + requeue_task(p, rq); + wakeup_preempt(rq); + } +} + +void __setscheduler_prio(struct task_struct *p, int prio) +{ + p->prio = prio; +} + +#ifdef CONFIG_RT_MUTEXES + +/* + * Would be more useful with typeof()/auto_type but they don't mix with + * bit-fields. Since it's a local thing, use int. Keep the generic sounding + * name such that if someone were to implement this function we get to compare + * notes. + */ +#define fetch_and_set(x, v) ({ int _x = (x); (x) = (v); _x; }) + +void rt_mutex_pre_schedule(void) +{ + lockdep_assert(!fetch_and_set(current->sched_rt_mutex, 1)); + sched_submit_work(current); +} + +void rt_mutex_schedule(void) +{ + lockdep_assert(current->sched_rt_mutex); + __schedule_loop(SM_NONE); +} + +void rt_mutex_post_schedule(void) +{ + sched_update_worker(current); + lockdep_assert(fetch_and_set(current->sched_rt_mutex, 0)); +} + +/* + * rt_mutex_setprio - set the current priority of a task + * @p: task to boost + * @pi_task: donor task + * + * This function changes the 'effective' priority of a task. It does + * not touch ->normal_prio like __setscheduler(). + * + * Used by the rt_mutex code to implement priority inheritance + * logic. Call site only calls if the priority of the task changed. + */ +void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) +{ + int prio; + struct rq *rq; + raw_spinlock_t *lock; + + /* XXX used to be waiter->prio, not waiter->task->prio */ + prio = __rt_effective_prio(pi_task, p->normal_prio); + + /* + * If nothing changed; bail early. + */ + if (p->pi_top_task == pi_task && prio == p->prio) + return; + + rq = __task_access_lock(p, &lock); + /* + * Set under pi_lock && rq->lock, such that the value can be used under + * either lock. + * + * Note that there is loads of tricky to make this pointer cache work + * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to + * ensure a task is de-boosted (pi_task is set to NULL) before the + * task is allowed to run again (and can exit). This ensures the pointer + * points to a blocked task -- which guarantees the task is present. + */ + p->pi_top_task = pi_task; + + /* + * For FIFO/RR we only need to set prio, if that matches we're done. + */ + if (prio == p->prio) + goto out_unlock; + + /* + * Idle task boosting is a no-no in general. There is one + * exception, when PREEMPT_RT and NOHZ is active: + * + * The idle task calls get_next_timer_interrupt() and holds + * the timer wheel base->lock on the CPU and another CPU wants + * to access the timer (probably to cancel it). We can safely + * ignore the boosting request, as the idle CPU runs this code + * with interrupts disabled and will complete the lock + * protected section without being interrupted. So there is no + * real need to boost. + */ + if (unlikely(p == rq->idle)) { + WARN_ON(p != rq->curr); + WARN_ON(p->pi_blocked_on); + goto out_unlock; + } + + trace_sched_pi_setprio(p, pi_task); + + __setscheduler_prio(p, prio); + + check_task_changed(p, rq); +out_unlock: + /* Avoid rq from going away on us: */ + preempt_disable(); + + if (task_on_rq_queued(p)) + __balance_callbacks(rq); + __task_access_unlock(p, lock); + + preempt_enable(); +} +#endif + +#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) +int __sched __cond_resched(void) +{ + if (should_resched(0)) { + preempt_schedule_common(); + return 1; + } + /* + * In preemptible kernels, ->rcu_read_lock_nesting tells the tick + * whether the current CPU is in an RCU read-side critical section, + * so the tick can report quiescent states even for CPUs looping + * in kernel context. In contrast, in non-preemptible kernels, + * RCU readers leave no in-memory hints, which means that CPU-bound + * processes executing in kernel context might never report an + * RCU quiescent state. Therefore, the following code causes + * cond_resched() to report a quiescent state, but only when RCU + * is in urgent need of one. + */ +#ifndef CONFIG_PREEMPT_RCU + rcu_all_qs(); +#endif + return 0; +} +EXPORT_SYMBOL(__cond_resched); +#endif + +#ifdef CONFIG_PREEMPT_DYNAMIC +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) +#define cond_resched_dynamic_enabled __cond_resched +#define cond_resched_dynamic_disabled ((void *)&__static_call_return0) +DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(cond_resched); + +#define might_resched_dynamic_enabled __cond_resched +#define might_resched_dynamic_disabled ((void *)&__static_call_return0) +DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(might_resched); +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched); +int __sched dynamic_cond_resched(void) +{ + klp_sched_try_switch(); + if (!static_branch_unlikely(&sk_dynamic_cond_resched)) + return 0; + return __cond_resched(); +} +EXPORT_SYMBOL(dynamic_cond_resched); + +static DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched); +int __sched dynamic_might_resched(void) +{ + if (!static_branch_unlikely(&sk_dynamic_might_resched)) + return 0; + return __cond_resched(); +} +EXPORT_SYMBOL(dynamic_might_resched); +#endif +#endif + +/* + * __cond_resched_lock() - if a reschedule is pending, drop the given lock, + * call schedule, and on return reacquire the lock. + * + * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level + * operations here to prevent schedule() from being called twice (once via + * spin_unlock(), once by hand). + */ +int __cond_resched_lock(spinlock_t *lock) +{ + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held(lock); + + if (spin_needbreak(lock) || resched) { + spin_unlock(lock); + if (!_cond_resched()) + cpu_relax(); + ret = 1; + spin_lock(lock); + } + return ret; +} +EXPORT_SYMBOL(__cond_resched_lock); + +int __cond_resched_rwlock_read(rwlock_t *lock) +{ + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held_read(lock); + + if (rwlock_needbreak(lock) || resched) { + read_unlock(lock); + if (!_cond_resched()) + cpu_relax(); + ret = 1; + read_lock(lock); + } + return ret; +} +EXPORT_SYMBOL(__cond_resched_rwlock_read); + +int __cond_resched_rwlock_write(rwlock_t *lock) +{ + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held_write(lock); + + if (rwlock_needbreak(lock) || resched) { + write_unlock(lock); + if (!_cond_resched()) + cpu_relax(); + ret = 1; + write_lock(lock); + } + return ret; +} +EXPORT_SYMBOL(__cond_resched_rwlock_write); + +#ifdef CONFIG_PREEMPT_DYNAMIC + +#ifdef CONFIG_GENERIC_ENTRY +#include +#endif + +/* + * SC:cond_resched + * SC:might_resched + * SC:preempt_schedule + * SC:preempt_schedule_notrace + * SC:irqentry_exit_cond_resched + * + * + * NONE: + * cond_resched <- __cond_resched + * might_resched <- RET0 + * preempt_schedule <- NOP + * preempt_schedule_notrace <- NOP + * irqentry_exit_cond_resched <- NOP + * dynamic_preempt_lazy <- false + * + * VOLUNTARY: + * cond_resched <- __cond_resched + * might_resched <- __cond_resched + * preempt_schedule <- NOP + * preempt_schedule_notrace <- NOP + * irqentry_exit_cond_resched <- NOP + * dynamic_preempt_lazy <- false + * + * FULL: + * cond_resched <- RET0 + * might_resched <- RET0 + * preempt_schedule <- preempt_schedule + * preempt_schedule_notrace <- preempt_schedule_notrace + * irqentry_exit_cond_resched <- irqentry_exit_cond_resched + * dynamic_preempt_lazy <- false + * + * LAZY: + * cond_resched <- RET0 + * might_resched <- RET0 + * preempt_schedule <- preempt_schedule + * preempt_schedule_notrace <- preempt_schedule_notrace + * irqentry_exit_cond_resched <- irqentry_exit_cond_resched + * dynamic_preempt_lazy <- true + */ + +enum { + preempt_dynamic_undefined = -1, + preempt_dynamic_none, + preempt_dynamic_voluntary, + preempt_dynamic_full, + preempt_dynamic_lazy, +}; + +int preempt_dynamic_mode = preempt_dynamic_undefined; + +int sched_dynamic_mode(const char *str) +{ +#ifndef CONFIG_PREEMPT_RT + if (!strcmp(str, "none")) + return preempt_dynamic_none; + + if (!strcmp(str, "voluntary")) + return preempt_dynamic_voluntary; +#endif + + if (!strcmp(str, "full")) + return preempt_dynamic_full; + +#ifdef CONFIG_ARCH_HAS_PREEMPT_LAZY + if (!strcmp(str, "lazy")) + return preempt_dynamic_lazy; +#endif + + return -EINVAL; +} + +#define preempt_dynamic_key_enable(f) static_key_enable(&sk_dynamic_##f.key) +#define preempt_dynamic_key_disable(f) static_key_disable(&sk_dynamic_##f.key) + +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) +#define preempt_dynamic_enable(f) static_call_update(f, f##_dynamic_enabled) +#define preempt_dynamic_disable(f) static_call_update(f, f##_dynamic_disabled) +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +#define preempt_dynamic_enable(f) preempt_dynamic_key_enable(f) +#define preempt_dynamic_disable(f) preempt_dynamic_key_disable(f) +#else +#error "Unsupported PREEMPT_DYNAMIC mechanism" +#endif + +static DEFINE_MUTEX(sched_dynamic_mutex); +static bool klp_override; + +static void __sched_dynamic_update(int mode) +{ + /* + * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in + * the ZERO state, which is invalid. + */ + if (!klp_override) + preempt_dynamic_enable(cond_resched); + preempt_dynamic_enable(cond_resched); + preempt_dynamic_enable(might_resched); + preempt_dynamic_enable(preempt_schedule); + preempt_dynamic_enable(preempt_schedule_notrace); + preempt_dynamic_enable(irqentry_exit_cond_resched); + preempt_dynamic_key_disable(preempt_lazy); + + switch (mode) { + case preempt_dynamic_none: + if (!klp_override) + preempt_dynamic_enable(cond_resched); + preempt_dynamic_disable(might_resched); + preempt_dynamic_disable(preempt_schedule); + preempt_dynamic_disable(preempt_schedule_notrace); + preempt_dynamic_disable(irqentry_exit_cond_resched); + preempt_dynamic_key_disable(preempt_lazy); + if (mode != preempt_dynamic_mode) + pr_info("Dynamic Preempt: none\n"); + break; + + case preempt_dynamic_voluntary: + if (!klp_override) + preempt_dynamic_enable(cond_resched); + preempt_dynamic_enable(might_resched); + preempt_dynamic_disable(preempt_schedule); + preempt_dynamic_disable(preempt_schedule_notrace); + preempt_dynamic_disable(irqentry_exit_cond_resched); + preempt_dynamic_key_disable(preempt_lazy); + if (mode != preempt_dynamic_mode) + pr_info("Dynamic Preempt: voluntary\n"); + break; + + case preempt_dynamic_full: + if (!klp_override) + preempt_dynamic_enable(cond_resched); + preempt_dynamic_disable(might_resched); + preempt_dynamic_enable(preempt_schedule); + preempt_dynamic_enable(preempt_schedule_notrace); + preempt_dynamic_enable(irqentry_exit_cond_resched); + preempt_dynamic_key_disable(preempt_lazy); + if (mode != preempt_dynamic_mode) + pr_info("Dynamic Preempt: full\n"); + break; + + case preempt_dynamic_lazy: + if (!klp_override) + preempt_dynamic_disable(cond_resched); + preempt_dynamic_disable(might_resched); + preempt_dynamic_enable(preempt_schedule); + preempt_dynamic_enable(preempt_schedule_notrace); + preempt_dynamic_enable(irqentry_exit_cond_resched); + preempt_dynamic_key_enable(preempt_lazy); + if (mode != preempt_dynamic_mode) + pr_info("Dynamic Preempt: lazy\n"); + break; + } + + preempt_dynamic_mode = mode; +} + +void sched_dynamic_update(int mode) +{ + mutex_lock(&sched_dynamic_mutex); + __sched_dynamic_update(mode); + mutex_unlock(&sched_dynamic_mutex); +} + +#ifdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL + +static int klp_cond_resched(void) +{ + __klp_sched_try_switch(); + return __cond_resched(); +} + +void sched_dynamic_klp_enable(void) +{ + mutex_lock(&sched_dynamic_mutex); + + klp_override = true; + static_call_update(cond_resched, klp_cond_resched); + + mutex_unlock(&sched_dynamic_mutex); +} + +void sched_dynamic_klp_disable(void) +{ + mutex_lock(&sched_dynamic_mutex); + + klp_override = false; + __sched_dynamic_update(preempt_dynamic_mode); + + mutex_unlock(&sched_dynamic_mutex); +} + +#endif /* CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */ + + +static int __init setup_preempt_mode(char *str) +{ + int mode = sched_dynamic_mode(str); + if (mode < 0) { + pr_warn("Dynamic Preempt: unsupported mode: %s\n", str); + return 0; + } + + sched_dynamic_update(mode); + return 1; +} +__setup("preempt=", setup_preempt_mode); + +static void __init preempt_dynamic_init(void) +{ + if (preempt_dynamic_mode == preempt_dynamic_undefined) { + if (IS_ENABLED(CONFIG_PREEMPT_NONE)) { + sched_dynamic_update(preempt_dynamic_none); + } else if (IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY)) { + sched_dynamic_update(preempt_dynamic_voluntary); + } else if (IS_ENABLED(CONFIG_PREEMPT_LAZY)) { + sched_dynamic_update(preempt_dynamic_lazy); + } else { + /* Default static call setting, nothing to do */ + WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT)); + preempt_dynamic_mode = preempt_dynamic_full; + pr_info("Dynamic Preempt: full\n"); + } + } +} + +#define PREEMPT_MODEL_ACCESSOR(mode) \ + bool preempt_model_##mode(void) \ + { \ + WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \ + return preempt_dynamic_mode == preempt_dynamic_##mode; \ + } \ + EXPORT_SYMBOL_GPL(preempt_model_##mode) + +PREEMPT_MODEL_ACCESSOR(none); +PREEMPT_MODEL_ACCESSOR(voluntary); +PREEMPT_MODEL_ACCESSOR(full); +PREEMPT_MODEL_ACCESSOR(lazy); + +#else /* !CONFIG_PREEMPT_DYNAMIC: */ + +static inline void preempt_dynamic_init(void) { } + +#endif /* CONFIG_PREEMPT_DYNAMIC */ + +int io_schedule_prepare(void) +{ + int old_iowait = current->in_iowait; + + current->in_iowait = 1; + blk_flush_plug(current->plug, true); + return old_iowait; +} + +void io_schedule_finish(int token) +{ + current->in_iowait = token; +} + +/* + * This task is about to go to sleep on IO. Increment rq->nr_iowait so + * that process accounting knows that this is a task in IO wait state. + * + * But don't do that if it is a deliberate, throttling IO wait (this task + * has set its backing_dev_info: the queue against which it should throttle) + */ + +long __sched io_schedule_timeout(long timeout) +{ + int token; + long ret; + + token = io_schedule_prepare(); + ret = schedule_timeout(timeout); + io_schedule_finish(token); + + return ret; +} +EXPORT_SYMBOL(io_schedule_timeout); + +void __sched io_schedule(void) +{ + int token; + + token = io_schedule_prepare(); + schedule(); + io_schedule_finish(token); +} +EXPORT_SYMBOL(io_schedule); + +void sched_show_task(struct task_struct *p) +{ + unsigned long free; + int ppid; + + if (!try_get_task_stack(p)) + return; + + pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p)); + + if (task_is_running(p)) + pr_cont(" running task "); + free = stack_not_used(p); + ppid = 0; + rcu_read_lock(); + if (pid_alive(p)) + ppid = task_pid_nr(rcu_dereference(p->real_parent)); + rcu_read_unlock(); + pr_cont(" stack:%-5lu pid:%-5d tgid:%-5d ppid:%-6d flags:0x%08lx\n", + free, task_pid_nr(p), task_tgid_nr(p), + ppid, read_task_thread_flags(p)); + + print_worker_info(KERN_INFO, p); + print_stop_info(KERN_INFO, p); + show_stack(p, NULL, KERN_INFO); + put_task_stack(p); +} +EXPORT_SYMBOL_GPL(sched_show_task); + +static inline bool +state_filter_match(unsigned long state_filter, struct task_struct *p) +{ + unsigned int state = READ_ONCE(p->__state); + + /* no filter, everything matches */ + if (!state_filter) + return true; + + /* filter, but doesn't match */ + if (!(state & state_filter)) + return false; + + /* + * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows + * TASK_KILLABLE). + */ + if (state_filter == TASK_UNINTERRUPTIBLE && (state & TASK_NOLOAD)) + return false; + + return true; +} + + +void show_state_filter(unsigned int state_filter) +{ + struct task_struct *g, *p; + + rcu_read_lock(); + for_each_process_thread(g, p) { + /* + * reset the NMI-timeout, listing all files on a slow + * console might take a lot of time: + * Also, reset softlockup watchdogs on all CPUs, because + * another CPU might be blocked waiting for us to process + * an IPI. + */ + touch_nmi_watchdog(); + touch_all_softlockup_watchdogs(); + if (state_filter_match(state_filter, p)) + sched_show_task(p); + } + +#ifdef CONFIG_SCHED_DEBUG + /* TODO: Alt schedule FW should support this + if (!state_filter) + sysrq_sched_debug_show(); + */ +#endif + rcu_read_unlock(); + /* + * Only show locks if all tasks are dumped: + */ + if (!state_filter) + debug_show_all_locks(); +} + +void dump_cpu_task(int cpu) +{ + if (in_hardirq() && cpu == smp_processor_id()) { + struct pt_regs *regs; + + regs = get_irq_regs(); + if (regs) { + show_regs(regs); + return; + } + } + + if (trigger_single_cpu_backtrace(cpu)) + return; + + pr_info("Task dump for CPU %d:\n", cpu); + sched_show_task(cpu_curr(cpu)); +} + +/** + * init_idle - set up an idle thread for a given CPU + * @idle: task in question + * @cpu: CPU the idle task belongs to + * + * NOTE: this function does not set the idle thread's NEED_RESCHED + * flag, to make booting more robust. + */ +void __init init_idle(struct task_struct *idle, int cpu) +{ +#ifdef CONFIG_SMP + struct affinity_context ac = (struct affinity_context) { + .new_mask = cpumask_of(cpu), + .flags = 0, + }; +#endif + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + + raw_spin_lock_irqsave(&idle->pi_lock, flags); + raw_spin_lock(&rq->lock); + + idle->last_ran = rq->clock_task; + idle->__state = TASK_RUNNING; + /* + * PF_KTHREAD should already be set at this point; regardless, make it + * look like a proper per-CPU kthread. + */ + idle->flags |= PF_KTHREAD | PF_NO_SETAFFINITY; + kthread_set_per_cpu(idle, cpu); + + sched_queue_init_idle(&rq->queue, idle); + +#ifdef CONFIG_SMP + /* + * No validation and serialization required at boot time and for + * setting up the idle tasks of not yet online CPUs. + */ + set_cpus_allowed_common(idle, &ac); +#endif + + /* Silence PROVE_RCU */ + rcu_read_lock(); + __set_task_cpu(idle, cpu); + rcu_read_unlock(); + + rq->idle = idle; + rcu_assign_pointer(rq->curr, idle); + idle->on_cpu = 1; + + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&idle->pi_lock, flags); + + /* Set the preempt count _outside_ the spinlocks! */ + init_idle_preempt_count(idle, cpu); + + ftrace_graph_init_idle_task(idle, cpu); + vtime_init_idle(idle, cpu); +#ifdef CONFIG_SMP + sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); +#endif +} + +#ifdef CONFIG_SMP + +int cpuset_cpumask_can_shrink(const struct cpumask __maybe_unused *cur, + const struct cpumask __maybe_unused *trial) +{ + return 1; +} + +int task_can_attach(struct task_struct *p) +{ + int ret = 0; + + /* + * Kthreads which disallow setaffinity shouldn't be moved + * to a new cpuset; we don't want to change their CPU + * affinity and isolating such threads by their set of + * allowed nodes is unnecessary. Thus, cpusets are not + * applicable for such threads. This prevents checking for + * success of set_cpus_allowed_ptr() on all attached tasks + * before cpus_mask may be changed. + */ + if (p->flags & PF_NO_SETAFFINITY) + ret = -EINVAL; + + return ret; +} + +bool sched_smp_initialized __read_mostly; + +#ifdef CONFIG_HOTPLUG_CPU +/* + * Ensures that the idle task is using init_mm right before its CPU goes + * offline. + */ +void idle_task_exit(void) +{ + struct mm_struct *mm = current->active_mm; + + BUG_ON(current != this_rq()->idle); + + if (mm != &init_mm) { + switch_mm(mm, &init_mm, current); + finish_arch_post_lock_switch(); + } + + /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ +} + +static int __balance_push_cpu_stop(void *arg) +{ + struct task_struct *p = arg; + struct rq *rq = this_rq(); + struct rq_flags rf; + int cpu; + + raw_spin_lock_irq(&p->pi_lock); + rq_lock(rq, &rf); + + update_rq_clock(rq); + + if (task_rq(p) == rq && task_on_rq_queued(p)) { + cpu = select_fallback_rq(rq->cpu, p); + rq = __migrate_task(rq, p, cpu); + } + + rq_unlock(rq, &rf); + raw_spin_unlock_irq(&p->pi_lock); + + put_task_struct(p); + + return 0; +} + +static DEFINE_PER_CPU(struct cpu_stop_work, push_work); + +/* + * This is enabled below SCHED_AP_ACTIVE; when !cpu_active(), but only + * effective when the hotplug motion is down. + */ +static void balance_push(struct rq *rq) +{ + struct task_struct *push_task = rq->curr; + + lockdep_assert_held(&rq->lock); + + /* + * Ensure the thing is persistent until balance_push_set(.on = false); + */ + rq->balance_callback = &balance_push_callback; + + /* + * Only active while going offline and when invoked on the outgoing + * CPU. + */ + if (!cpu_dying(rq->cpu) || rq != this_rq()) + return; + + /* + * Both the cpu-hotplug and stop task are in this case and are + * required to complete the hotplug process. + */ + if (kthread_is_per_cpu(push_task) || + is_migration_disabled(push_task)) { + + /* + * If this is the idle task on the outgoing CPU try to wake + * up the hotplug control thread which might wait for the + * last task to vanish. The rcuwait_active() check is + * accurate here because the waiter is pinned on this CPU + * and can't obviously be running in parallel. + * + * On RT kernels this also has to check whether there are + * pinned and scheduled out tasks on the runqueue. They + * need to leave the migrate disabled section first. + */ + if (!rq->nr_running && !rq_has_pinned_tasks(rq) && + rcuwait_active(&rq->hotplug_wait)) { + raw_spin_unlock(&rq->lock); + rcuwait_wake_up(&rq->hotplug_wait); + raw_spin_lock(&rq->lock); + } + return; + } + + get_task_struct(push_task); + /* + * Temporarily drop rq->lock such that we can wake-up the stop task. + * Both preemption and IRQs are still disabled. + */ + preempt_disable(); + raw_spin_unlock(&rq->lock); + stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task, + this_cpu_ptr(&push_work)); + preempt_enable(); + /* + * At this point need_resched() is true and we'll take the loop in + * schedule(). The next pick is obviously going to be the stop task + * which kthread_is_per_cpu() and will push this task away. + */ + raw_spin_lock(&rq->lock); +} + +static void balance_push_set(int cpu, bool on) +{ + struct rq *rq = cpu_rq(cpu); + struct rq_flags rf; + + rq_lock_irqsave(rq, &rf); + if (on) { + WARN_ON_ONCE(rq->balance_callback); + rq->balance_callback = &balance_push_callback; + } else if (rq->balance_callback == &balance_push_callback) { + rq->balance_callback = NULL; + } + rq_unlock_irqrestore(rq, &rf); +} + +/* + * Invoked from a CPUs hotplug control thread after the CPU has been marked + * inactive. All tasks which are not per CPU kernel threads are either + * pushed off this CPU now via balance_push() or placed on a different CPU + * during wakeup. Wait until the CPU is quiescent. + */ +static void balance_hotplug_wait(void) +{ + struct rq *rq = this_rq(); + + rcuwait_wait_event(&rq->hotplug_wait, + rq->nr_running == 1 && !rq_has_pinned_tasks(rq), + TASK_UNINTERRUPTIBLE); +} + +#else + +static void balance_push(struct rq *rq) +{ +} + +static void balance_push_set(int cpu, bool on) +{ +} + +static inline void balance_hotplug_wait(void) +{ +} +#endif /* CONFIG_HOTPLUG_CPU */ + +static void set_rq_offline(struct rq *rq) +{ + if (rq->online) { + update_rq_clock(rq); + rq->online = false; + } +} + +static void set_rq_online(struct rq *rq) +{ + if (!rq->online) + rq->online = true; +} + +static inline void sched_set_rq_online(struct rq *rq, int cpu) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&rq->lock, flags); + set_rq_online(rq); + raw_spin_unlock_irqrestore(&rq->lock, flags); +} + +static inline void sched_set_rq_offline(struct rq *rq, int cpu) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&rq->lock, flags); + set_rq_offline(rq); + raw_spin_unlock_irqrestore(&rq->lock, flags); +} + +/* + * used to mark begin/end of suspend/resume: + */ +static int num_cpus_frozen; + +/* + * Update cpusets according to cpu_active mask. If cpusets are + * disabled, cpuset_update_active_cpus() becomes a simple wrapper + * around partition_sched_domains(). + * + * If we come here as part of a suspend/resume, don't touch cpusets because we + * want to restore it back to its original state upon resume anyway. + */ +static void cpuset_cpu_active(void) +{ + if (cpuhp_tasks_frozen) { + /* + * num_cpus_frozen tracks how many CPUs are involved in suspend + * resume sequence. As long as this is not the last online + * operation in the resume sequence, just build a single sched + * domain, ignoring cpusets. + */ + partition_sched_domains(1, NULL, NULL); + if (--num_cpus_frozen) + return; + /* + * This is the last CPU online operation. So fall through and + * restore the original sched domains by considering the + * cpuset configurations. + */ + cpuset_force_rebuild(); + } + + cpuset_update_active_cpus(); +} + +static int cpuset_cpu_inactive(unsigned int cpu) +{ + if (!cpuhp_tasks_frozen) { + cpuset_update_active_cpus(); + } else { + num_cpus_frozen++; + partition_sched_domains(1, NULL, NULL); + } + return 0; +} + +static inline void sched_smt_present_inc(int cpu) +{ +#ifdef CONFIG_SCHED_SMT + if (cpumask_weight(cpu_smt_mask(cpu)) == 2) { + static_branch_inc_cpuslocked(&sched_smt_present); + cpumask_or(&sched_smt_mask, &sched_smt_mask, cpu_smt_mask(cpu)); + } +#endif +} + +static inline void sched_smt_present_dec(int cpu) +{ +#ifdef CONFIG_SCHED_SMT + if (cpumask_weight(cpu_smt_mask(cpu)) == 2) { + static_branch_dec_cpuslocked(&sched_smt_present); + if (!static_branch_likely(&sched_smt_present)) + cpumask_clear(sched_pcore_idle_mask); + cpumask_andnot(&sched_smt_mask, &sched_smt_mask, cpu_smt_mask(cpu)); + } +#endif +} + +int sched_cpu_activate(unsigned int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + /* + * Clear the balance_push callback and prepare to schedule + * regular tasks. + */ + balance_push_set(cpu, false); + + set_cpu_active(cpu, true); + + if (sched_smp_initialized) + cpuset_cpu_active(); + + /* + * Put the rq online, if not already. This happens: + * + * 1) In the early boot process, because we build the real domains + * after all cpus have been brought up. + * + * 2) At runtime, if cpuset_cpu_active() fails to rebuild the + * domains. + */ + sched_set_rq_online(rq, cpu); + + /* + * When going up, increment the number of cores with SMT present. + */ + sched_smt_present_inc(cpu); + + return 0; +} + +int sched_cpu_deactivate(unsigned int cpu) +{ + struct rq *rq = cpu_rq(cpu); + int ret; + + set_cpu_active(cpu, false); + + /* + * From this point forward, this CPU will refuse to run any task that + * is not: migrate_disable() or KTHREAD_IS_PER_CPU, and will actively + * push those tasks away until this gets cleared, see + * sched_cpu_dying(). + */ + balance_push_set(cpu, true); + + /* + * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU + * users of this state to go away such that all new such users will + * observe it. + * + * Specifically, we rely on ttwu to no longer target this CPU, see + * ttwu_queue_cond() and is_cpu_allowed(). + * + * Do sync before park smpboot threads to take care the RCU boost case. + */ + synchronize_rcu(); + + sched_set_rq_offline(rq, cpu); + + /* + * When going down, decrement the number of cores with SMT present. + */ + sched_smt_present_dec(cpu); + + if (!sched_smp_initialized) + return 0; + + ret = cpuset_cpu_inactive(cpu); + if (ret) { + sched_smt_present_inc(cpu); + sched_set_rq_online(rq, cpu); + balance_push_set(cpu, false); + set_cpu_active(cpu, true); + return ret; + } + + return 0; +} + +static void sched_rq_cpu_starting(unsigned int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + rq->calc_load_update = calc_load_update; +} + +int sched_cpu_starting(unsigned int cpu) +{ + sched_rq_cpu_starting(cpu); + sched_tick_start(cpu); + return 0; +} + +#ifdef CONFIG_HOTPLUG_CPU + +/* + * Invoked immediately before the stopper thread is invoked to bring the + * CPU down completely. At this point all per CPU kthreads except the + * hotplug thread (current) and the stopper thread (inactive) have been + * either parked or have been unbound from the outgoing CPU. Ensure that + * any of those which might be on the way out are gone. + * + * If after this point a bound task is being woken on this CPU then the + * responsible hotplug callback has failed to do it's job. + * sched_cpu_dying() will catch it with the appropriate fireworks. + */ +int sched_cpu_wait_empty(unsigned int cpu) +{ + balance_hotplug_wait(); + return 0; +} + +/* + * Since this CPU is going 'away' for a while, fold any nr_active delta we + * might have. Called from the CPU stopper task after ensuring that the + * stopper is the last running task on the CPU, so nr_active count is + * stable. We need to take the tear-down thread which is calling this into + * account, so we hand in adjust = 1 to the load calculation. + * + * Also see the comment "Global load-average calculations". + */ +static void calc_load_migrate(struct rq *rq) +{ + long delta = calc_load_fold_active(rq, 1); + + if (delta) + atomic_long_add(delta, &calc_load_tasks); +} + +static void dump_rq_tasks(struct rq *rq, const char *loglvl) +{ + struct task_struct *g, *p; + int cpu = cpu_of(rq); + + lockdep_assert_held(&rq->lock); + + printk("%sCPU%d enqueued tasks (%u total):\n", loglvl, cpu, rq->nr_running); + for_each_process_thread(g, p) { + if (task_cpu(p) != cpu) + continue; + + if (!task_on_rq_queued(p)) + continue; + + printk("%s\tpid: %d, name: %s\n", loglvl, p->pid, p->comm); + } +} + +int sched_cpu_dying(unsigned int cpu) +{ + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + + /* Handle pending wakeups and then migrate everything off */ + sched_tick_stop(cpu); + + raw_spin_lock_irqsave(&rq->lock, flags); + if (rq->nr_running != 1 || rq_has_pinned_tasks(rq)) { + WARN(true, "Dying CPU not properly vacated!"); + dump_rq_tasks(rq, KERN_WARNING); + } + raw_spin_unlock_irqrestore(&rq->lock, flags); + + calc_load_migrate(rq); + hrtick_clear(rq); + return 0; +} +#endif + +#ifdef CONFIG_SMP +static void sched_init_topology_cpumask_early(void) +{ + int cpu; + cpumask_t *tmp; + + for_each_possible_cpu(cpu) { + /* init topo masks */ + tmp = per_cpu(sched_cpu_topo_masks, cpu); + + cpumask_copy(tmp, cpu_possible_mask); + per_cpu(sched_cpu_llc_mask, cpu) = tmp; + per_cpu(sched_cpu_topo_end_mask, cpu) = ++tmp; + } +} + +#define TOPOLOGY_CPUMASK(name, mask, last)\ + if (cpumask_and(topo, topo, mask)) { \ + cpumask_copy(topo, mask); \ + printk(KERN_INFO "sched: cpu#%02d topo: 0x%08lx - "#name, \ + cpu, (topo++)->bits[0]); \ + } \ + if (!last) \ + bitmap_complement(cpumask_bits(topo), cpumask_bits(mask), \ + nr_cpumask_bits); + +static void sched_init_topology_cpumask(void) +{ + int cpu; + cpumask_t *topo; + + for_each_online_cpu(cpu) { + topo = per_cpu(sched_cpu_topo_masks, cpu); + + bitmap_complement(cpumask_bits(topo), cpumask_bits(cpumask_of(cpu)), + nr_cpumask_bits); +#ifdef CONFIG_SCHED_SMT + TOPOLOGY_CPUMASK(smt, topology_sibling_cpumask(cpu), false); +#endif + TOPOLOGY_CPUMASK(cluster, topology_cluster_cpumask(cpu), false); + + per_cpu(sd_llc_id, cpu) = cpumask_first(cpu_coregroup_mask(cpu)); + per_cpu(sched_cpu_llc_mask, cpu) = topo; + TOPOLOGY_CPUMASK(coregroup, cpu_coregroup_mask(cpu), false); + + TOPOLOGY_CPUMASK(core, topology_core_cpumask(cpu), false); + + TOPOLOGY_CPUMASK(others, cpu_online_mask, true); + + per_cpu(sched_cpu_topo_end_mask, cpu) = topo; + printk(KERN_INFO "sched: cpu#%02d llc_id = %d, llc_mask idx = %d\n", + cpu, per_cpu(sd_llc_id, cpu), + (int) (per_cpu(sched_cpu_llc_mask, cpu) - + per_cpu(sched_cpu_topo_masks, cpu))); + } +} +#endif + +void __init sched_init_smp(void) +{ + /* Move init over to a non-isolated CPU */ + if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_DOMAIN)) < 0) + BUG(); + current->flags &= ~PF_NO_SETAFFINITY; + + sched_init_topology(); + sched_init_topology_cpumask(); + + sched_smp_initialized = true; +} + +static int __init migration_init(void) +{ + sched_cpu_starting(smp_processor_id()); + return 0; +} +early_initcall(migration_init); + +#else +void __init sched_init_smp(void) +{ + cpu_rq(0)->idle->time_slice = sysctl_sched_base_slice; +} +#endif /* CONFIG_SMP */ + +int in_sched_functions(unsigned long addr) +{ + return in_lock_functions(addr) || + (addr >= (unsigned long)__sched_text_start + && addr < (unsigned long)__sched_text_end); +} + +#ifdef CONFIG_CGROUP_SCHED +/* + * Default task group. + * Every task in system belongs to this group at bootup. + */ +struct task_group root_task_group; +LIST_HEAD(task_groups); + +/* Cacheline aligned slab cache for task_group */ +static struct kmem_cache *task_group_cache __ro_after_init; +#endif /* CONFIG_CGROUP_SCHED */ + +void __init sched_init(void) +{ + int i; + struct rq *rq; + + printk(KERN_INFO "sched/alt: "ALT_SCHED_NAME" CPU Scheduler "ALT_SCHED_VERSION\ + " by Alfred Chen.\n"); + + wait_bit_init(); + +#ifdef CONFIG_SMP + for (i = 0; i < SCHED_QUEUE_BITS; i++) + cpumask_copy(sched_preempt_mask + i, cpu_present_mask); +#endif + +#ifdef CONFIG_CGROUP_SCHED + task_group_cache = KMEM_CACHE(task_group, 0); + + list_add(&root_task_group.list, &task_groups); + INIT_LIST_HEAD(&root_task_group.children); + INIT_LIST_HEAD(&root_task_group.siblings); +#endif /* CONFIG_CGROUP_SCHED */ + for_each_possible_cpu(i) { + rq = cpu_rq(i); + + sched_queue_init(&rq->queue); + rq->prio = IDLE_TASK_SCHED_PRIO; +#ifdef CONFIG_SCHED_PDS + rq->prio_idx = rq->prio; +#endif + + raw_spin_lock_init(&rq->lock); + rq->nr_running = rq->nr_uninterruptible = 0; + rq->calc_load_active = 0; + rq->calc_load_update = jiffies + LOAD_FREQ; +#ifdef CONFIG_SMP + rq->online = false; + rq->cpu = i; + + rq->clear_idle_mask_func = cpumask_clear_cpu; + rq->set_idle_mask_func = cpumask_set_cpu; + rq->balance_func = NULL; + rq->active_balance_arg.active = 0; + +#ifdef CONFIG_NO_HZ_COMMON + INIT_CSD(&rq->nohz_csd, nohz_csd_func, rq); +#endif + rq->balance_callback = &balance_push_callback; +#ifdef CONFIG_HOTPLUG_CPU + rcuwait_init(&rq->hotplug_wait); +#endif +#endif /* CONFIG_SMP */ + rq->nr_switches = 0; + + hrtick_rq_init(rq); + atomic_set(&rq->nr_iowait, 0); + + zalloc_cpumask_var_node(&rq->scratch_mask, GFP_KERNEL, cpu_to_node(i)); + } +#ifdef CONFIG_SMP + /* Set rq->online for cpu 0 */ + cpu_rq(0)->online = true; +#endif + /* + * The boot idle thread does lazy MMU switching as well: + */ + mmgrab(&init_mm); + enter_lazy_tlb(&init_mm, current); + + /* + * The idle task doesn't need the kthread struct to function, but it + * is dressed up as a per-CPU kthread and thus needs to play the part + * if we want to avoid special-casing it in code that deals with per-CPU + * kthreads. + */ + WARN_ON(!set_kthread_struct(current)); + + /* + * Make us the idle thread. Technically, schedule() should not be + * called from this thread, however somewhere below it might be, + * but because we are the idle thread, we just pick up running again + * when this runqueue becomes "idle". + */ + __sched_fork(0, current); + init_idle(current, smp_processor_id()); + + calc_load_update = jiffies + LOAD_FREQ; + +#ifdef CONFIG_SMP + idle_thread_set_boot_cpu(); + balance_push_set(smp_processor_id(), false); + + sched_init_topology_cpumask_early(); +#endif /* SMP */ + + preempt_dynamic_init(); +} + +#ifdef CONFIG_DEBUG_ATOMIC_SLEEP + +void __might_sleep(const char *file, int line) +{ + unsigned int state = get_current_state(); + /* + * Blocking primitives will set (and therefore destroy) current->state, + * since we will exit with TASK_RUNNING make sure we enter with it, + * otherwise we will destroy state. + */ + WARN_ONCE(state != TASK_RUNNING && current->task_state_change, + "do not call blocking ops when !TASK_RUNNING; " + "state=%x set at [<%p>] %pS\n", state, + (void *)current->task_state_change, + (void *)current->task_state_change); + + __might_resched(file, line, 0); +} +EXPORT_SYMBOL(__might_sleep); + +static void print_preempt_disable_ip(int preempt_offset, unsigned long ip) +{ + if (!IS_ENABLED(CONFIG_DEBUG_PREEMPT)) + return; + + if (preempt_count() == preempt_offset) + return; + + pr_err("Preemption disabled at:"); + print_ip_sym(KERN_ERR, ip); +} + +static inline bool resched_offsets_ok(unsigned int offsets) +{ + unsigned int nested = preempt_count(); + + nested += rcu_preempt_depth() << MIGHT_RESCHED_RCU_SHIFT; + + return nested == offsets; +} + +void __might_resched(const char *file, int line, unsigned int offsets) +{ + /* Ratelimiting timestamp: */ + static unsigned long prev_jiffy; + + unsigned long preempt_disable_ip; + + /* WARN_ON_ONCE() by default, no rate limit required: */ + rcu_sleep_check(); + + if ((resched_offsets_ok(offsets) && !irqs_disabled() && + !is_idle_task(current) && !current->non_block_count) || + system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || + oops_in_progress) + return; + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) + return; + prev_jiffy = jiffies; + + /* Save this before calling printk(), since that will clobber it: */ + preempt_disable_ip = get_preempt_disable_ip(current); + + pr_err("BUG: sleeping function called from invalid context at %s:%d\n", + file, line); + pr_err("in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n", + in_atomic(), irqs_disabled(), current->non_block_count, + current->pid, current->comm); + pr_err("preempt_count: %x, expected: %x\n", preempt_count(), + offsets & MIGHT_RESCHED_PREEMPT_MASK); + + if (IS_ENABLED(CONFIG_PREEMPT_RCU)) { + pr_err("RCU nest depth: %d, expected: %u\n", + rcu_preempt_depth(), offsets >> MIGHT_RESCHED_RCU_SHIFT); + } + + if (task_stack_end_corrupted(current)) + pr_emerg("Thread overran stack, or stack corrupted\n"); + + debug_show_held_locks(current); + if (irqs_disabled()) + print_irqtrace_events(current); + + print_preempt_disable_ip(offsets & MIGHT_RESCHED_PREEMPT_MASK, + preempt_disable_ip); + + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); +} +EXPORT_SYMBOL(__might_resched); + +void __cant_sleep(const char *file, int line, int preempt_offset) +{ + static unsigned long prev_jiffy; + + if (irqs_disabled()) + return; + + if (!IS_ENABLED(CONFIG_PREEMPT_COUNT)) + return; + + if (preempt_count() > preempt_offset) + return; + + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) + return; + prev_jiffy = jiffies; + + printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line); + printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", + in_atomic(), irqs_disabled(), + current->pid, current->comm); + + debug_show_held_locks(current); + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); +} +EXPORT_SYMBOL_GPL(__cant_sleep); + +#ifdef CONFIG_SMP +void __cant_migrate(const char *file, int line) +{ + static unsigned long prev_jiffy; + + if (irqs_disabled()) + return; + + if (is_migration_disabled(current)) + return; + + if (!IS_ENABLED(CONFIG_PREEMPT_COUNT)) + return; + + if (preempt_count() > 0) + return; + + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) + return; + prev_jiffy = jiffies; + + pr_err("BUG: assuming non migratable context at %s:%d\n", file, line); + pr_err("in_atomic(): %d, irqs_disabled(): %d, migration_disabled() %u pid: %d, name: %s\n", + in_atomic(), irqs_disabled(), is_migration_disabled(current), + current->pid, current->comm); + + debug_show_held_locks(current); + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); +} +EXPORT_SYMBOL_GPL(__cant_migrate); +#endif +#endif + +#ifdef CONFIG_MAGIC_SYSRQ +void normalize_rt_tasks(void) +{ + struct task_struct *g, *p; + struct sched_attr attr = { + .sched_policy = SCHED_NORMAL, + }; + + read_lock(&tasklist_lock); + for_each_process_thread(g, p) { + /* + * Only normalize user tasks: + */ + if (p->flags & PF_KTHREAD) + continue; + + schedstat_set(p->stats.wait_start, 0); + schedstat_set(p->stats.sleep_start, 0); + schedstat_set(p->stats.block_start, 0); + + if (!rt_or_dl_task(p)) { + /* + * Renice negative nice level userspace + * tasks back to 0: + */ + if (task_nice(p) < 0) + set_user_nice(p, 0); + continue; + } + + __sched_setscheduler(p, &attr, false, false); + } + read_unlock(&tasklist_lock); +} +#endif /* CONFIG_MAGIC_SYSRQ */ + +#if defined(CONFIG_KGDB_KDB) +/* + * These functions are only useful for KDB. + * + * They can only be called when the whole system has been + * stopped - every CPU needs to be quiescent, and no scheduling + * activity can take place. Using them for anything else would + * be a serious bug, and as a result, they aren't even visible + * under any other configuration. + */ + +/** + * curr_task - return the current task for a given CPU. + * @cpu: the processor in question. + * + * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! + * + * Return: The current task for @cpu. + */ +struct task_struct *curr_task(int cpu) +{ + return cpu_curr(cpu); +} + +#endif /* defined(CONFIG_KGDB_KDB) */ + +#ifdef CONFIG_CGROUP_SCHED +static void sched_free_group(struct task_group *tg) +{ + kmem_cache_free(task_group_cache, tg); +} + +static void sched_free_group_rcu(struct rcu_head *rhp) +{ + sched_free_group(container_of(rhp, struct task_group, rcu)); +} + +static void sched_unregister_group(struct task_group *tg) +{ + /* + * We have to wait for yet another RCU grace period to expire, as + * print_cfs_stats() might run concurrently. + */ + call_rcu(&tg->rcu, sched_free_group_rcu); +} + +/* allocate runqueue etc for a new task group */ +struct task_group *sched_create_group(struct task_group *parent) +{ + struct task_group *tg; + + tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); + if (!tg) + return ERR_PTR(-ENOMEM); + + return tg; +} + +void sched_online_group(struct task_group *tg, struct task_group *parent) +{ +} + +/* RCU callback to free various structures associated with a task group */ +static void sched_unregister_group_rcu(struct rcu_head *rhp) +{ + /* Now it should be safe to free those cfs_rqs: */ + sched_unregister_group(container_of(rhp, struct task_group, rcu)); +} + +void sched_destroy_group(struct task_group *tg) +{ + /* Wait for possible concurrent references to cfs_rqs complete: */ + call_rcu(&tg->rcu, sched_unregister_group_rcu); +} + +void sched_release_group(struct task_group *tg) +{ +} + +static inline struct task_group *css_tg(struct cgroup_subsys_state *css) +{ + return css ? container_of(css, struct task_group, css) : NULL; +} + +static struct cgroup_subsys_state * +cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) +{ + struct task_group *parent = css_tg(parent_css); + struct task_group *tg; + + if (!parent) { + /* This is early initialization for the top cgroup */ + return &root_task_group.css; + } + + tg = sched_create_group(parent); + if (IS_ERR(tg)) + return ERR_PTR(-ENOMEM); + return &tg->css; +} + +/* Expose task group only after completing cgroup initialization */ +static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) +{ + struct task_group *tg = css_tg(css); + struct task_group *parent = css_tg(css->parent); + + if (parent) + sched_online_group(tg, parent); + return 0; +} + +static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) +{ + struct task_group *tg = css_tg(css); + + sched_release_group(tg); +} + +static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) +{ + struct task_group *tg = css_tg(css); + + /* + * Relies on the RCU grace period between css_released() and this. + */ + sched_unregister_group(tg); +} + +#ifdef CONFIG_RT_GROUP_SCHED +static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) +{ + return 0; +} +#endif + +static void cpu_cgroup_attach(struct cgroup_taskset *tset) +{ +} + +#ifdef CONFIG_GROUP_SCHED_WEIGHT +static int sched_group_set_shares(struct task_group *tg, unsigned long shares) +{ + return 0; +} + +static int sched_group_set_idle(struct task_group *tg, long idle) +{ + return 0; +} + +static int cpu_shares_write_u64(struct cgroup_subsys_state *css, + struct cftype *cftype, u64 shareval) +{ + return sched_group_set_shares(css_tg(css), shareval); +} + +static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static s64 cpu_idle_read_s64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_idle_write_s64(struct cgroup_subsys_state *css, + struct cftype *cft, s64 idle) +{ + return sched_group_set_idle(css_tg(css), idle); +} +#endif + +#ifdef CONFIG_CFS_BANDWIDTH +static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, + struct cftype *cftype, s64 cfs_quota_us) +{ + return 0; +} + +static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, + struct cftype *cftype, u64 cfs_period_us) +{ + return 0; +} + +static u64 cpu_cfs_burst_read_u64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_cfs_burst_write_u64(struct cgroup_subsys_state *css, + struct cftype *cftype, u64 cfs_burst_us) +{ + return 0; +} + +static int cpu_cfs_stat_show(struct seq_file *sf, void *v) +{ + return 0; +} + +static int cpu_cfs_local_stat_show(struct seq_file *sf, void *v) +{ + return 0; +} +#endif + +#ifdef CONFIG_RT_GROUP_SCHED +static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, + struct cftype *cft, s64 val) +{ + return 0; +} + +static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, + struct cftype *cftype, u64 rt_period_us) +{ + return 0; +} + +static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} +#endif + +#ifdef CONFIG_UCLAMP_TASK_GROUP +static int cpu_uclamp_min_show(struct seq_file *sf, void *v) +{ + return 0; +} + +static int cpu_uclamp_max_show(struct seq_file *sf, void *v) +{ + return 0; +} + +static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, + loff_t off) +{ + return nbytes; +} + +static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, + loff_t off) +{ + return nbytes; +} +#endif + +static struct cftype cpu_legacy_files[] = { +#ifdef CONFIG_GROUP_SCHED_WEIGHT + { + .name = "shares", + .read_u64 = cpu_shares_read_u64, + .write_u64 = cpu_shares_write_u64, + }, + { + .name = "idle", + .read_s64 = cpu_idle_read_s64, + .write_s64 = cpu_idle_write_s64, + }, +#endif +#ifdef CONFIG_CFS_BANDWIDTH + { + .name = "cfs_quota_us", + .read_s64 = cpu_cfs_quota_read_s64, + .write_s64 = cpu_cfs_quota_write_s64, + }, + { + .name = "cfs_period_us", + .read_u64 = cpu_cfs_period_read_u64, + .write_u64 = cpu_cfs_period_write_u64, + }, + { + .name = "cfs_burst_us", + .read_u64 = cpu_cfs_burst_read_u64, + .write_u64 = cpu_cfs_burst_write_u64, + }, + { + .name = "stat", + .seq_show = cpu_cfs_stat_show, + }, + { + .name = "stat.local", + .seq_show = cpu_cfs_local_stat_show, + }, +#endif +#ifdef CONFIG_RT_GROUP_SCHED + { + .name = "rt_runtime_us", + .read_s64 = cpu_rt_runtime_read, + .write_s64 = cpu_rt_runtime_write, + }, + { + .name = "rt_period_us", + .read_u64 = cpu_rt_period_read_uint, + .write_u64 = cpu_rt_period_write_uint, + }, +#endif +#ifdef CONFIG_UCLAMP_TASK_GROUP + { + .name = "uclamp.min", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cpu_uclamp_min_show, + .write = cpu_uclamp_min_write, + }, + { + .name = "uclamp.max", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cpu_uclamp_max_show, + .write = cpu_uclamp_max_write, + }, +#endif + { } /* Terminate */ +}; + +#ifdef CONFIG_GROUP_SCHED_WEIGHT +static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_weight_write_u64(struct cgroup_subsys_state *css, + struct cftype *cft, u64 weight) +{ + return 0; +} + +static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return 0; +} + +static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css, + struct cftype *cft, s64 nice) +{ + return 0; +} +#endif + +#ifdef CONFIG_CFS_BANDWIDTH +static int cpu_max_show(struct seq_file *sf, void *v) +{ + return 0; +} + +static ssize_t cpu_max_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + return nbytes; +} +#endif + +static struct cftype cpu_files[] = { +#ifdef CONFIG_GROUP_SCHED_WEIGHT + { + .name = "weight", + .flags = CFTYPE_NOT_ON_ROOT, + .read_u64 = cpu_weight_read_u64, + .write_u64 = cpu_weight_write_u64, + }, + { + .name = "weight.nice", + .flags = CFTYPE_NOT_ON_ROOT, + .read_s64 = cpu_weight_nice_read_s64, + .write_s64 = cpu_weight_nice_write_s64, + }, + { + .name = "idle", + .flags = CFTYPE_NOT_ON_ROOT, + .read_s64 = cpu_idle_read_s64, + .write_s64 = cpu_idle_write_s64, + }, +#endif +#ifdef CONFIG_CFS_BANDWIDTH + { + .name = "max", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cpu_max_show, + .write = cpu_max_write, + }, + { + .name = "max.burst", + .flags = CFTYPE_NOT_ON_ROOT, + .read_u64 = cpu_cfs_burst_read_u64, + .write_u64 = cpu_cfs_burst_write_u64, + }, +#endif +#ifdef CONFIG_UCLAMP_TASK_GROUP + { + .name = "uclamp.min", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cpu_uclamp_min_show, + .write = cpu_uclamp_min_write, + }, + { + .name = "uclamp.max", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cpu_uclamp_max_show, + .write = cpu_uclamp_max_write, + }, +#endif + { } /* terminate */ +}; + +static int cpu_extra_stat_show(struct seq_file *sf, + struct cgroup_subsys_state *css) +{ + return 0; +} + +static int cpu_local_stat_show(struct seq_file *sf, + struct cgroup_subsys_state *css) +{ + return 0; +} + +struct cgroup_subsys cpu_cgrp_subsys = { + .css_alloc = cpu_cgroup_css_alloc, + .css_online = cpu_cgroup_css_online, + .css_released = cpu_cgroup_css_released, + .css_free = cpu_cgroup_css_free, + .css_extra_stat_show = cpu_extra_stat_show, + .css_local_stat_show = cpu_local_stat_show, +#ifdef CONFIG_RT_GROUP_SCHED + .can_attach = cpu_cgroup_can_attach, +#endif + .attach = cpu_cgroup_attach, + .legacy_cftypes = cpu_legacy_files, + .dfl_cftypes = cpu_files, + .early_init = true, + .threaded = true, +}; +#endif /* CONFIG_CGROUP_SCHED */ + +#undef CREATE_TRACE_POINTS + +#ifdef CONFIG_SCHED_MM_CID + +# +/* + * @cid_lock: Guarantee forward-progress of cid allocation. + * + * Concurrency ID allocation within a bitmap is mostly lock-free. The cid_lock + * is only used when contention is detected by the lock-free allocation so + * forward progress can be guaranteed. + */ +DEFINE_RAW_SPINLOCK(cid_lock); + +/* + * @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock. + * + * When @use_cid_lock is 0, the cid allocation is lock-free. When contention is + * detected, it is set to 1 to ensure that all newly coming allocations are + * serialized by @cid_lock until the allocation which detected contention + * completes and sets @use_cid_lock back to 0. This guarantees forward progress + * of a cid allocation. + */ +int use_cid_lock; + +/* + * mm_cid remote-clear implements a lock-free algorithm to clear per-mm/cpu cid + * concurrently with respect to the execution of the source runqueue context + * switch. + * + * There is one basic properties we want to guarantee here: + * + * (1) Remote-clear should _never_ mark a per-cpu cid UNSET when it is actively + * used by a task. That would lead to concurrent allocation of the cid and + * userspace corruption. + * + * Provide this guarantee by introducing a Dekker memory ordering to guarantee + * that a pair of loads observe at least one of a pair of stores, which can be + * shown as: + * + * X = Y = 0 + * + * w[X]=1 w[Y]=1 + * MB MB + * r[Y]=y r[X]=x + * + * Which guarantees that x==0 && y==0 is impossible. But rather than using + * values 0 and 1, this algorithm cares about specific state transitions of the + * runqueue current task (as updated by the scheduler context switch), and the + * per-mm/cpu cid value. + * + * Let's introduce task (Y) which has task->mm == mm and task (N) which has + * task->mm != mm for the rest of the discussion. There are two scheduler state + * transitions on context switch we care about: + * + * (TSA) Store to rq->curr with transition from (N) to (Y) + * + * (TSB) Store to rq->curr with transition from (Y) to (N) + * + * On the remote-clear side, there is one transition we care about: + * + * (TMA) cmpxchg to *pcpu_cid to set the LAZY flag + * + * There is also a transition to UNSET state which can be performed from all + * sides (scheduler, remote-clear). It is always performed with a cmpxchg which + * guarantees that only a single thread will succeed: + * + * (TMB) cmpxchg to *pcpu_cid to mark UNSET + * + * Just to be clear, what we do _not_ want to happen is a transition to UNSET + * when a thread is actively using the cid (property (1)). + * + * Let's looks at the relevant combinations of TSA/TSB, and TMA transitions. + * + * Scenario A) (TSA)+(TMA) (from next task perspective) + * + * CPU0 CPU1 + * + * Context switch CS-1 Remote-clear + * - store to rq->curr: (N)->(Y) (TSA) - cmpxchg to *pcpu_id to LAZY (TMA) + * (implied barrier after cmpxchg) + * - switch_mm_cid() + * - memory barrier (see switch_mm_cid() + * comment explaining how this barrier + * is combined with other scheduler + * barriers) + * - mm_cid_get (next) + * - READ_ONCE(*pcpu_cid) - rcu_dereference(src_rq->curr) + * + * This Dekker ensures that either task (Y) is observed by the + * rcu_dereference() or the LAZY flag is observed by READ_ONCE(), or both are + * observed. + * + * If task (Y) store is observed by rcu_dereference(), it means that there is + * still an active task on the cpu. Remote-clear will therefore not transition + * to UNSET, which fulfills property (1). + * + * If task (Y) is not observed, but the lazy flag is observed by READ_ONCE(), + * it will move its state to UNSET, which clears the percpu cid perhaps + * uselessly (which is not an issue for correctness). Because task (Y) is not + * observed, CPU1 can move ahead to set the state to UNSET. Because moving + * state to UNSET is done with a cmpxchg expecting that the old state has the + * LAZY flag set, only one thread will successfully UNSET. + * + * If both states (LAZY flag and task (Y)) are observed, the thread on CPU0 + * will observe the LAZY flag and transition to UNSET (perhaps uselessly), and + * CPU1 will observe task (Y) and do nothing more, which is fine. + * + * What we are effectively preventing with this Dekker is a scenario where + * neither LAZY flag nor store (Y) are observed, which would fail property (1) + * because this would UNSET a cid which is actively used. + */ + +void sched_mm_cid_migrate_from(struct task_struct *t) +{ + t->migrate_from_cpu = task_cpu(t); +} + +static +int __sched_mm_cid_migrate_from_fetch_cid(struct rq *src_rq, + struct task_struct *t, + struct mm_cid *src_pcpu_cid) +{ + struct mm_struct *mm = t->mm; + struct task_struct *src_task; + int src_cid, last_mm_cid; + + if (!mm) + return -1; + + last_mm_cid = t->last_mm_cid; + /* + * If the migrated task has no last cid, or if the current + * task on src rq uses the cid, it means the source cid does not need + * to be moved to the destination cpu. + */ + if (last_mm_cid == -1) + return -1; + src_cid = READ_ONCE(src_pcpu_cid->cid); + if (!mm_cid_is_valid(src_cid) || last_mm_cid != src_cid) + return -1; + + /* + * If we observe an active task using the mm on this rq, it means we + * are not the last task to be migrated from this cpu for this mm, so + * there is no need to move src_cid to the destination cpu. + */ + guard(rcu)(); + src_task = rcu_dereference(src_rq->curr); + if (READ_ONCE(src_task->mm_cid_active) && src_task->mm == mm) { + t->last_mm_cid = -1; + return -1; + } + + return src_cid; +} + +static +int __sched_mm_cid_migrate_from_try_steal_cid(struct rq *src_rq, + struct task_struct *t, + struct mm_cid *src_pcpu_cid, + int src_cid) +{ + struct task_struct *src_task; + struct mm_struct *mm = t->mm; + int lazy_cid; + + if (src_cid == -1) + return -1; + + /* + * Attempt to clear the source cpu cid to move it to the destination + * cpu. + */ + lazy_cid = mm_cid_set_lazy_put(src_cid); + if (!try_cmpxchg(&src_pcpu_cid->cid, &src_cid, lazy_cid)) + return -1; + + /* + * The implicit barrier after cmpxchg per-mm/cpu cid before loading + * rq->curr->mm matches the scheduler barrier in context_switch() + * between store to rq->curr and load of prev and next task's + * per-mm/cpu cid. + * + * The implicit barrier after cmpxchg per-mm/cpu cid before loading + * rq->curr->mm_cid_active matches the barrier in + * sched_mm_cid_exit_signals(), sched_mm_cid_before_execve(), and + * sched_mm_cid_after_execve() between store to t->mm_cid_active and + * load of per-mm/cpu cid. + */ + + /* + * If we observe an active task using the mm on this rq after setting + * the lazy-put flag, this task will be responsible for transitioning + * from lazy-put flag set to MM_CID_UNSET. + */ + scoped_guard (rcu) { + src_task = rcu_dereference(src_rq->curr); + if (READ_ONCE(src_task->mm_cid_active) && src_task->mm == mm) { + rcu_read_unlock(); + /* + * We observed an active task for this mm, there is therefore + * no point in moving this cid to the destination cpu. + */ + t->last_mm_cid = -1; + return -1; + } + } + + /* + * The src_cid is unused, so it can be unset. + */ + if (!try_cmpxchg(&src_pcpu_cid->cid, &lazy_cid, MM_CID_UNSET)) + return -1; + WRITE_ONCE(src_pcpu_cid->recent_cid, MM_CID_UNSET); + return src_cid; +} + +/* + * Migration to dst cpu. Called with dst_rq lock held. + * Interrupts are disabled, which keeps the window of cid ownership without the + * source rq lock held small. + */ +void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t) +{ + struct mm_cid *src_pcpu_cid, *dst_pcpu_cid; + struct mm_struct *mm = t->mm; + int src_cid, src_cpu; + bool dst_cid_is_set; + struct rq *src_rq; + + lockdep_assert_rq_held(dst_rq); + + if (!mm) + return; + src_cpu = t->migrate_from_cpu; + if (src_cpu == -1) { + t->last_mm_cid = -1; + return; + } + /* + * Move the src cid if the dst cid is unset. This keeps id + * allocation closest to 0 in cases where few threads migrate around + * many CPUs. + * + * If destination cid or recent cid is already set, we may have + * to just clear the src cid to ensure compactness in frequent + * migrations scenarios. + * + * It is not useful to clear the src cid when the number of threads is + * greater or equal to the number of allowed CPUs, because user-space + * can expect that the number of allowed cids can reach the number of + * allowed CPUs. + */ + dst_pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu_of(dst_rq)); + dst_cid_is_set = !mm_cid_is_unset(READ_ONCE(dst_pcpu_cid->cid)) || + !mm_cid_is_unset(READ_ONCE(dst_pcpu_cid->recent_cid)); + if (dst_cid_is_set && atomic_read(&mm->mm_users) >= READ_ONCE(mm->nr_cpus_allowed)) + return; + src_pcpu_cid = per_cpu_ptr(mm->pcpu_cid, src_cpu); + src_rq = cpu_rq(src_cpu); + src_cid = __sched_mm_cid_migrate_from_fetch_cid(src_rq, t, src_pcpu_cid); + if (src_cid == -1) + return; + src_cid = __sched_mm_cid_migrate_from_try_steal_cid(src_rq, t, src_pcpu_cid, + src_cid); + if (src_cid == -1) + return; + if (dst_cid_is_set) { + __mm_cid_put(mm, src_cid); + return; + } + /* Move src_cid to dst cpu. */ + mm_cid_snapshot_time(dst_rq, mm); + WRITE_ONCE(dst_pcpu_cid->cid, src_cid); + WRITE_ONCE(dst_pcpu_cid->recent_cid, src_cid); +} + +static void sched_mm_cid_remote_clear(struct mm_struct *mm, struct mm_cid *pcpu_cid, + int cpu) +{ + struct rq *rq = cpu_rq(cpu); + struct task_struct *t; + int cid, lazy_cid; + + cid = READ_ONCE(pcpu_cid->cid); + if (!mm_cid_is_valid(cid)) + return; + + /* + * Clear the cpu cid if it is set to keep cid allocation compact. If + * there happens to be other tasks left on the source cpu using this + * mm, the next task using this mm will reallocate its cid on context + * switch. + */ + lazy_cid = mm_cid_set_lazy_put(cid); + if (!try_cmpxchg(&pcpu_cid->cid, &cid, lazy_cid)) + return; + + /* + * The implicit barrier after cmpxchg per-mm/cpu cid before loading + * rq->curr->mm matches the scheduler barrier in context_switch() + * between store to rq->curr and load of prev and next task's + * per-mm/cpu cid. + * + * The implicit barrier after cmpxchg per-mm/cpu cid before loading + * rq->curr->mm_cid_active matches the barrier in + * sched_mm_cid_exit_signals(), sched_mm_cid_before_execve(), and + * sched_mm_cid_after_execve() between store to t->mm_cid_active and + * load of per-mm/cpu cid. + */ + + /* + * If we observe an active task using the mm on this rq after setting + * the lazy-put flag, that task will be responsible for transitioning + * from lazy-put flag set to MM_CID_UNSET. + */ + scoped_guard (rcu) { + t = rcu_dereference(rq->curr); + if (READ_ONCE(t->mm_cid_active) && t->mm == mm) + return; + } + + /* + * The cid is unused, so it can be unset. + * Disable interrupts to keep the window of cid ownership without rq + * lock small. + */ + scoped_guard (irqsave) { + if (try_cmpxchg(&pcpu_cid->cid, &lazy_cid, MM_CID_UNSET)) + __mm_cid_put(mm, cid); + } +} + +static void sched_mm_cid_remote_clear_old(struct mm_struct *mm, int cpu) +{ + struct rq *rq = cpu_rq(cpu); + struct mm_cid *pcpu_cid; + struct task_struct *curr; + u64 rq_clock; + + /* + * rq->clock load is racy on 32-bit but one spurious clear once in a + * while is irrelevant. + */ + rq_clock = READ_ONCE(rq->clock); + pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu); + + /* + * In order to take care of infrequently scheduled tasks, bump the time + * snapshot associated with this cid if an active task using the mm is + * observed on this rq. + */ + scoped_guard (rcu) { + curr = rcu_dereference(rq->curr); + if (READ_ONCE(curr->mm_cid_active) && curr->mm == mm) { + WRITE_ONCE(pcpu_cid->time, rq_clock); + return; + } + } + + if (rq_clock < pcpu_cid->time + SCHED_MM_CID_PERIOD_NS) + return; + sched_mm_cid_remote_clear(mm, pcpu_cid, cpu); +} + +static void sched_mm_cid_remote_clear_weight(struct mm_struct *mm, int cpu, + int weight) +{ + struct mm_cid *pcpu_cid; + int cid; + + pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu); + cid = READ_ONCE(pcpu_cid->cid); + if (!mm_cid_is_valid(cid) || cid < weight) + return; + sched_mm_cid_remote_clear(mm, pcpu_cid, cpu); +} + +static void task_mm_cid_work(struct callback_head *work) +{ + unsigned long now = jiffies, old_scan, next_scan; + struct task_struct *t = current; + struct cpumask *cidmask; + struct mm_struct *mm; + int weight, cpu; + + SCHED_WARN_ON(t != container_of(work, struct task_struct, cid_work)); + + work->next = work; /* Prevent double-add */ + if (t->flags & PF_EXITING) + return; + mm = t->mm; + if (!mm) + return; + old_scan = READ_ONCE(mm->mm_cid_next_scan); + next_scan = now + msecs_to_jiffies(MM_CID_SCAN_DELAY); + if (!old_scan) { + unsigned long res; + + res = cmpxchg(&mm->mm_cid_next_scan, old_scan, next_scan); + if (res != old_scan) + old_scan = res; + else + old_scan = next_scan; + } + if (time_before(now, old_scan)) + return; + if (!try_cmpxchg(&mm->mm_cid_next_scan, &old_scan, next_scan)) + return; + cidmask = mm_cidmask(mm); + /* Clear cids that were not recently used. */ + for_each_possible_cpu(cpu) + sched_mm_cid_remote_clear_old(mm, cpu); + weight = cpumask_weight(cidmask); + /* + * Clear cids that are greater or equal to the cidmask weight to + * recompact it. + */ + for_each_possible_cpu(cpu) + sched_mm_cid_remote_clear_weight(mm, cpu, weight); +} + +void init_sched_mm_cid(struct task_struct *t) +{ + struct mm_struct *mm = t->mm; + int mm_users = 0; + + if (mm) { + mm_users = atomic_read(&mm->mm_users); + if (mm_users == 1) + mm->mm_cid_next_scan = jiffies + msecs_to_jiffies(MM_CID_SCAN_DELAY); + } + t->cid_work.next = &t->cid_work; /* Protect against double add */ + init_task_work(&t->cid_work, task_mm_cid_work); +} + +void task_tick_mm_cid(struct rq *rq, struct task_struct *curr) +{ + struct callback_head *work = &curr->cid_work; + unsigned long now = jiffies; + + if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || + work->next != work) + return; + if (time_before(now, READ_ONCE(curr->mm->mm_cid_next_scan))) + return; + + /* No page allocation under rq lock */ + task_work_add(curr, work, TWA_RESUME | TWAF_NO_ALLOC); +} + +void sched_mm_cid_exit_signals(struct task_struct *t) +{ + struct mm_struct *mm = t->mm; + struct rq *rq; + + if (!mm) + return; + + preempt_disable(); + rq = this_rq(); + guard(rq_lock_irqsave)(rq); + preempt_enable_no_resched(); /* holding spinlock */ + WRITE_ONCE(t->mm_cid_active, 0); + /* + * Store t->mm_cid_active before loading per-mm/cpu cid. + * Matches barrier in sched_mm_cid_remote_clear_old(). + */ + smp_mb(); + mm_cid_put(mm); + t->last_mm_cid = t->mm_cid = -1; +} + +void sched_mm_cid_before_execve(struct task_struct *t) +{ + struct mm_struct *mm = t->mm; + struct rq *rq; + + if (!mm) + return; + + preempt_disable(); + rq = this_rq(); + guard(rq_lock_irqsave)(rq); + preempt_enable_no_resched(); /* holding spinlock */ + WRITE_ONCE(t->mm_cid_active, 0); + /* + * Store t->mm_cid_active before loading per-mm/cpu cid. + * Matches barrier in sched_mm_cid_remote_clear_old(). + */ + smp_mb(); + mm_cid_put(mm); + t->last_mm_cid = t->mm_cid = -1; +} + +void sched_mm_cid_after_execve(struct task_struct *t) +{ + struct mm_struct *mm = t->mm; + struct rq *rq; + + if (!mm) + return; + + preempt_disable(); + rq = this_rq(); + scoped_guard (rq_lock_irqsave, rq) { + preempt_enable_no_resched(); /* holding spinlock */ + WRITE_ONCE(t->mm_cid_active, 1); + /* + * Store t->mm_cid_active before loading per-mm/cpu cid. + * Matches barrier in sched_mm_cid_remote_clear_old(). + */ + smp_mb(); + t->last_mm_cid = t->mm_cid = mm_cid_get(rq, t, mm); + } + rseq_set_notify_resume(t); +} + +void sched_mm_cid_fork(struct task_struct *t) +{ + WARN_ON_ONCE(!t->mm || t->mm_cid != -1); + t->mm_cid_active = 1; +} +#endif diff --git a/kernel/sched/alt_core.h b/kernel/sched/alt_core.h new file mode 100644 index 000000000..12d76d9d2 --- /dev/null +++ b/kernel/sched/alt_core.h @@ -0,0 +1,213 @@ +#ifndef _KERNEL_SCHED_ALT_CORE_H +#define _KERNEL_SCHED_ALT_CORE_H + +/* + * Compile time debug macro + * #define ALT_SCHED_DEBUG + */ + +/* + * Task related inlined functions + */ +static inline bool is_migration_disabled(struct task_struct *p) +{ +#ifdef CONFIG_SMP + return p->migration_disabled; +#else + return false; +#endif +} + +/* rt_prio(prio) defined in include/linux/sched/rt.h */ +#define rt_task(p) rt_prio((p)->prio) +#define rt_policy(policy) ((policy) == SCHED_FIFO || (policy) == SCHED_RR) +#define task_has_rt_policy(p) (rt_policy((p)->policy)) + +struct affinity_context { + const struct cpumask *new_mask; + struct cpumask *user_mask; + unsigned int flags; +}; + +/* CONFIG_SCHED_CLASS_EXT is not supported */ +#define scx_switched_all() false + +#define SCA_CHECK 0x01 +#define SCA_MIGRATE_DISABLE 0x02 +#define SCA_MIGRATE_ENABLE 0x04 +#define SCA_USER 0x08 + +#ifdef CONFIG_SMP + +extern int __set_cpus_allowed_ptr(struct task_struct *p, struct affinity_context *ctx); + +static inline cpumask_t *alloc_user_cpus_ptr(int node) +{ + /* + * See do_set_cpus_allowed() above for the rcu_head usage. + */ + int size = max_t(int, cpumask_size(), sizeof(struct rcu_head)); + + return kmalloc_node(size, GFP_KERNEL, node); +} + +#else /* !CONFIG_SMP: */ + +static inline int __set_cpus_allowed_ptr(struct task_struct *p, + struct affinity_context *ctx) +{ + return set_cpus_allowed_ptr(p, ctx->new_mask); +} + +static inline cpumask_t *alloc_user_cpus_ptr(int node) +{ + return NULL; +} + +#endif /* !CONFIG_SMP */ + +#ifdef CONFIG_RT_MUTEXES + +static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) +{ + if (pi_task) + prio = min(prio, pi_task->prio); + + return prio; +} + +static inline int rt_effective_prio(struct task_struct *p, int prio) +{ + struct task_struct *pi_task = rt_mutex_get_top_task(p); + + return __rt_effective_prio(pi_task, prio); +} + +#else /* !CONFIG_RT_MUTEXES: */ + +static inline int rt_effective_prio(struct task_struct *p, int prio) +{ + return prio; +} + +#endif /* !CONFIG_RT_MUTEXES */ + +extern int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user, bool pi); +extern int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx); +extern void __setscheduler_prio(struct task_struct *p, int prio); + +/* + * Context API + */ +static inline struct rq *__task_access_lock(struct task_struct *p, raw_spinlock_t **plock) +{ + struct rq *rq; + for (;;) { + rq = task_rq(p); + if (p->on_cpu || task_on_rq_queued(p)) { + raw_spin_lock(&rq->lock); + if (likely((p->on_cpu || task_on_rq_queued(p)) && rq == task_rq(p))) { + *plock = &rq->lock; + return rq; + } + raw_spin_unlock(&rq->lock); + } else if (task_on_rq_migrating(p)) { + do { + cpu_relax(); + } while (unlikely(task_on_rq_migrating(p))); + } else { + *plock = NULL; + return rq; + } + } +} + +static inline void __task_access_unlock(struct task_struct *p, raw_spinlock_t *lock) +{ + if (NULL != lock) + raw_spin_unlock(lock); +} + +void check_task_changed(struct task_struct *p, struct rq *rq); + +/* + * RQ related inlined functions + */ + +/* + * This routine assume that the idle task always in queue + */ +static inline struct task_struct *sched_rq_first_task(struct rq *rq) +{ + const struct list_head *head = &rq->queue.heads[sched_rq_prio_idx(rq)]; + + return list_first_entry(head, struct task_struct, sq_node); +} + +static inline struct task_struct * sched_rq_next_task(struct task_struct *p, struct rq *rq) +{ + struct list_head *next = p->sq_node.next; + + if (&rq->queue.heads[0] <= next && next < &rq->queue.heads[SCHED_LEVELS]) { + struct list_head *head; + unsigned long idx = next - &rq->queue.heads[0]; + + idx = find_next_bit(rq->queue.bitmap, SCHED_QUEUE_BITS, + sched_idx2prio(idx, rq) + 1); + head = &rq->queue.heads[sched_prio2idx(idx, rq)]; + + return list_first_entry(head, struct task_struct, sq_node); + } + + return list_next_entry(p, sq_node); +} + +extern void requeue_task(struct task_struct *p, struct rq *rq); + +#ifdef ALT_SCHED_DEBUG +extern void alt_sched_debug(void); +#else +static inline void alt_sched_debug(void) {} +#endif + +extern int sched_yield_type; + +#ifdef CONFIG_SMP +extern cpumask_t sched_rq_pending_mask ____cacheline_aligned_in_smp; + +DECLARE_STATIC_KEY_FALSE(sched_smt_present); +DECLARE_PER_CPU_ALIGNED(cpumask_t *, sched_cpu_llc_mask); + +extern cpumask_t sched_smt_mask ____cacheline_aligned_in_smp; + +extern cpumask_t *const sched_idle_mask; +extern cpumask_t *const sched_sg_idle_mask; +extern cpumask_t *const sched_pcore_idle_mask; +extern cpumask_t *const sched_ecore_idle_mask; + +extern struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu); + +typedef bool (*idle_select_func_t)(struct cpumask *dstp, const struct cpumask *src1p, + const struct cpumask *src2p); + +extern idle_select_func_t idle_select_func; +#endif + +/* balance callback */ +#ifdef CONFIG_SMP +extern struct balance_callback *splice_balance_callbacks(struct rq *rq); +extern void balance_callbacks(struct rq *rq, struct balance_callback *head); +#else + +static inline struct balance_callback *splice_balance_callbacks(struct rq *rq) +{ + return NULL; +} + +static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) +{ +} + +#endif + +#endif /* _KERNEL_SCHED_ALT_CORE_H */ diff --git a/kernel/sched/alt_debug.c b/kernel/sched/alt_debug.c new file mode 100644 index 000000000..1dbd7eb6a --- /dev/null +++ b/kernel/sched/alt_debug.c @@ -0,0 +1,32 @@ +/* + * kernel/sched/alt_debug.c + * + * Print the alt scheduler debugging details + * + * Author: Alfred Chen + * Date : 2020 + */ +#include "sched.h" +#include "linux/sched/debug.h" + +/* + * This allows printing both to /proc/sched_debug and + * to the console + */ +#define SEQ_printf(m, x...) \ + do { \ + if (m) \ + seq_printf(m, x); \ + else \ + pr_cont(x); \ + } while (0) + +void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns, + struct seq_file *m) +{ + SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, task_pid_nr_ns(p, ns), + get_nr_threads(p)); +} + +void proc_sched_set_task(struct task_struct *p) +{} diff --git a/kernel/sched/alt_sched.h b/kernel/sched/alt_sched.h new file mode 100644 index 000000000..7a2def094 --- /dev/null +++ b/kernel/sched/alt_sched.h @@ -0,0 +1,1019 @@ +#ifndef _KERNEL_SCHED_ALT_SCHED_H +#define _KERNEL_SCHED_ALT_SCHED_H + +#include +#include +#include +#include +#include + +#include +#include + +#include "../workqueue_internal.h" + +#include "cpupri.h" + +#ifdef CONFIG_CGROUP_SCHED +/* task group related information */ +struct task_group { + struct cgroup_subsys_state css; + + struct rcu_head rcu; + struct list_head list; + + struct task_group *parent; + struct list_head siblings; + struct list_head children; +}; + +extern struct task_group *sched_create_group(struct task_group *parent); +extern void sched_online_group(struct task_group *tg, + struct task_group *parent); +extern void sched_destroy_group(struct task_group *tg); +extern void sched_release_group(struct task_group *tg); +#endif /* CONFIG_CGROUP_SCHED */ + +#define MIN_SCHED_NORMAL_PRIO (32) +/* + * levels: RT(0-24), reserved(25-31), NORMAL(32-63), cpu idle task(64) + * + * -- BMQ -- + * NORMAL: (lower boost range 12, NICE_WIDTH 40, higher boost range 12) / 2 + * -- PDS -- + * NORMAL: SCHED_EDGE_DELTA + ((NICE_WIDTH 40) / 2) + */ +#define SCHED_LEVELS (64 + 1) + +#define IDLE_TASK_SCHED_PRIO (SCHED_LEVELS - 1) + +#ifdef CONFIG_SCHED_DEBUG +# define SCHED_WARN_ON(x) WARN_ONCE(x, #x) +extern void resched_latency_warn(int cpu, u64 latency); +#else +# define SCHED_WARN_ON(x) ({ (void)(x), 0; }) +static inline void resched_latency_warn(int cpu, u64 latency) {} +#endif + +/* + * Increase resolution of nice-level calculations for 64-bit architectures. + * The extra resolution improves shares distribution and load balancing of + * low-weight task groups (eg. nice +19 on an autogroup), deeper taskgroup + * hierarchies, especially on larger systems. This is not a user-visible change + * and does not change the user-interface for setting shares/weights. + * + * We increase resolution only if we have enough bits to allow this increased + * resolution (i.e. 64-bit). The costs for increasing resolution when 32-bit + * are pretty high and the returns do not justify the increased costs. + * + * Really only required when CONFIG_FAIR_GROUP_SCHED=y is also set, but to + * increase coverage and consistency always enable it on 64-bit platforms. + */ +#ifdef CONFIG_64BIT +# define NICE_0_LOAD_SHIFT (SCHED_FIXEDPOINT_SHIFT + SCHED_FIXEDPOINT_SHIFT) +# define scale_load(w) ((w) << SCHED_FIXEDPOINT_SHIFT) +# define scale_load_down(w) \ +({ \ + unsigned long __w = (w); \ + if (__w) \ + __w = max(2UL, __w >> SCHED_FIXEDPOINT_SHIFT); \ + __w; \ +}) +#else +# define NICE_0_LOAD_SHIFT (SCHED_FIXEDPOINT_SHIFT) +# define scale_load(w) (w) +# define scale_load_down(w) (w) +#endif + +/* + * Tunables that become constants when CONFIG_SCHED_DEBUG is off: + */ +#ifdef CONFIG_SCHED_DEBUG +# define const_debug __read_mostly +#else +# define const_debug const +#endif + +/* task_struct::on_rq states: */ +#define TASK_ON_RQ_QUEUED 1 +#define TASK_ON_RQ_MIGRATING 2 + +static inline int task_on_rq_queued(struct task_struct *p) +{ + return p->on_rq == TASK_ON_RQ_QUEUED; +} + +static inline int task_on_rq_migrating(struct task_struct *p) +{ + return READ_ONCE(p->on_rq) == TASK_ON_RQ_MIGRATING; +} + +/* Wake flags. The first three directly map to some SD flag value */ +#define WF_EXEC 0x02 /* Wakeup after exec; maps to SD_BALANCE_EXEC */ +#define WF_FORK 0x04 /* Wakeup after fork; maps to SD_BALANCE_FORK */ +#define WF_TTWU 0x08 /* Wakeup; maps to SD_BALANCE_WAKE */ + +#define WF_SYNC 0x10 /* Waker goes to sleep after wakeup */ +#define WF_MIGRATED 0x20 /* Internal use, task got migrated */ +#define WF_CURRENT_CPU 0x40 /* Prefer to move the wakee to the current CPU. */ + +#ifdef CONFIG_SMP +static_assert(WF_EXEC == SD_BALANCE_EXEC); +static_assert(WF_FORK == SD_BALANCE_FORK); +static_assert(WF_TTWU == SD_BALANCE_WAKE); +#endif + +#define SCHED_QUEUE_BITS (SCHED_LEVELS - 1) + +struct sched_queue { + DECLARE_BITMAP(bitmap, SCHED_QUEUE_BITS); + struct list_head heads[SCHED_LEVELS]; +}; + +struct rq; +struct cpuidle_state; + +struct balance_callback { + struct balance_callback *next; + void (*func)(struct rq *rq); +}; + +typedef void (*balance_func_t)(struct rq *rq, int cpu); +typedef void (*set_idle_mask_func_t)(unsigned int cpu, struct cpumask *dstp); +typedef void (*clear_idle_mask_func_t)(int cpu, struct cpumask *dstp); + +struct balance_arg { + struct task_struct *task; + int active; + cpumask_t *cpumask; +}; + +/* + * This is the main, per-CPU runqueue data structure. + * This data should only be modified by the local cpu. + */ +struct rq { + /* runqueue lock: */ + raw_spinlock_t lock; + + struct task_struct __rcu *curr; + struct task_struct *idle; + struct task_struct *stop; + struct mm_struct *prev_mm; + + struct sched_queue queue ____cacheline_aligned; + + int prio; +#ifdef CONFIG_SCHED_PDS + int prio_idx; + u64 time_edge; +#endif + + /* switch count */ + u64 nr_switches; + + atomic_t nr_iowait; + +#ifdef CONFIG_SCHED_DEBUG + u64 last_seen_need_resched_ns; + int ticks_without_resched; +#endif + +#ifdef CONFIG_MEMBARRIER + int membarrier_state; +#endif + + set_idle_mask_func_t set_idle_mask_func; + clear_idle_mask_func_t clear_idle_mask_func; + +#ifdef CONFIG_SMP + int cpu; /* cpu of this runqueue */ + bool online; + + unsigned int ttwu_pending; + unsigned char nohz_idle_balance; + unsigned char idle_balance; + +#ifdef CONFIG_HAVE_SCHED_AVG_IRQ + struct sched_avg avg_irq; +#endif + + balance_func_t balance_func; + struct balance_arg active_balance_arg ____cacheline_aligned; + struct cpu_stop_work active_balance_work; + + struct balance_callback *balance_callback; +#ifdef CONFIG_HOTPLUG_CPU + struct rcuwait hotplug_wait; +#endif + unsigned int nr_pinned; + +#endif /* CONFIG_SMP */ +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + u64 prev_irq_time; +#endif /* CONFIG_IRQ_TIME_ACCOUNTING */ +#ifdef CONFIG_PARAVIRT + u64 prev_steal_time; +#endif /* CONFIG_PARAVIRT */ +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING + u64 prev_steal_time_rq; +#endif /* CONFIG_PARAVIRT_TIME_ACCOUNTING */ + + /* For genenal cpu load util */ + s32 load_history; + u64 load_block; + u64 load_stamp; + + /* calc_load related fields */ + unsigned long calc_load_update; + long calc_load_active; + + /* Ensure that all clocks are in the same cache line */ + u64 clock ____cacheline_aligned; + u64 clock_task; + + unsigned int nr_running; + unsigned long nr_uninterruptible; + +#ifdef CONFIG_SCHED_HRTICK +#ifdef CONFIG_SMP + call_single_data_t hrtick_csd; +#endif + struct hrtimer hrtick_timer; + ktime_t hrtick_time; +#endif + +#ifdef CONFIG_SCHEDSTATS + + /* latency stats */ + struct sched_info rq_sched_info; + unsigned long long rq_cpu_time; + /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */ + + /* sys_sched_yield() stats */ + unsigned int yld_count; + + /* schedule() stats */ + unsigned int sched_switch; + unsigned int sched_count; + unsigned int sched_goidle; + + /* try_to_wake_up() stats */ + unsigned int ttwu_count; + unsigned int ttwu_local; +#endif /* CONFIG_SCHEDSTATS */ + +#ifdef CONFIG_CPU_IDLE + /* Must be inspected within a rcu lock section */ + struct cpuidle_state *idle_state; +#endif + +#ifdef CONFIG_NO_HZ_COMMON +#ifdef CONFIG_SMP + call_single_data_t nohz_csd; +#endif + atomic_t nohz_flags; +#endif /* CONFIG_NO_HZ_COMMON */ + + /* Scratch cpumask to be temporarily used under rq_lock */ + cpumask_var_t scratch_mask; +}; + +extern unsigned int sysctl_sched_base_slice; + +extern unsigned long rq_load_util(struct rq *rq, unsigned long max); + +extern unsigned long calc_load_update; +extern atomic_long_t calc_load_tasks; + +extern void calc_global_load_tick(struct rq *this_rq); +extern long calc_load_fold_active(struct rq *this_rq, long adjust); + +DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); +#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) +#define this_rq() this_cpu_ptr(&runqueues) +#define task_rq(p) cpu_rq(task_cpu(p)) +#define cpu_curr(cpu) (cpu_rq(cpu)->curr) +#define raw_rq() raw_cpu_ptr(&runqueues) + +#ifdef CONFIG_SMP +#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) +void register_sched_domain_sysctl(void); +void unregister_sched_domain_sysctl(void); +#else +static inline void register_sched_domain_sysctl(void) +{ +} +static inline void unregister_sched_domain_sysctl(void) +{ +} +#endif + +extern bool sched_smp_initialized; + +enum { +#ifdef CONFIG_SCHED_SMT + SMT_LEVEL_SPACE_HOLDER, +#endif + COREGROUP_LEVEL_SPACE_HOLDER, + CORE_LEVEL_SPACE_HOLDER, + OTHER_LEVEL_SPACE_HOLDER, + NR_CPU_AFFINITY_LEVELS +}; + +DECLARE_PER_CPU_ALIGNED(cpumask_t [NR_CPU_AFFINITY_LEVELS], sched_cpu_topo_masks); + +static inline int +__best_mask_cpu(const cpumask_t *cpumask, const cpumask_t *mask) +{ + int cpu; + + while ((cpu = cpumask_any_and(cpumask, mask)) >= nr_cpu_ids) + mask++; + + return cpu; +} + +static inline int best_mask_cpu(int cpu, const cpumask_t *mask) +{ + return __best_mask_cpu(mask, per_cpu(sched_cpu_topo_masks, cpu)); +} + +#endif + +#ifndef arch_scale_freq_tick +static __always_inline +void arch_scale_freq_tick(void) +{ +} +#endif + +#ifndef arch_scale_freq_capacity +static __always_inline +unsigned long arch_scale_freq_capacity(int cpu) +{ + return SCHED_CAPACITY_SCALE; +} +#endif + +static inline u64 __rq_clock_broken(struct rq *rq) +{ + return READ_ONCE(rq->clock); +} + +static inline u64 rq_clock(struct rq *rq) +{ + /* + * Relax lockdep_assert_held() checking as in VRQ, call to + * sched_info_xxxx() may not held rq->lock + * lockdep_assert_held(&rq->lock); + */ + return rq->clock; +} + +static inline u64 rq_clock_task(struct rq *rq) +{ + /* + * Relax lockdep_assert_held() checking as in VRQ, call to + * sched_info_xxxx() may not held rq->lock + * lockdep_assert_held(&rq->lock); + */ + return rq->clock_task; +} + +/* + * {de,en}queue flags: + * + * DEQUEUE_SLEEP - task is no longer runnable + * ENQUEUE_WAKEUP - task just became runnable + * + */ + +#define DEQUEUE_SLEEP 0x01 + +#define ENQUEUE_WAKEUP 0x01 + + +/* + * Below are scheduler API which using in other kernel code + * It use the dummy rq_flags + * ToDo : BMQ need to support these APIs for compatibility with mainline + * scheduler code. + */ +struct rq_flags { + unsigned long flags; +}; + +struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) + __acquires(rq->lock); + +struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) + __acquires(p->pi_lock) + __acquires(rq->lock); + +static inline void __task_rq_unlock(struct rq *rq, struct rq_flags *rf) + __releases(rq->lock) +{ + raw_spin_unlock(&rq->lock); +} + +static inline void +task_rq_unlock(struct rq *rq, struct task_struct *p, struct rq_flags *rf) + __releases(rq->lock) + __releases(p->pi_lock) +{ + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); +} + +static inline void +rq_lock(struct rq *rq, struct rq_flags *rf) + __acquires(rq->lock) +{ + raw_spin_lock(&rq->lock); +} + +static inline void +rq_unlock(struct rq *rq, struct rq_flags *rf) + __releases(rq->lock) +{ + raw_spin_unlock(&rq->lock); +} + +static inline void +rq_lock_irq(struct rq *rq, struct rq_flags *rf) + __acquires(rq->lock) +{ + raw_spin_lock_irq(&rq->lock); +} + +static inline void +rq_unlock_irq(struct rq *rq, struct rq_flags *rf) + __releases(rq->lock) +{ + raw_spin_unlock_irq(&rq->lock); +} + +static inline struct rq * +this_rq_lock_irq(struct rq_flags *rf) + __acquires(rq->lock) +{ + struct rq *rq; + + local_irq_disable(); + rq = this_rq(); + raw_spin_lock(&rq->lock); + + return rq; +} + +static inline raw_spinlock_t *__rq_lockp(struct rq *rq) +{ + return &rq->lock; +} + +static inline raw_spinlock_t *rq_lockp(struct rq *rq) +{ + return __rq_lockp(rq); +} + +static inline void lockdep_assert_rq_held(struct rq *rq) +{ + lockdep_assert_held(__rq_lockp(rq)); +} + +extern void raw_spin_rq_lock_nested(struct rq *rq, int subclass); +extern void raw_spin_rq_unlock(struct rq *rq); + +static inline void raw_spin_rq_lock(struct rq *rq) +{ + raw_spin_rq_lock_nested(rq, 0); +} + +static inline void raw_spin_rq_lock_irq(struct rq *rq) +{ + local_irq_disable(); + raw_spin_rq_lock(rq); +} + +static inline void raw_spin_rq_unlock_irq(struct rq *rq) +{ + raw_spin_rq_unlock(rq); + local_irq_enable(); +} + +static inline int task_current(struct rq *rq, struct task_struct *p) +{ + return rq->curr == p; +} + +static inline bool task_on_cpu(struct task_struct *p) +{ + return p->on_cpu; +} + +extern struct static_key_false sched_schedstats; + +#ifdef CONFIG_CPU_IDLE +static inline void idle_set_state(struct rq *rq, + struct cpuidle_state *idle_state) +{ + rq->idle_state = idle_state; +} + +static inline struct cpuidle_state *idle_get_state(struct rq *rq) +{ + WARN_ON(!rcu_read_lock_held()); + return rq->idle_state; +} +#else +static inline void idle_set_state(struct rq *rq, + struct cpuidle_state *idle_state) +{ +} + +static inline struct cpuidle_state *idle_get_state(struct rq *rq) +{ + return NULL; +} +#endif + +static inline int cpu_of(const struct rq *rq) +{ +#ifdef CONFIG_SMP + return rq->cpu; +#else + return 0; +#endif +} + +extern void resched_cpu(int cpu); + +#include "stats.h" + +#ifdef CONFIG_NO_HZ_COMMON +#define NOHZ_BALANCE_KICK_BIT 0 +#define NOHZ_STATS_KICK_BIT 1 + +#define NOHZ_BALANCE_KICK BIT(NOHZ_BALANCE_KICK_BIT) +#define NOHZ_STATS_KICK BIT(NOHZ_STATS_KICK_BIT) + +#define NOHZ_KICK_MASK (NOHZ_BALANCE_KICK | NOHZ_STATS_KICK) + +#define nohz_flags(cpu) (&cpu_rq(cpu)->nohz_flags) + +/* TODO: needed? +extern void nohz_balance_exit_idle(struct rq *rq); +#else +static inline void nohz_balance_exit_idle(struct rq *rq) { } +*/ +#endif + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING +struct irqtime { + u64 total; + u64 tick_delta; + u64 irq_start_time; + struct u64_stats_sync sync; +}; + +DECLARE_PER_CPU(struct irqtime, cpu_irqtime); + +/* + * Returns the irqtime minus the softirq time computed by ksoftirqd. + * Otherwise ksoftirqd's sum_exec_runtime is substracted its own runtime + * and never move forward. + */ +static inline u64 irq_time_read(int cpu) +{ + struct irqtime *irqtime = &per_cpu(cpu_irqtime, cpu); + unsigned int seq; + u64 total; + + do { + seq = __u64_stats_fetch_begin(&irqtime->sync); + total = irqtime->total; + } while (__u64_stats_fetch_retry(&irqtime->sync, seq)); + + return total; +} +#endif /* CONFIG_IRQ_TIME_ACCOUNTING */ + +#ifdef CONFIG_CPU_FREQ +DECLARE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data); +#endif /* CONFIG_CPU_FREQ */ + +#ifdef CONFIG_NO_HZ_FULL +extern int __init sched_tick_offload_init(void); +#else +static inline int sched_tick_offload_init(void) { return 0; } +#endif + +#ifdef arch_scale_freq_capacity +#ifndef arch_scale_freq_invariant +#define arch_scale_freq_invariant() (true) +#endif +#else /* arch_scale_freq_capacity */ +#define arch_scale_freq_invariant() (false) +#endif + +#ifdef CONFIG_SMP +unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual, + unsigned long min, + unsigned long max); +#endif /* CONFIG_SMP */ + +extern void schedule_idle(void); + +#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT) + +/* + * !! For sched_setattr_nocheck() (kernel) only !! + * + * This is actually gross. :( + * + * It is used to make schedutil kworker(s) higher priority than SCHED_DEADLINE + * tasks, but still be able to sleep. We need this on platforms that cannot + * atomically change clock frequency. Remove once fast switching will be + * available on such platforms. + * + * SUGOV stands for SchedUtil GOVernor. + */ +#define SCHED_FLAG_SUGOV 0x10000000 + +#ifdef CONFIG_MEMBARRIER +/* + * The scheduler provides memory barriers required by membarrier between: + * - prior user-space memory accesses and store to rq->membarrier_state, + * - store to rq->membarrier_state and following user-space memory accesses. + * In the same way it provides those guarantees around store to rq->curr. + */ +static inline void membarrier_switch_mm(struct rq *rq, + struct mm_struct *prev_mm, + struct mm_struct *next_mm) +{ + int membarrier_state; + + if (prev_mm == next_mm) + return; + + membarrier_state = atomic_read(&next_mm->membarrier_state); + if (READ_ONCE(rq->membarrier_state) == membarrier_state) + return; + + WRITE_ONCE(rq->membarrier_state, membarrier_state); +} +#else +static inline void membarrier_switch_mm(struct rq *rq, + struct mm_struct *prev_mm, + struct mm_struct *next_mm) +{ +} +#endif + +#ifdef CONFIG_NUMA +extern int sched_numa_find_closest(const struct cpumask *cpus, int cpu); +#else +static inline int sched_numa_find_closest(const struct cpumask *cpus, int cpu) +{ + return nr_cpu_ids; +} +#endif + +extern void swake_up_all_locked(struct swait_queue_head *q); +extern void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait); + +extern int try_to_wake_up(struct task_struct *tsk, unsigned int state, int wake_flags); + +#ifdef CONFIG_PREEMPT_DYNAMIC +extern int preempt_dynamic_mode; +extern int sched_dynamic_mode(const char *str); +extern void sched_dynamic_update(int mode); +#endif + +static inline void nohz_run_idle_balance(int cpu) { } + +static inline unsigned long +uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + + return SCHED_CAPACITY_SCALE; +} + +static inline bool uclamp_rq_is_capped(struct rq *rq) { return false; } + +static inline bool uclamp_is_used(void) +{ + return false; +} + +static inline unsigned long +uclamp_rq_get(struct rq *rq, enum uclamp_id clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + + return SCHED_CAPACITY_SCALE; +} + +static inline void +uclamp_rq_set(struct rq *rq, enum uclamp_id clamp_id, unsigned int value) +{ +} + +static inline bool uclamp_rq_is_idle(struct rq *rq) +{ + return false; +} + +#ifdef CONFIG_SCHED_MM_CID + +#define SCHED_MM_CID_PERIOD_NS (100ULL * 1000000) /* 100ms */ +#define MM_CID_SCAN_DELAY 100 /* 100ms */ + +extern raw_spinlock_t cid_lock; +extern int use_cid_lock; + +extern void sched_mm_cid_migrate_from(struct task_struct *t); +extern void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t); +extern void task_tick_mm_cid(struct rq *rq, struct task_struct *curr); +extern void init_sched_mm_cid(struct task_struct *t); + +static inline void __mm_cid_put(struct mm_struct *mm, int cid) +{ + if (cid < 0) + return; + cpumask_clear_cpu(cid, mm_cidmask(mm)); +} + +/* + * The per-mm/cpu cid can have the MM_CID_LAZY_PUT flag set or transition to + * the MM_CID_UNSET state without holding the rq lock, but the rq lock needs to + * be held to transition to other states. + * + * State transitions synchronized with cmpxchg or try_cmpxchg need to be + * consistent across cpus, which prevents use of this_cpu_cmpxchg. + */ +static inline void mm_cid_put_lazy(struct task_struct *t) +{ + struct mm_struct *mm = t->mm; + struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid; + int cid; + + lockdep_assert_irqs_disabled(); + cid = __this_cpu_read(pcpu_cid->cid); + if (!mm_cid_is_lazy_put(cid) || + !try_cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, &cid, MM_CID_UNSET)) + return; + __mm_cid_put(mm, mm_cid_clear_lazy_put(cid)); +} + +static inline int mm_cid_pcpu_unset(struct mm_struct *mm) +{ + struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid; + int cid, res; + + lockdep_assert_irqs_disabled(); + cid = __this_cpu_read(pcpu_cid->cid); + for (;;) { + if (mm_cid_is_unset(cid)) + return MM_CID_UNSET; + /* + * Attempt transition from valid or lazy-put to unset. + */ + res = cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, cid, MM_CID_UNSET); + if (res == cid) + break; + cid = res; + } + return cid; +} + +static inline void mm_cid_put(struct mm_struct *mm) +{ + int cid; + + lockdep_assert_irqs_disabled(); + cid = mm_cid_pcpu_unset(mm); + if (cid == MM_CID_UNSET) + return; + __mm_cid_put(mm, mm_cid_clear_lazy_put(cid)); +} + +static inline int __mm_cid_try_get(struct task_struct *t, struct mm_struct *mm) +{ + struct cpumask *cidmask = mm_cidmask(mm); + struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid; + int cid = __this_cpu_read(pcpu_cid->recent_cid); + + /* Try to re-use recent cid. This improves cache locality. */ + if (!mm_cid_is_unset(cid) && !cpumask_test_and_set_cpu(cid, cidmask)) + return cid; + /* + * Expand cid allocation if the maximum number of concurrency + * IDs allocated (max_nr_cid) is below the number cpus allowed + * and number of threads. Expanding cid allocation as much as + * possible improves cache locality. + */ + cid = atomic_read(&mm->max_nr_cid); + while (cid < READ_ONCE(mm->nr_cpus_allowed) && cid < atomic_read(&mm->mm_users)) { + if (!atomic_try_cmpxchg(&mm->max_nr_cid, &cid, cid + 1)) + continue; + if (!cpumask_test_and_set_cpu(cid, cidmask)) + return cid; + } + /* + * Find the first available concurrency id. + * Retry finding first zero bit if the mask is temporarily + * filled. This only happens during concurrent remote-clear + * which owns a cid without holding a rq lock. + */ + for (;;) { + cid = cpumask_first_zero(cidmask); + if (cid < READ_ONCE(mm->nr_cpus_allowed)) + break; + cpu_relax(); + } + if (cpumask_test_and_set_cpu(cid, cidmask)) + return -1; + + return cid; +} + +/* + * Save a snapshot of the current runqueue time of this cpu + * with the per-cpu cid value, allowing to estimate how recently it was used. + */ +static inline void mm_cid_snapshot_time(struct rq *rq, struct mm_struct *mm) +{ + struct mm_cid *pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu_of(rq)); + + lockdep_assert_rq_held(rq); + WRITE_ONCE(pcpu_cid->time, rq->clock); +} + +static inline int __mm_cid_get(struct rq *rq, struct task_struct *t, + struct mm_struct *mm) +{ + int cid; + + /* + * All allocations (even those using the cid_lock) are lock-free. If + * use_cid_lock is set, hold the cid_lock to perform cid allocation to + * guarantee forward progress. + */ + if (!READ_ONCE(use_cid_lock)) { + cid = __mm_cid_try_get(t, mm); + if (cid >= 0) + goto end; + raw_spin_lock(&cid_lock); + } else { + raw_spin_lock(&cid_lock); + cid = __mm_cid_try_get(t, mm); + if (cid >= 0) + goto unlock; + } + + /* + * cid concurrently allocated. Retry while forcing following + * allocations to use the cid_lock to ensure forward progress. + */ + WRITE_ONCE(use_cid_lock, 1); + /* + * Set use_cid_lock before allocation. Only care about program order + * because this is only required for forward progress. + */ + barrier(); + /* + * Retry until it succeeds. It is guaranteed to eventually succeed once + * all newcoming allocations observe the use_cid_lock flag set. + */ + do { + cid = __mm_cid_try_get(t, mm); + cpu_relax(); + } while (cid < 0); + /* + * Allocate before clearing use_cid_lock. Only care about + * program order because this is for forward progress. + */ + barrier(); + WRITE_ONCE(use_cid_lock, 0); +unlock: + raw_spin_unlock(&cid_lock); +end: + mm_cid_snapshot_time(rq, mm); + return cid; +} + +static inline int mm_cid_get(struct rq *rq, struct task_struct *t, + struct mm_struct *mm) +{ + struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid; + struct cpumask *cpumask; + int cid; + + lockdep_assert_rq_held(rq); + cpumask = mm_cidmask(mm); + cid = __this_cpu_read(pcpu_cid->cid); + if (mm_cid_is_valid(cid)) { + mm_cid_snapshot_time(rq, mm); + return cid; + } + if (mm_cid_is_lazy_put(cid)) { + if (try_cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, &cid, MM_CID_UNSET)) + __mm_cid_put(mm, mm_cid_clear_lazy_put(cid)); + } + cid = __mm_cid_get(rq, t, mm); + __this_cpu_write(pcpu_cid->cid, cid); + __this_cpu_write(pcpu_cid->recent_cid, cid); + + return cid; +} + +static inline void switch_mm_cid(struct rq *rq, + struct task_struct *prev, + struct task_struct *next) +{ + /* + * Provide a memory barrier between rq->curr store and load of + * {prev,next}->mm->pcpu_cid[cpu] on rq->curr->mm transition. + * + * Should be adapted if context_switch() is modified. + */ + if (!next->mm) { // to kernel + /* + * user -> kernel transition does not guarantee a barrier, but + * we can use the fact that it performs an atomic operation in + * mmgrab(). + */ + if (prev->mm) // from user + smp_mb__after_mmgrab(); + /* + * kernel -> kernel transition does not change rq->curr->mm + * state. It stays NULL. + */ + } else { // to user + /* + * kernel -> user transition does not provide a barrier + * between rq->curr store and load of {prev,next}->mm->pcpu_cid[cpu]. + * Provide it here. + */ + if (!prev->mm) // from kernel + smp_mb(); + /* + * user -> user transition guarantees a memory barrier through + * switch_mm() when current->mm changes. If current->mm is + * unchanged, no barrier is needed. + */ + } + if (prev->mm_cid_active) { + mm_cid_snapshot_time(rq, prev->mm); + mm_cid_put_lazy(prev); + prev->mm_cid = -1; + } + if (next->mm_cid_active) + next->last_mm_cid = next->mm_cid = mm_cid_get(rq, next, next->mm); +} + +#else +static inline void switch_mm_cid(struct rq *rq, struct task_struct *prev, struct task_struct *next) { } +static inline void sched_mm_cid_migrate_from(struct task_struct *t) { } +static inline void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t) { } +static inline void task_tick_mm_cid(struct rq *rq, struct task_struct *curr) { } +static inline void init_sched_mm_cid(struct task_struct *t) { } +#endif + +#ifdef CONFIG_SMP +extern struct balance_callback balance_push_callback; + +static inline void +queue_balance_callback(struct rq *rq, + struct balance_callback *head, + void (*func)(struct rq *rq)) +{ + lockdep_assert_rq_held(rq); + + /* + * Don't (re)queue an already queued item; nor queue anything when + * balance_push() is active, see the comment with + * balance_push_callback. + */ + if (unlikely(head->next || rq->balance_callback == &balance_push_callback)) + return; + + head->func = func; + head->next = rq->balance_callback; + rq->balance_callback = head; +} +#endif /* CONFIG_SMP */ + +#ifdef CONFIG_SCHED_BMQ +#include "bmq.h" +#endif +#ifdef CONFIG_SCHED_PDS +#include "pds.h" +#endif + +#endif /* _KERNEL_SCHED_ALT_SCHED_H */ diff --git a/kernel/sched/alt_topology.c b/kernel/sched/alt_topology.c new file mode 100644 index 000000000..2266138ee --- /dev/null +++ b/kernel/sched/alt_topology.c @@ -0,0 +1,350 @@ +#include "alt_core.h" +#include "alt_topology.h" + +#ifdef CONFIG_SMP + +static cpumask_t sched_pcore_mask ____cacheline_aligned_in_smp; + +static int __init sched_pcore_mask_setup(char *str) +{ + if (cpulist_parse(str, &sched_pcore_mask)) + pr_warn("sched/alt: pcore_cpus= incorrect CPU range\n"); + + return 0; +} +__setup("pcore_cpus=", sched_pcore_mask_setup); + +/* + * set/clear idle mask functions + */ +#ifdef CONFIG_SCHED_SMT +static void set_idle_mask_smt(unsigned int cpu, struct cpumask *dstp) +{ + cpumask_set_cpu(cpu, dstp); + if (cpumask_subset(cpu_smt_mask(cpu), sched_idle_mask)) + cpumask_or(sched_sg_idle_mask, sched_sg_idle_mask, cpu_smt_mask(cpu)); +} + +static void clear_idle_mask_smt(int cpu, struct cpumask *dstp) +{ + cpumask_clear_cpu(cpu, dstp); + cpumask_andnot(sched_sg_idle_mask, sched_sg_idle_mask, cpu_smt_mask(cpu)); +} +#endif + +static void set_idle_mask_pcore(unsigned int cpu, struct cpumask *dstp) +{ + cpumask_set_cpu(cpu, dstp); + cpumask_set_cpu(cpu, sched_pcore_idle_mask); +} + +static void clear_idle_mask_pcore(int cpu, struct cpumask *dstp) +{ + cpumask_clear_cpu(cpu, dstp); + cpumask_clear_cpu(cpu, sched_pcore_idle_mask); +} + +static void set_idle_mask_ecore(unsigned int cpu, struct cpumask *dstp) +{ + cpumask_set_cpu(cpu, dstp); + cpumask_set_cpu(cpu, sched_ecore_idle_mask); +} + +static void clear_idle_mask_ecore(int cpu, struct cpumask *dstp) +{ + cpumask_clear_cpu(cpu, dstp); + cpumask_clear_cpu(cpu, sched_ecore_idle_mask); +} + +/* + * Idle cpu/rq selection functions + */ +#ifdef CONFIG_SCHED_SMT +static bool p1_idle_select_func(struct cpumask *dstp, const struct cpumask *src1p, + const struct cpumask *src2p) +{ + return cpumask_and(dstp, src1p, src2p + 1) || + cpumask_and(dstp, src1p, src2p); +} +#endif + +static bool p1p2_idle_select_func(struct cpumask *dstp, const struct cpumask *src1p, + const struct cpumask *src2p) +{ + return cpumask_and(dstp, src1p, src2p + 1) || + cpumask_and(dstp, src1p, src2p + 2) || + cpumask_and(dstp, src1p, src2p); +} + +/* common balance functions */ +static int active_balance_cpu_stop(void *data) +{ + struct balance_arg *arg = data; + struct task_struct *p = arg->task; + struct rq *rq = this_rq(); + unsigned long flags; + cpumask_t tmp; + + local_irq_save(flags); + + raw_spin_lock(&p->pi_lock); + raw_spin_lock(&rq->lock); + + arg->active = 0; + + if (task_on_rq_queued(p) && task_rq(p) == rq && + cpumask_and(&tmp, p->cpus_ptr, arg->cpumask) && + !is_migration_disabled(p)) { + int dcpu = __best_mask_cpu(&tmp, per_cpu(sched_cpu_llc_mask, cpu_of(rq))); + rq = move_queued_task(rq, p, dcpu); + } + + raw_spin_unlock(&rq->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + + return 0; +} + +/* trigger_active_balance - for @rq */ +static inline int +trigger_active_balance(struct rq *src_rq, struct rq *rq, cpumask_t *target_mask) +{ + struct balance_arg *arg; + unsigned long flags; + struct task_struct *p; + int res; + + if (!raw_spin_trylock_irqsave(&rq->lock, flags)) + return 0; + + arg = &rq->active_balance_arg; + res = (1 == rq->nr_running) && \ + !is_migration_disabled((p = sched_rq_first_task(rq))) && \ + cpumask_intersects(p->cpus_ptr, target_mask) && \ + !arg->active; + if (res) { + arg->task = p; + arg->cpumask = target_mask; + + arg->active = 1; + } + + raw_spin_unlock_irqrestore(&rq->lock, flags); + + if (res) { + preempt_disable(); + raw_spin_unlock(&src_rq->lock); + + stop_one_cpu_nowait(cpu_of(rq), active_balance_cpu_stop, arg, + &rq->active_balance_work); + + preempt_enable(); + raw_spin_lock(&src_rq->lock); + } + + return res; +} + +static inline int +ecore_source_balance(struct rq *rq, cpumask_t *single_task_mask, cpumask_t *target_mask) +{ + if (cpumask_andnot(single_task_mask, single_task_mask, &sched_pcore_mask)) { + int i, cpu = cpu_of(rq); + + for_each_cpu_wrap(i, single_task_mask, cpu) + if (trigger_active_balance(rq, cpu_rq(i), target_mask)) + return 1; + } + + return 0; +} + +static DEFINE_PER_CPU(struct balance_callback, active_balance_head); + +#ifdef CONFIG_SCHED_SMT +static inline int +smt_pcore_source_balance(struct rq *rq, cpumask_t *single_task_mask, cpumask_t *target_mask) +{ + cpumask_t smt_single_mask; + + if (cpumask_and(&smt_single_mask, single_task_mask, &sched_smt_mask)) { + int i, cpu = cpu_of(rq); + + for_each_cpu_wrap(i, &smt_single_mask, cpu) { + if (cpumask_subset(cpu_smt_mask(i), &smt_single_mask) && + trigger_active_balance(rq, cpu_rq(i), target_mask)) + return 1; + } + } + + return 0; +} + +/* smt p core balance functions */ +static inline void smt_pcore_balance(struct rq *rq) +{ + cpumask_t single_task_mask; + + if (cpumask_andnot(&single_task_mask, cpu_active_mask, sched_idle_mask) && + cpumask_andnot(&single_task_mask, &single_task_mask, &sched_rq_pending_mask) && + (/* smt core group balance */ + (static_key_count(&sched_smt_present.key) > 1 && + smt_pcore_source_balance(rq, &single_task_mask, sched_sg_idle_mask) + ) || + /* e core to idle smt core balance */ + ecore_source_balance(rq, &single_task_mask, sched_sg_idle_mask))) + return; +} + +static void smt_pcore_balance_func(struct rq *rq, const int cpu) +{ + if (cpumask_test_cpu(cpu, sched_sg_idle_mask)) + queue_balance_callback(rq, &per_cpu(active_balance_head, cpu), smt_pcore_balance); +} + +/* smt balance functions */ +static inline void smt_balance(struct rq *rq) +{ + cpumask_t single_task_mask; + + if (cpumask_andnot(&single_task_mask, cpu_active_mask, sched_idle_mask) && + cpumask_andnot(&single_task_mask, &single_task_mask, &sched_rq_pending_mask) && + static_key_count(&sched_smt_present.key) > 1 && + smt_pcore_source_balance(rq, &single_task_mask, sched_sg_idle_mask)) + return; +} + +static void smt_balance_func(struct rq *rq, const int cpu) +{ + if (cpumask_test_cpu(cpu, sched_sg_idle_mask)) + queue_balance_callback(rq, &per_cpu(active_balance_head, cpu), smt_balance); +} + +/* e core balance functions */ +static inline void ecore_balance(struct rq *rq) +{ + cpumask_t single_task_mask; + + if (cpumask_andnot(&single_task_mask, cpu_active_mask, sched_idle_mask) && + cpumask_andnot(&single_task_mask, &single_task_mask, &sched_rq_pending_mask) && + /* smt occupied p core to idle e core balance */ + smt_pcore_source_balance(rq, &single_task_mask, sched_ecore_idle_mask)) + return; +} + +static void ecore_balance_func(struct rq *rq, const int cpu) +{ + queue_balance_callback(rq, &per_cpu(active_balance_head, cpu), ecore_balance); +} +#endif /* CONFIG_SCHED_SMT */ + +/* p core balance functions */ +static inline void pcore_balance(struct rq *rq) +{ + cpumask_t single_task_mask; + + if (cpumask_andnot(&single_task_mask, cpu_active_mask, sched_idle_mask) && + cpumask_andnot(&single_task_mask, &single_task_mask, &sched_rq_pending_mask) && + /* idle e core to p core balance */ + ecore_source_balance(rq, &single_task_mask, sched_pcore_idle_mask)) + return; +} + +static void pcore_balance_func(struct rq *rq, const int cpu) +{ + queue_balance_callback(rq, &per_cpu(active_balance_head, cpu), pcore_balance); +} + +#ifdef ALT_SCHED_DEBUG +#define SCHED_DEBUG_INFO(...) printk(KERN_INFO __VA_ARGS__) +#else +#define SCHED_DEBUG_INFO(...) do { } while(0) +#endif + +#define SET_IDLE_SELECT_FUNC(func) \ +{ \ + idle_select_func = func; \ + printk(KERN_INFO "sched: "#func); \ +} + +#define SET_RQ_BALANCE_FUNC(rq, cpu, func) \ +{ \ + rq->balance_func = func; \ + SCHED_DEBUG_INFO("sched: cpu#%02d -> "#func, cpu); \ +} + +#define SET_RQ_IDLE_MASK_FUNC(rq, cpu, set_func, clear_func) \ +{ \ + rq->set_idle_mask_func = set_func; \ + rq->clear_idle_mask_func = clear_func; \ + SCHED_DEBUG_INFO("sched: cpu#%02d -> "#set_func" "#clear_func, cpu); \ +} + +void sched_init_topology(void) +{ + int cpu; + struct rq *rq; + cpumask_t sched_ecore_mask = { CPU_BITS_NONE }; + int ecore_present = 0; + +#ifdef CONFIG_SCHED_SMT + if (!cpumask_empty(&sched_smt_mask)) + printk(KERN_INFO "sched: smt mask: 0x%08lx\n", sched_smt_mask.bits[0]); +#endif + + if (!cpumask_empty(&sched_pcore_mask)) { + cpumask_andnot(&sched_ecore_mask, cpu_online_mask, &sched_pcore_mask); + printk(KERN_INFO "sched: pcore mask: 0x%08lx, ecore mask: 0x%08lx\n", + sched_pcore_mask.bits[0], sched_ecore_mask.bits[0]); + + ecore_present = !cpumask_empty(&sched_ecore_mask); + } + +#ifdef CONFIG_SCHED_SMT + /* idle select function */ + if (cpumask_equal(&sched_smt_mask, cpu_online_mask)) { + SET_IDLE_SELECT_FUNC(p1_idle_select_func); + } else +#endif + if (!cpumask_empty(&sched_pcore_mask)) { + SET_IDLE_SELECT_FUNC(p1p2_idle_select_func); + } + + for_each_online_cpu(cpu) { + rq = cpu_rq(cpu); + /* take chance to reset time slice for idle tasks */ + rq->idle->time_slice = sysctl_sched_base_slice; + +#ifdef CONFIG_SCHED_SMT + if (cpumask_weight(cpu_smt_mask(cpu)) > 1) { + SET_RQ_IDLE_MASK_FUNC(rq, cpu, set_idle_mask_smt, clear_idle_mask_smt); + + if (cpumask_test_cpu(cpu, &sched_pcore_mask) && + !cpumask_intersects(&sched_ecore_mask, &sched_smt_mask)) { + SET_RQ_BALANCE_FUNC(rq, cpu, smt_pcore_balance_func); + } else { + SET_RQ_BALANCE_FUNC(rq, cpu, smt_balance_func); + } + + continue; + } +#endif + /* !SMT or only one cpu in sg */ + if (cpumask_test_cpu(cpu, &sched_pcore_mask)) { + SET_RQ_IDLE_MASK_FUNC(rq, cpu, set_idle_mask_pcore, clear_idle_mask_pcore); + + if (ecore_present) + SET_RQ_BALANCE_FUNC(rq, cpu, pcore_balance_func); + + continue; + } + if (cpumask_test_cpu(cpu, &sched_ecore_mask)) { + SET_RQ_IDLE_MASK_FUNC(rq, cpu, set_idle_mask_ecore, clear_idle_mask_ecore); +#ifdef CONFIG_SCHED_SMT + if (cpumask_intersects(&sched_pcore_mask, &sched_smt_mask)) + SET_RQ_BALANCE_FUNC(rq, cpu, ecore_balance_func); +#endif + } + } +} +#endif /* CONFIG_SMP */ diff --git a/kernel/sched/alt_topology.h b/kernel/sched/alt_topology.h new file mode 100644 index 000000000..076174cd2 --- /dev/null +++ b/kernel/sched/alt_topology.h @@ -0,0 +1,6 @@ +#ifndef _KERNEL_SCHED_ALT_TOPOLOGY_H +#define _KERNEL_SCHED_ALT_TOPOLOGY_H + +extern void sched_init_topology(void); + +#endif /* _KERNEL_SCHED_ALT_TOPOLOGY_H */ diff --git a/kernel/sched/bmq.h b/kernel/sched/bmq.h new file mode 100644 index 000000000..5a7835246 --- /dev/null +++ b/kernel/sched/bmq.h @@ -0,0 +1,103 @@ +#ifndef _KERNEL_SCHED_BMQ_H +#define _KERNEL_SCHED_BMQ_H + +#define ALT_SCHED_NAME "BMQ" + +/* + * BMQ only routines + */ +static inline void boost_task(struct task_struct *p, int n) +{ + int limit; + + switch (p->policy) { + case SCHED_NORMAL: + limit = -MAX_PRIORITY_ADJ; + break; + case SCHED_BATCH: + limit = 0; + break; + default: + return; + } + + p->boost_prio = max(limit, p->boost_prio - n); +} + +static inline void deboost_task(struct task_struct *p) +{ + if (p->boost_prio < MAX_PRIORITY_ADJ) + p->boost_prio++; +} + +/* + * Common interfaces + */ +static inline void sched_timeslice_imp(const int timeslice_ms) {} + +/* This API is used in task_prio(), return value readed by human users */ +static inline int +task_sched_prio_normal(const struct task_struct *p, const struct rq *rq) +{ + return p->prio + p->boost_prio - MIN_NORMAL_PRIO; +} + +static inline int task_sched_prio(const struct task_struct *p) +{ + return (p->prio < MIN_NORMAL_PRIO)? (p->prio >> 2) : + MIN_SCHED_NORMAL_PRIO + (p->prio + p->boost_prio - MIN_NORMAL_PRIO) / 2; +} + +#define TASK_SCHED_PRIO_IDX(p, rq, idx, prio) \ + prio = task_sched_prio(p); \ + idx = prio; + +static inline int sched_prio2idx(int prio, struct rq *rq) +{ + return prio; +} + +static inline int sched_idx2prio(int idx, struct rq *rq) +{ + return idx; +} + +static inline int sched_rq_prio_idx(struct rq *rq) +{ + return rq->prio; +} + +static inline int task_running_nice(struct task_struct *p) +{ + return (p->prio + p->boost_prio > DEFAULT_PRIO); +} + +static inline void sched_update_rq_clock(struct rq *rq) {} + +static inline void sched_task_renew(struct task_struct *p, const struct rq *rq) +{ + deboost_task(p); +} + +static inline void sched_task_sanity_check(struct task_struct *p, struct rq *rq) {} +static inline void sched_task_fork(struct task_struct *p, struct rq *rq) {} + +static inline void do_sched_yield_type_1(struct task_struct *p, struct rq *rq) +{ + p->boost_prio = MAX_PRIORITY_ADJ; +} + +static inline void sched_task_ttwu(struct task_struct *p) +{ + s64 delta = this_rq()->clock_task > p->last_ran; + + if (likely(delta > 0)) + boost_task(p, delta >> 22); +} + +static inline void sched_task_deactivate(struct task_struct *p, struct rq *rq) +{ + boost_task(p, 1); +} + +#endif /* _KERNEL_SCHED_BMQ_H */ diff --git a/kernel/sched/build_policy.c b/kernel/sched/build_policy.c index fae1f5c92..1e06434b5 100644 --- a/kernel/sched/build_policy.c +++ b/kernel/sched/build_policy.c @@ -49,15 +49,21 @@ #include "idle.c" +#ifndef CONFIG_SCHED_ALT #include "rt.c" +#endif #ifdef CONFIG_SMP +#ifndef CONFIG_SCHED_ALT # include "cpudeadline.c" +#endif # include "pelt.c" #endif #include "cputime.c" +#ifndef CONFIG_SCHED_ALT #include "deadline.c" +#endif #ifdef CONFIG_SCHED_CLASS_EXT # include "ext.c" diff --git a/kernel/sched/build_utility.c b/kernel/sched/build_utility.c index 80a3df49a..58d04aa73 100644 --- a/kernel/sched/build_utility.c +++ b/kernel/sched/build_utility.c @@ -56,6 +56,10 @@ #include "clock.c" +#ifdef CONFIG_SCHED_ALT +# include "alt_topology.c" +#endif + #ifdef CONFIG_CGROUP_CPUACCT # include "cpuacct.c" #endif @@ -84,7 +88,9 @@ #ifdef CONFIG_SMP # include "cpupri.c" +#ifndef CONFIG_SCHED_ALT # include "stop_task.c" +#endif # include "topology.c" #endif diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e51d5ce73..df73275fe 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -197,6 +197,7 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual, static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost) { +#ifndef CONFIG_SCHED_ALT unsigned long min, max, util = scx_cpuperf_target(sg_cpu->cpu); if (!scx_switched_all()) @@ -205,6 +206,10 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost) util = max(util, boost); sg_cpu->bw_min = min; sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max); +#else /* CONFIG_SCHED_ALT */ + sg_cpu->bw_min = 0; + sg_cpu->util = rq_load_util(cpu_rq(sg_cpu->cpu), arch_scale_cpu_capacity(sg_cpu->cpu)); +#endif /* CONFIG_SCHED_ALT */ } /** @@ -364,8 +369,10 @@ static inline bool sugov_hold_freq(struct sugov_cpu *sg_cpu) { return false; } */ static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu) { +#ifndef CONFIG_SCHED_ALT if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_min) sg_cpu->sg_policy->limits_changed = true; +#endif } static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu, @@ -684,6 +691,7 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy) } ret = sched_setattr_nocheck(thread, &attr); + if (ret) { kthread_stop(thread); pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__); diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 0bed0fa1a..031affa09 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -126,7 +126,7 @@ void account_user_time(struct task_struct *p, u64 cputime) p->utime += cputime; account_group_user_time(p, cputime); - index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER; + index = task_running_nice(p) ? CPUTIME_NICE : CPUTIME_USER; /* Add user time to cpustat. */ task_group_account_field(p, index, cputime); @@ -150,7 +150,7 @@ void account_guest_time(struct task_struct *p, u64 cputime) p->gtime += cputime; /* Add guest time to cpustat. */ - if (task_nice(p) > 0) { + if (task_running_nice(p)) { task_group_account_field(p, CPUTIME_NICE, cputime); cpustat[CPUTIME_GUEST_NICE] += cputime; } else { @@ -288,7 +288,7 @@ static inline u64 account_other_time(u64 max) #ifdef CONFIG_64BIT static inline u64 read_sum_exec_runtime(struct task_struct *t) { - return t->se.sum_exec_runtime; + return tsk_seruntime(t); } #else static u64 read_sum_exec_runtime(struct task_struct *t) @@ -298,7 +298,7 @@ static u64 read_sum_exec_runtime(struct task_struct *t) struct rq *rq; rq = task_rq_lock(t, &rf); - ns = t->se.sum_exec_runtime; + ns = tsk_seruntime(t); task_rq_unlock(rq, t, &rf); return ns; @@ -623,7 +623,7 @@ void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev, void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st) { struct task_cputime cputime = { - .sum_exec_runtime = p->se.sum_exec_runtime, + .sum_exec_runtime = tsk_seruntime(p), }; if (task_cputime(p, &cputime.utime, &cputime.stime)) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index a1be00a98..e9ebc8e5b 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -7,6 +7,7 @@ * Copyright(C) 2007, Red Hat, Inc., Ingo Molnar */ +#ifndef CONFIG_SCHED_ALT /* * This allows printing both to /sys/kernel/debug/sched/debug and * to the console @@ -215,6 +216,7 @@ static const struct file_operations sched_scaling_fops = { }; #endif /* SMP */ +#endif /* !CONFIG_SCHED_ALT */ #ifdef CONFIG_PREEMPT_DYNAMIC @@ -279,6 +281,7 @@ static const struct file_operations sched_dynamic_fops = { #endif /* CONFIG_PREEMPT_DYNAMIC */ +#ifndef CONFIG_SCHED_ALT __read_mostly bool sched_debug_verbose; #ifdef CONFIG_SMP @@ -469,9 +472,11 @@ static const struct file_operations fair_server_period_fops = { .llseek = seq_lseek, .release = single_release, }; +#endif /* !CONFIG_SCHED_ALT */ static struct dentry *debugfs_sched; +#ifndef CONFIG_SCHED_ALT static void debugfs_fair_server_init(void) { struct dentry *d_fair; @@ -492,6 +497,7 @@ static void debugfs_fair_server_init(void) debugfs_create_file("period", 0644, d_cpu, (void *) cpu, &fair_server_period_fops); } } +#endif /* !CONFIG_SCHED_ALT */ static __init int sched_init_debug(void) { @@ -499,14 +505,17 @@ static __init int sched_init_debug(void) debugfs_sched = debugfs_create_dir("sched", NULL); +#ifndef CONFIG_SCHED_ALT debugfs_create_file("features", 0644, debugfs_sched, NULL, &sched_feat_fops); debugfs_create_file_unsafe("verbose", 0644, debugfs_sched, &sched_debug_verbose, &sched_verbose_fops); +#endif /* !CONFIG_SCHED_ALT */ #ifdef CONFIG_PREEMPT_DYNAMIC debugfs_create_file("preempt", 0644, debugfs_sched, NULL, &sched_dynamic_fops); #endif debugfs_create_u32("base_slice_ns", 0644, debugfs_sched, &sysctl_sched_base_slice); +#ifndef CONFIG_SCHED_ALT debugfs_create_u32("latency_warn_ms", 0644, debugfs_sched, &sysctl_resched_latency_warn_ms); debugfs_create_u32("latency_warn_once", 0644, debugfs_sched, &sysctl_resched_latency_warn_once); @@ -531,13 +540,17 @@ static __init int sched_init_debug(void) #endif debugfs_create_file("debug", 0444, debugfs_sched, NULL, &sched_debug_fops); +#endif /* !CONFIG_SCHED_ALT */ +#ifndef CONFIG_SCHED_ALT debugfs_fair_server_init(); +#endif /* !CONFIG_SCHED_ALT */ return 0; } late_initcall(sched_init_debug); +#ifndef CONFIG_SCHED_ALT #ifdef CONFIG_SMP static cpumask_var_t sd_sysctl_cpus; @@ -1290,6 +1303,7 @@ void proc_sched_set_task(struct task_struct *p) memset(&p->stats, 0, sizeof(p->stats)); #endif } +#endif /* !CONFIG_SCHED_ALT */ void resched_latency_warn(int cpu, u64 latency) { diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 2c85c86b4..4369a4b12 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -423,6 +423,7 @@ void cpu_startup_entry(enum cpuhp_state state) do_idle(); } +#ifndef CONFIG_SCHED_ALT /* * idle-task scheduling class. */ @@ -538,3 +539,4 @@ DEFINE_SCHED_CLASS(idle) = { .switched_to = switched_to_idle, .update_curr = update_curr_idle, }; +#endif diff --git a/kernel/sched/pds.h b/kernel/sched/pds.h new file mode 100644 index 000000000..fe3099071 --- /dev/null +++ b/kernel/sched/pds.h @@ -0,0 +1,139 @@ +#ifndef _KERNEL_SCHED_PDS_H +#define _KERNEL_SCHED_PDS_H + +#define ALT_SCHED_NAME "PDS" + +static const u64 RT_MASK = ((1ULL << MIN_SCHED_NORMAL_PRIO) - 1); + +#define SCHED_NORMAL_PRIO_NUM (32) +#define SCHED_EDGE_DELTA (SCHED_NORMAL_PRIO_NUM - NICE_WIDTH / 2) + +/* PDS assume SCHED_NORMAL_PRIO_NUM is power of 2 */ +#define SCHED_NORMAL_PRIO_MOD(x) ((x) & (SCHED_NORMAL_PRIO_NUM - 1)) + +/* default time slice 4ms -> shift 22, 2 time slice slots -> shift 23 */ +static __read_mostly int sched_timeslice_shift = 23; + +/* + * Common interfaces + */ +static inline int +task_sched_prio_normal(const struct task_struct *p, const struct rq *rq) +{ + u64 sched_dl = max(p->deadline, rq->time_edge); + +#ifdef ALT_SCHED_DEBUG + if (WARN_ONCE(sched_dl - rq->time_edge > NORMAL_PRIO_NUM - 1, + "pds: task_sched_prio_normal() delta %lld\n", sched_dl - rq->time_edge)) + return SCHED_NORMAL_PRIO_NUM - 1; +#endif + + return sched_dl - rq->time_edge; +} + +static inline int task_sched_prio(const struct task_struct *p) +{ + return (p->prio < MIN_NORMAL_PRIO) ? (p->prio >> 2) : + MIN_SCHED_NORMAL_PRIO + task_sched_prio_normal(p, task_rq(p)); +} + +#define TASK_SCHED_PRIO_IDX(p, rq, idx, prio) \ + if (p->prio < MIN_NORMAL_PRIO) { \ + prio = p->prio >> 2; \ + idx = prio; \ + } else { \ + u64 sched_dl = max(p->deadline, rq->time_edge); \ + prio = MIN_SCHED_NORMAL_PRIO + sched_dl - rq->time_edge; \ + idx = MIN_SCHED_NORMAL_PRIO + SCHED_NORMAL_PRIO_MOD(sched_dl); \ + } + +static inline int sched_prio2idx(int sched_prio, struct rq *rq) +{ + return (IDLE_TASK_SCHED_PRIO == sched_prio || sched_prio < MIN_SCHED_NORMAL_PRIO) ? + sched_prio : + MIN_SCHED_NORMAL_PRIO + SCHED_NORMAL_PRIO_MOD(sched_prio + rq->time_edge); +} + +static inline int sched_idx2prio(int sched_idx, struct rq *rq) +{ + return (sched_idx < MIN_SCHED_NORMAL_PRIO) ? + sched_idx : + MIN_SCHED_NORMAL_PRIO + SCHED_NORMAL_PRIO_MOD(sched_idx - rq->time_edge); +} + +static inline int sched_rq_prio_idx(struct rq *rq) +{ + return rq->prio_idx; +} + +static inline int task_running_nice(struct task_struct *p) +{ + return (p->prio > DEFAULT_PRIO); +} + +static inline void sched_update_rq_clock(struct rq *rq) +{ + struct list_head head; + u64 old = rq->time_edge; + u64 now = rq->clock >> sched_timeslice_shift; + u64 prio, delta; + DECLARE_BITMAP(normal, SCHED_QUEUE_BITS); + + if (now == old) + return; + + rq->time_edge = now; + delta = min_t(u64, SCHED_NORMAL_PRIO_NUM, now - old); + INIT_LIST_HEAD(&head); + + prio = MIN_SCHED_NORMAL_PRIO; + for_each_set_bit_from(prio, rq->queue.bitmap, MIN_SCHED_NORMAL_PRIO + delta) + list_splice_tail_init(rq->queue.heads + MIN_SCHED_NORMAL_PRIO + + SCHED_NORMAL_PRIO_MOD(prio + old), &head); + + bitmap_shift_right(normal, rq->queue.bitmap, delta, SCHED_QUEUE_BITS); + if (!list_empty(&head)) { + u64 idx = MIN_SCHED_NORMAL_PRIO + SCHED_NORMAL_PRIO_MOD(now); + + __list_splice(&head, rq->queue.heads + idx, rq->queue.heads[idx].next); + set_bit(MIN_SCHED_NORMAL_PRIO, normal); + } + bitmap_replace(rq->queue.bitmap, normal, rq->queue.bitmap, + (const unsigned long *)&RT_MASK, SCHED_QUEUE_BITS); + + if (rq->prio < MIN_SCHED_NORMAL_PRIO || IDLE_TASK_SCHED_PRIO == rq->prio) + return; + + rq->prio = max_t(u64, MIN_SCHED_NORMAL_PRIO, rq->prio - delta); + rq->prio_idx = sched_prio2idx(rq->prio, rq); +} + +static inline void sched_task_renew(struct task_struct *p, const struct rq *rq) +{ + if (p->prio >= MIN_NORMAL_PRIO) + p->deadline = rq->time_edge + SCHED_EDGE_DELTA + + (p->static_prio - (MAX_PRIO - NICE_WIDTH)) / 2; +} + +static inline void sched_task_sanity_check(struct task_struct *p, struct rq *rq) +{ + u64 max_dl = rq->time_edge + SCHED_EDGE_DELTA + NICE_WIDTH / 2 - 1; + if (unlikely(p->deadline > max_dl)) + p->deadline = max_dl; +} + +static inline void sched_task_fork(struct task_struct *p, struct rq *rq) +{ + sched_task_renew(p, rq); +} + +static inline void do_sched_yield_type_1(struct task_struct *p, struct rq *rq) +{ + p->time_slice = sysctl_sched_base_slice; + sched_task_renew(p, rq); +} + +static inline void sched_task_ttwu(struct task_struct *p) {} +static inline void sched_task_deactivate(struct task_struct *p, struct rq *rq) {} + +#endif /* _KERNEL_SCHED_PDS_H */ diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c index fee75cc2c..f3b80e50e 100644 --- a/kernel/sched/pelt.c +++ b/kernel/sched/pelt.c @@ -266,6 +266,7 @@ ___update_load_avg(struct sched_avg *sa, unsigned long load) WRITE_ONCE(sa->util_avg, sa->util_sum / divider); } +#ifndef CONFIG_SCHED_ALT /* * sched_entity: * @@ -383,8 +384,9 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running) return 0; } +#endif -#ifdef CONFIG_SCHED_HW_PRESSURE +#if defined(CONFIG_SCHED_HW_PRESSURE) && !defined(CONFIG_SCHED_ALT) /* * hardware: * @@ -468,6 +470,7 @@ int update_irq_load_avg(struct rq *rq, u64 running) } #endif +#ifndef CONFIG_SCHED_ALT /* * Load avg and utiliztion metrics need to be updated periodically and before * consumption. This function updates the metrics for all subsystems except for @@ -487,3 +490,4 @@ bool update_other_load_avgs(struct rq *rq) update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure) | update_irq_load_avg(rq, 0); } +#endif /* !CONFIG_SCHED_ALT */ diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h index f4f6a0875..ee780f2b6 100644 --- a/kernel/sched/pelt.h +++ b/kernel/sched/pelt.h @@ -1,14 +1,16 @@ #ifdef CONFIG_SMP #include "sched-pelt.h" +#ifndef CONFIG_SCHED_ALT int __update_load_avg_blocked_se(u64 now, struct sched_entity *se); int __update_load_avg_se(u64 now, struct cfs_rq *cfs_rq, struct sched_entity *se); int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq); int update_rt_rq_load_avg(u64 now, struct rq *rq, int running); int update_dl_rq_load_avg(u64 now, struct rq *rq, int running); bool update_other_load_avgs(struct rq *rq); +#endif -#ifdef CONFIG_SCHED_HW_PRESSURE +#if defined(CONFIG_SCHED_HW_PRESSURE) && !defined(CONFIG_SCHED_ALT) int update_hw_load_avg(u64 now, struct rq *rq, u64 capacity); static inline u64 hw_load_avg(struct rq *rq) @@ -45,6 +47,7 @@ static inline u32 get_pelt_divider(struct sched_avg *avg) return PELT_MIN_DIVIDER + avg->period_contrib; } +#ifndef CONFIG_SCHED_ALT static inline void cfs_se_util_change(struct sched_avg *avg) { unsigned int enqueued; @@ -181,9 +184,11 @@ static inline u64 cfs_rq_clock_pelt(struct cfs_rq *cfs_rq) return rq_clock_pelt(rq_of(cfs_rq)); } #endif +#endif /* CONFIG_SCHED_ALT */ #else +#ifndef CONFIG_SCHED_ALT static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) { @@ -201,6 +206,7 @@ update_dl_rq_load_avg(u64 now, struct rq *rq, int running) { return 0; } +#endif static inline int update_hw_load_avg(u64 now, struct rq *rq, u64 capacity) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 6a9efb0fd..90040545f 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -5,6 +5,10 @@ #ifndef _KERNEL_SCHED_SCHED_H #define _KERNEL_SCHED_SCHED_H +#ifdef CONFIG_SCHED_ALT +#include "alt_sched.h" +#else + #include #include #include @@ -3970,4 +3974,9 @@ void sched_enq_and_set_task(struct sched_enq_and_set_ctx *ctx); #include "ext.h" +static inline int task_running_nice(struct task_struct *p) +{ + return (task_nice(p) > 0); +} +#endif /* !CONFIG_SCHED_ALT */ #endif /* _KERNEL_SCHED_SCHED_H */ diff --git a/kernel/sched/stats.c b/kernel/sched/stats.c index eb0cdcd4d..72224ecb5 100644 --- a/kernel/sched/stats.c +++ b/kernel/sched/stats.c @@ -115,8 +115,10 @@ static int show_schedstat(struct seq_file *seq, void *v) } else { struct rq *rq; #ifdef CONFIG_SMP +#ifndef CONFIG_SCHED_ALT struct sched_domain *sd; int dcount = 0; +#endif #endif cpu = (unsigned long)(v - 2); rq = cpu_rq(cpu); @@ -133,6 +135,7 @@ static int show_schedstat(struct seq_file *seq, void *v) seq_printf(seq, "\n"); #ifdef CONFIG_SMP +#ifndef CONFIG_SCHED_ALT /* domain-specific stats */ rcu_read_lock(); for_each_domain(cpu, sd) { @@ -160,6 +163,7 @@ static int show_schedstat(struct seq_file *seq, void *v) sd->ttwu_move_balance); } rcu_read_unlock(); +#endif #endif } return 0; diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h index 6ade91bce..29d421e16 100644 --- a/kernel/sched/stats.h +++ b/kernel/sched/stats.h @@ -89,6 +89,7 @@ static inline void rq_sched_info_depart (struct rq *rq, unsigned long long delt #endif /* CONFIG_SCHEDSTATS */ +#ifndef CONFIG_SCHED_ALT #ifdef CONFIG_FAIR_GROUP_SCHED struct sched_entity_stats { struct sched_entity se; @@ -105,6 +106,7 @@ __schedstats_from_se(struct sched_entity *se) #endif return &task_of(se)->stats; } +#endif /* CONFIG_SCHED_ALT */ #ifdef CONFIG_PSI void psi_task_change(struct task_struct *task, int clear, int set); diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c index 943406c4e..1bda143a5 100644 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -16,6 +16,14 @@ #include "sched.h" #include "autogroup.h" +#ifdef CONFIG_SCHED_ALT +#include "alt_core.h" + +static inline int __normal_prio(int policy, int rt_prio, int static_prio) +{ + return rt_policy(policy) ? (MAX_RT_PRIO - 1 - rt_prio) : static_prio; +} +#else /* !CONFIG_SCHED_ALT */ static inline int __normal_prio(int policy, int rt_prio, int nice) { int prio; @@ -29,6 +37,7 @@ static inline int __normal_prio(int policy, int rt_prio, int nice) return prio; } +#endif /* !CONFIG_SCHED_ALT */ /* * Calculate the expected normal priority: i.e. priority @@ -39,7 +48,11 @@ static inline int __normal_prio(int policy, int rt_prio, int nice) */ static inline int normal_prio(struct task_struct *p) { +#ifdef CONFIG_SCHED_ALT + return __normal_prio(p->policy, p->rt_priority, p->static_prio); +#else /* !CONFIG_SCHED_ALT */ return __normal_prio(p->policy, p->rt_priority, PRIO_TO_NICE(p->static_prio)); +#endif /* !CONFIG_SCHED_ALT */ } /* @@ -64,6 +77,37 @@ static int effective_prio(struct task_struct *p) void set_user_nice(struct task_struct *p, long nice) { +#ifdef CONFIG_SCHED_ALT + unsigned long flags; + struct rq *rq; + raw_spinlock_t *lock; + + if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) + return; + /* + * We have to be careful, if called from sys_setpriority(), + * the task might be in the middle of scheduling on another CPU. + */ + raw_spin_lock_irqsave(&p->pi_lock, flags); + rq = __task_access_lock(p, &lock); + + p->static_prio = NICE_TO_PRIO(nice); + /* + * The RT priorities are set via sched_setscheduler(), but we still + * allow the 'normal' nice value to be set - but as expected + * it won't have any effect on scheduling until the task is + * not SCHED_NORMAL/SCHED_BATCH: + */ + if (task_has_rt_policy(p)) + goto out_unlock; + + p->prio = effective_prio(p); + + check_task_changed(p, rq); +out_unlock: + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); +#else bool queued, running; struct rq *rq; int old_prio; @@ -112,6 +156,7 @@ void set_user_nice(struct task_struct *p, long nice) * lowered its priority, then reschedule its CPU: */ p->sched_class->prio_changed(rq, p, old_prio); +#endif /* !CONFIG_SCHED_ALT */ } EXPORT_SYMBOL(set_user_nice); @@ -190,7 +235,19 @@ SYSCALL_DEFINE1(nice, int, increment) */ int task_prio(const struct task_struct *p) { +#ifdef CONFIG_SCHED_ALT +/* + * sched policy return value kernel prio user prio/nice + * + * (BMQ)normal, batch, idle[0 ... 53] [100 ... 139] 0/[-20 ... 19]/[-7 ... 7] + * (PDS)normal, batch, idle[0 ... 39] 100 0/[-20 ... 19] + * fifo, rr [-1 ... -100] [99 ... 0] [0 ... 99] + */ + return (p->prio < MAX_RT_PRIO) ? p->prio - MAX_RT_PRIO : + task_sched_prio_normal(p, task_rq(p)); +#else return p->prio - MAX_RT_PRIO; +#endif /* !CONFIG_SCHED_ALT */ } /** @@ -300,10 +357,13 @@ static void __setscheduler_params(struct task_struct *p, p->policy = policy; +#ifndef CONFIG_SCHED_ALT if (dl_policy(policy)) { __setparam_dl(p, attr); } else if (fair_policy(policy)) { +#endif /* !CONFIG_SCHED_ALT */ p->static_prio = NICE_TO_PRIO(attr->sched_nice); +#ifndef CONFIG_SCHED_ALT if (attr->sched_runtime) { p->se.custom_slice = 1; p->se.slice = clamp_t(u64, attr->sched_runtime, @@ -322,6 +382,7 @@ static void __setscheduler_params(struct task_struct *p, /* when switching back to non-rt policy, restore timerslack */ p->timer_slack_ns = p->default_timer_slack_ns; } +#endif /* !CONFIG_SCHED_ALT */ /* * __sched_setscheduler() ensures attr->sched_priority == 0 when @@ -330,7 +391,9 @@ static void __setscheduler_params(struct task_struct *p, */ p->rt_priority = attr->sched_priority; p->normal_prio = normal_prio(p); +#ifndef CONFIG_SCHED_ALT set_load_weight(p, true); +#endif /* !CONFIG_SCHED_ALT */ } /* @@ -346,6 +409,8 @@ static bool check_same_owner(struct task_struct *p) uid_eq(cred->euid, pcred->uid)); } +#ifndef CONFIG_SCHED_ALT + #ifdef CONFIG_UCLAMP_TASK static int uclamp_validate(struct task_struct *p, @@ -459,6 +524,7 @@ static inline int uclamp_validate(struct task_struct *p, static void __setscheduler_uclamp(struct task_struct *p, const struct sched_attr *attr) { } #endif +#endif /* !CONFIG_SCHED_ALT */ /* * Allow unprivileged RT tasks to decrease priority. @@ -469,11 +535,13 @@ static int user_check_sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, int policy, int reset_on_fork) { +#ifndef CONFIG_SCHED_ALT if (fair_policy(policy)) { if (attr->sched_nice < task_nice(p) && !is_nice_reduction(p, attr->sched_nice)) goto req_priv; } +#endif /* !CONFIG_SCHED_ALT */ if (rt_policy(policy)) { unsigned long rlim_rtprio = task_rlimit(p, RLIMIT_RTPRIO); @@ -488,6 +556,7 @@ static int user_check_sched_setscheduler(struct task_struct *p, goto req_priv; } +#ifndef CONFIG_SCHED_ALT /* * Can't set/change SCHED_DEADLINE policy at all for now * (safest behavior); in the future we would like to allow @@ -505,6 +574,7 @@ static int user_check_sched_setscheduler(struct task_struct *p, if (!is_nice_reduction(p, task_nice(p))) goto req_priv; } +#endif /* !CONFIG_SCHED_ALT */ /* Can't change other user's priorities: */ if (!check_same_owner(p)) @@ -527,6 +597,158 @@ int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user, bool pi) { +#ifdef CONFIG_SCHED_ALT + const struct sched_attr dl_squash_attr = { + .size = sizeof(struct sched_attr), + .sched_policy = SCHED_FIFO, + .sched_nice = 0, + .sched_priority = 99, + }; + int oldpolicy = -1, policy = attr->sched_policy; + int retval, newprio; + struct balance_callback *head; + unsigned long flags; + struct rq *rq; + int reset_on_fork; + raw_spinlock_t *lock; + + /* The pi code expects interrupts enabled */ + BUG_ON(pi && in_interrupt()); + + /* + * Alt schedule FW supports SCHED_DEADLINE by squash it as prio 0 SCHED_FIFO + */ + if (unlikely(SCHED_DEADLINE == policy)) { + attr = &dl_squash_attr; + policy = attr->sched_policy; + } +recheck: + /* Double check policy once rq lock held */ + if (policy < 0) { + reset_on_fork = p->sched_reset_on_fork; + policy = oldpolicy = p->policy; + } else { + reset_on_fork = !!(attr->sched_flags & SCHED_RESET_ON_FORK); + + if (policy > SCHED_IDLE) + return -EINVAL; + } + + if (attr->sched_flags & ~(SCHED_FLAG_ALL)) + return -EINVAL; + + /* + * Valid priorities for SCHED_FIFO and SCHED_RR are + * 1..MAX_RT_PRIO-1, valid priority for SCHED_NORMAL and + * SCHED_BATCH and SCHED_IDLE is 0. + */ + if (attr->sched_priority < 0 || + (p->mm && attr->sched_priority > MAX_RT_PRIO - 1) || + (!p->mm && attr->sched_priority > MAX_RT_PRIO - 1)) + return -EINVAL; + if ((SCHED_RR == policy || SCHED_FIFO == policy) != + (attr->sched_priority != 0)) + return -EINVAL; + + if (user) { + retval = user_check_sched_setscheduler(p, attr, policy, reset_on_fork); + if (retval) + return retval; + + retval = security_task_setscheduler(p); + if (retval) + return retval; + } + + /* + * Make sure no PI-waiters arrive (or leave) while we are + * changing the priority of the task: + */ + raw_spin_lock_irqsave(&p->pi_lock, flags); + + /* + * To be able to change p->policy safely, task_access_lock() + * must be called. + * IF use task_access_lock() here: + * For the task p which is not running, reading rq->stop is + * racy but acceptable as ->stop doesn't change much. + * An enhancemnet can be made to read rq->stop saftly. + */ + rq = __task_access_lock(p, &lock); + + /* + * Changing the policy of the stop threads its a very bad idea + */ + if (p == rq->stop) { + retval = -EINVAL; + goto unlock; + } + + /* + * If not changing anything there's no need to proceed further: + */ + if (unlikely(policy == p->policy)) { + if (rt_policy(policy) && attr->sched_priority != p->rt_priority) + goto change; + if (!rt_policy(policy) && + NICE_TO_PRIO(attr->sched_nice) != p->static_prio) + goto change; + + p->sched_reset_on_fork = reset_on_fork; + retval = 0; + goto unlock; + } +change: + + /* Re-check policy now with rq lock held */ + if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { + policy = oldpolicy = -1; + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + goto recheck; + } + + p->sched_reset_on_fork = reset_on_fork; + + newprio = __normal_prio(policy, attr->sched_priority, NICE_TO_PRIO(attr->sched_nice)); + if (pi) { + /* + * Take priority boosted tasks into account. If the new + * effective priority is unchanged, we just store the new + * normal parameters and do not touch the scheduler class and + * the runqueue. This will be done when the task deboost + * itself. + */ + newprio = rt_effective_prio(p, newprio); + } + + if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) { + __setscheduler_params(p, attr); + __setscheduler_prio(p, newprio); + } + + check_task_changed(p, rq); + + /* Avoid rq from going away on us: */ + preempt_disable(); + head = splice_balance_callbacks(rq); + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + + if (pi) + rt_mutex_adjust_pi(p); + + /* Run balance callbacks after we've adjusted the PI chain: */ + balance_callbacks(rq, head); + preempt_enable(); + + return 0; + +unlock: + __task_access_unlock(p, lock); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + return retval; +#else /* !CONFIG_SCHED_ALT */ int oldpolicy = -1, policy = attr->sched_policy; int retval, oldprio, newprio, queued, running; const struct sched_class *prev_class, *next_class; @@ -764,6 +986,7 @@ int __sched_setscheduler(struct task_struct *p, if (cpuset_locked) cpuset_unlock(); return retval; +#endif /* !CONFIG_SCHED_ALT */ } static int _sched_setscheduler(struct task_struct *p, int policy, @@ -775,8 +998,10 @@ static int _sched_setscheduler(struct task_struct *p, int policy, .sched_nice = PRIO_TO_NICE(p->static_prio), }; +#ifndef CONFIG_SCHED_ALT if (p->se.custom_slice) attr.sched_runtime = p->se.slice; +#endif /* !CONFIG_SCHED_ALT */ /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { @@ -944,13 +1169,18 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a static void get_params(struct task_struct *p, struct sched_attr *attr) { - if (task_has_dl_policy(p)) { +#ifndef CONFIG_SCHED_ALT + if (task_has_dl_policy(p)) __getparam_dl(p, attr); - } else if (task_has_rt_policy(p)) { + else +#endif + if (task_has_rt_policy(p)) { attr->sched_priority = p->rt_priority; } else { attr->sched_nice = task_nice(p); +#ifndef CONFIG_SCHED_ALT attr->sched_runtime = p->se.slice; +#endif } } @@ -1132,6 +1362,7 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, #ifdef CONFIG_SMP int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask) { +#ifndef CONFIG_SCHED_ALT /* * If the task isn't a deadline task or admission control is * disabled then we don't care about affinity changes. @@ -1148,6 +1379,7 @@ int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask) guard(rcu)(); if (!cpumask_subset(task_rq(p)->rd->span, mask)) return -EBUSY; +#endif return 0; } @@ -1172,9 +1404,11 @@ int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx) ctx->new_mask = new_mask; ctx->flags |= SCA_CHECK; +#ifndef CONFIG_SCHED_ALT retval = dl_task_check_affinity(p, new_mask); if (retval) goto out_free_new_mask; +#endif retval = __set_cpus_allowed_ptr(p, ctx); if (retval) @@ -1354,13 +1588,34 @@ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, static void do_sched_yield(void) { - struct rq_flags rf; struct rq *rq; + struct rq_flags rf; + +#ifdef CONFIG_SCHED_ALT + struct task_struct *p; + + if (!sched_yield_type) + return; rq = this_rq_lock_irq(&rf); + schedstat_inc(rq->yld_count); + + p = current; + if (rt_task(p)) { + if (task_on_rq_queued(p)) + requeue_task(p, rq); + } else if (rq->nr_running > 1) { + do_sched_yield_type_1(p, rq); + if (task_on_rq_queued(p)) + requeue_task(p, rq); + } +#else /* !CONFIG_SCHED_ALT */ + rq = this_rq_lock_irq(&rf); + schedstat_inc(rq->yld_count); current->sched_class->yield_task(rq); +#endif /* !CONFIG_SCHED_ALT */ preempt_disable(); rq_unlock_irq(rq, &rf); @@ -1429,6 +1684,9 @@ EXPORT_SYMBOL(yield); */ int __sched yield_to(struct task_struct *p, bool preempt) { +#ifdef CONFIG_SCHED_ALT + return 0; +#else /* !CONFIG_SCHED_ALT */ struct task_struct *curr = current; struct rq *rq, *p_rq; int yielded = 0; @@ -1474,6 +1732,7 @@ int __sched yield_to(struct task_struct *p, bool preempt) schedule(); return yielded; +#endif /* !CONFIG_SCHED_ALT */ } EXPORT_SYMBOL_GPL(yield_to); @@ -1494,7 +1753,9 @@ SYSCALL_DEFINE1(sched_get_priority_max, int, policy) case SCHED_RR: ret = MAX_RT_PRIO-1; break; +#ifndef CONFIG_SCHED_ALT case SCHED_DEADLINE: +#endif case SCHED_NORMAL: case SCHED_BATCH: case SCHED_IDLE: @@ -1522,7 +1783,9 @@ SYSCALL_DEFINE1(sched_get_priority_min, int, policy) case SCHED_RR: ret = 1; break; +#ifndef CONFIG_SCHED_ALT case SCHED_DEADLINE: +#endif case SCHED_NORMAL: case SCHED_BATCH: case SCHED_IDLE: @@ -1534,7 +1797,9 @@ SYSCALL_DEFINE1(sched_get_priority_min, int, policy) static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) { +#ifndef CONFIG_SCHED_ALT unsigned int time_slice = 0; +#endif int retval; if (pid < 0) @@ -1549,6 +1814,7 @@ static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) if (retval) return retval; +#ifndef CONFIG_SCHED_ALT scoped_guard (task_rq_lock, p) { struct rq *rq = scope.rq; if (p->sched_class->get_rr_interval) @@ -1557,6 +1823,13 @@ static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) } jiffies_to_timespec64(time_slice, t); +#else + } + + alt_sched_debug(); + + *t = ns_to_timespec64(sysctl_sched_base_slice); +#endif /* !CONFIG_SCHED_ALT */ return 0; } diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 59b8157cb..2151ddde2 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -3,6 +3,7 @@ * Scheduler topology setup/handling methods */ +#ifndef CONFIG_SCHED_ALT #include DEFINE_MUTEX(sched_domains_mutex); @@ -1446,8 +1447,10 @@ static void asym_cpu_capacity_scan(void) */ static int default_relax_domain_level = -1; +#endif /* CONFIG_SCHED_ALT */ int sched_domain_level_max; +#ifndef CONFIG_SCHED_ALT static int __init setup_relax_domain_level(char *str) { if (kstrtoint(str, 0, &default_relax_domain_level)) @@ -1682,6 +1685,7 @@ sd_init(struct sched_domain_topology_level *tl, return sd; } +#endif /* CONFIG_SCHED_ALT */ /* * Topology list, bottom-up. @@ -1718,6 +1722,7 @@ void __init set_sched_topology(struct sched_domain_topology_level *tl) sched_domain_topology_saved = NULL; } +#ifndef CONFIG_SCHED_ALT #ifdef CONFIG_NUMA static const struct cpumask *sd_numa_mask(int cpu) @@ -2784,3 +2789,28 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], partition_sched_domains_locked(ndoms_new, doms_new, dattr_new); mutex_unlock(&sched_domains_mutex); } +#else /* CONFIG_SCHED_ALT */ +DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity); + +void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], + struct sched_domain_attr *dattr_new) +{} + +#ifdef CONFIG_NUMA +int sched_numa_find_closest(const struct cpumask *cpus, int cpu) +{ + return best_mask_cpu(cpu, cpus); +} + +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + return cpumask_nth(cpu, cpus); +} + +const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops) +{ + return ERR_PTR(-EOPNOTSUPP); +} +EXPORT_SYMBOL_GPL(sched_numa_hop_mask); +#endif /* CONFIG_NUMA */ +#endif diff --git a/kernel/sysctl.c b/kernel/sysctl.c index de4ddf79f..743d96f31 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -95,6 +95,10 @@ EXPORT_SYMBOL_GPL(sysctl_long_vals); /* Constants used for minimum and maximum */ +#ifdef CONFIG_SCHED_ALT +extern int sched_yield_type; +#endif + #ifdef CONFIG_PERF_EVENTS static const int six_hundred_forty_kb = 640 * 1024; #endif @@ -1918,6 +1922,17 @@ static struct ctl_table kern_table[] = { .proc_handler = proc_dointvec, }, #endif +#ifdef CONFIG_SCHED_ALT + { + .procname = "yield_type", + .data = &sched_yield_type, + .maxlen = sizeof (int), + .mode = 0644, + .proc_handler = &proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_TWO, + }, +#endif #if defined(CONFIG_S390) && defined(CONFIG_SMP) { .procname = "spin_retry", diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 50e8d04ab..0a761f9cd 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -223,7 +223,7 @@ static void task_sample_cputime(struct task_struct *p, u64 *samples) u64 stime, utime; task_cputime(p, &utime, &stime); - store_samples(samples, stime, utime, p->se.sum_exec_runtime); + store_samples(samples, stime, utime, tsk_seruntime(p)); } static void proc_sample_cputime_atomic(struct task_cputime_atomic *at, @@ -835,6 +835,7 @@ static void collect_posix_cputimers(struct posix_cputimers *pct, u64 *samples, } } +#ifndef CONFIG_SCHED_ALT static inline void check_dl_overrun(struct task_struct *tsk) { if (tsk->dl.dl_overrun) { @@ -842,6 +843,7 @@ static inline void check_dl_overrun(struct task_struct *tsk) send_signal_locked(SIGXCPU, SEND_SIG_PRIV, tsk, PIDTYPE_TGID); } } +#endif static bool check_rlimit(u64 time, u64 limit, int signo, bool rt, bool hard) { @@ -869,8 +871,10 @@ static void check_thread_timers(struct task_struct *tsk, u64 samples[CPUCLOCK_MAX]; unsigned long soft; +#ifndef CONFIG_SCHED_ALT if (dl_task(tsk)) check_dl_overrun(tsk); +#endif if (expiry_cache_is_inactive(pct)) return; @@ -884,7 +888,7 @@ static void check_thread_timers(struct task_struct *tsk, soft = task_rlimit(tsk, RLIMIT_RTTIME); if (soft != RLIM_INFINITY) { /* Task RT timeout is accounted in jiffies. RTTIME is usec */ - unsigned long rttime = tsk->rt.timeout * (USEC_PER_SEC / HZ); + unsigned long rttime = tsk_rttimeout(tsk) * (USEC_PER_SEC / HZ); unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME); /* At the hard limit, send SIGKILL. No further action. */ @@ -1120,8 +1124,10 @@ static inline bool fastpath_timer_check(struct task_struct *tsk) return true; } +#ifndef CONFIG_SCHED_ALT if (dl_task(tsk) && tsk->dl.dl_overrun) return true; +#endif return false; } diff --git a/kernel/time/timer.c b/kernel/time/timer.c index a5860bf6d..77197b887 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -2499,7 +2499,11 @@ static void run_local_timers(void) */ if (time_after_eq(jiffies, READ_ONCE(base->next_expiry)) || (i == BASE_DEF && tmigr_requires_handle_remote())) { +#ifdef CONFIG_SCHED_BMQ + __raise_softirq_irqoff(TIMER_SOFTIRQ); +#else raise_timer_softirq(TIMER_SOFTIRQ); +#endif return; } } diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 23cbc24ed..3df4fcfd3 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1670,6 +1670,9 @@ static void osnoise_sleep(bool skip_period) */ static inline int osnoise_migration_pending(void) { +#ifdef CONFIG_SCHED_ALT + return 0; +#else if (!current->migration_pending) return 0; @@ -1691,6 +1694,7 @@ static inline int osnoise_migration_pending(void) mutex_unlock(&interface_lock); return 1; +#endif } /* diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 38b575479..cab7819b2 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -1420,10 +1420,15 @@ static int trace_wakeup_test_thread(void *data) { /* Make this a -deadline thread */ static const struct sched_attr attr = { +#ifdef CONFIG_SCHED_ALT + /* No deadline on BMQ/PDS, use RR */ + .sched_policy = SCHED_RR, +#else .sched_policy = SCHED_DEADLINE, .sched_runtime = 100000ULL, .sched_deadline = 10000000ULL, .sched_period = 10000000ULL +#endif }; struct wakeup_test_data *x = data; diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 218f8c138..9dceff5ee 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1247,6 +1247,7 @@ static bool kick_pool(struct worker_pool *pool) p = worker->task; +#ifndef CONFIG_SCHED_ALT #ifdef CONFIG_SMP /* * Idle @worker is about to execute @work and waking up provides an @@ -1276,6 +1277,8 @@ static bool kick_pool(struct worker_pool *pool) } } #endif +#endif /* !CONFIG_SCHED_ALT */ + wake_up_process(p); return true; } @@ -1404,7 +1407,11 @@ void wq_worker_running(struct task_struct *task) * CPU intensive auto-detection cares about how long a work item hogged * CPU without sleeping. Reset the starting timestamp on wakeup. */ +#ifdef CONFIG_SCHED_ALT + worker->current_at = worker->task->sched_time; +#else worker->current_at = worker->task->se.sum_exec_runtime; +#endif WRITE_ONCE(worker->sleeping, 0); } @@ -1489,7 +1496,11 @@ void wq_worker_tick(struct task_struct *task) * We probably want to make this prettier in the future. */ if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) || +#ifdef CONFIG_SCHED_ALT + worker->task->sched_time - worker->current_at < +#else worker->task->se.sum_exec_runtime - worker->current_at < +#endif wq_cpu_intensive_thresh_us * NSEC_PER_USEC) return; @@ -3164,7 +3175,11 @@ __acquires(&pool->lock) worker->current_func = work->func; worker->current_pwq = pwq; if (worker->task) +#ifdef CONFIG_SCHED_ALT + worker->current_at = worker->task->sched_time; +#else worker->current_at = worker->task->se.sum_exec_runtime; +#endif work_data = *work_data_bits(work); worker->current_color = get_work_color(work_data); -- 2.48.1