| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * kernel/sched/core.c |
| * |
| * Core kernel scheduler code and related syscalls |
| * |
| * Copyright (C) 1991-2002 Linus Torvalds |
| */ |
| #include "sched.h" |
| |
| #include <linux/nospec.h> |
| |
| #include <linux/kcov.h> |
| |
| #include <asm/switch_to.h> |
| #include <asm/tlb.h> |
| |
| #include "../workqueue_internal.h" |
| #include "../../fs/io-wq.h" |
| #include "../smpboot.h" |
| |
| #include "pelt.h" |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/sched.h> |
| |
| /* |
| * 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_cfs_tp); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp); |
| |
| DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); |
| |
| #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_JUMP_LABEL) |
| /* |
| * Debugging: various feature bits |
| * |
| * If SCHED_DEBUG is disabled, each compilation unit has its own copy of |
| * sysctl_sched_features, defined in sched.h, to allow constants propagation |
| * at compile time and compiler optimization based on features default. |
| */ |
| #define SCHED_FEAT(name, enabled) \ |
| (1UL << __SCHED_FEAT_##name) * enabled | |
| const_debug unsigned int sysctl_sched_features = |
| #include "features.h" |
| 0; |
| #undef SCHED_FEAT |
| #endif |
| |
| /* |
| * Number of tasks to iterate in a single balance run. |
| * Limited because this is done with IRQs disabled. |
| */ |
| const_debug unsigned int sysctl_sched_nr_migrate = 32; |
| |
| /* |
| * period over which we measure -rt task CPU usage in us. |
| * default: 1s |
| */ |
| unsigned int sysctl_sched_rt_period = 1000000; |
| |
| __read_mostly int scheduler_running; |
| |
| /* |
| * part of the period that we allow rt tasks to run in us. |
| * default: 0.95s |
| */ |
| int sysctl_sched_rt_runtime = 950000; |
| |
| /* |
| * __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))) { |
| rq_pin_lock(rq, rf); |
| 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))) { |
| rq_pin_lock(rq, rf); |
| 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(); |
| } |
| } |
| |
| /* |
| * 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; |
| #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) && sched_feat(NONTASK_CAPACITY)) |
| update_irq_load_avg(rq, irq_delta + steal); |
| #endif |
| update_rq_clock_pelt(rq, delta); |
| } |
| |
| void update_rq_clock(struct rq *rq) |
| { |
| s64 delta; |
| |
| lockdep_assert_held(&rq->lock); |
| |
| if (rq->clock_update_flags & RQCF_ACT_SKIP) |
| return; |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| if (sched_feat(WARN_DOUBLE_CLOCK)) |
| SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); |
| rq->clock_update_flags |= RQCF_UPDATED; |
| #endif |
| |
| delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; |
| if (delta < 0) |
| return; |
| rq->clock += delta; |
| update_rq_clock_task(rq, delta); |
| } |
| |
| |
| #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); |
| struct rq_flags rf; |
| |
| WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); |
| |
| rq_lock(rq, &rf); |
| update_rq_clock(rq); |
| rq->curr->sched_class->task_tick(rq, rq->curr, 1); |
| rq_unlock(rq, &rf); |
| |
| return HRTIMER_NORESTART; |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| static void __hrtick_restart(struct rq *rq) |
| { |
| struct hrtimer *timer = &rq->hrtick_timer; |
| |
| hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD); |
| } |
| |
| /* |
| * called from hardirq (IPI) context |
| */ |
| static void __hrtick_start(void *arg) |
| { |
| struct rq *rq = arg; |
| struct rq_flags rf; |
| |
| rq_lock(rq, &rf); |
| __hrtick_restart(rq); |
| rq->hrtick_csd_pending = 0; |
| rq_unlock(rq, &rf); |
| } |
| |
| /* |
| * Called to set the hrtick timer state. |
| * |
| * called with rq->lock held and irqs disabled |
| */ |
| void hrtick_start(struct rq *rq, u64 delay) |
| { |
| struct hrtimer *timer = &rq->hrtick_timer; |
| ktime_t time; |
| 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); |
| time = ktime_add_ns(timer->base->get_time(), delta); |
| |
| hrtimer_set_expires(timer, time); |
| |
| if (rq == this_rq()) { |
| __hrtick_restart(rq); |
| } else if (!rq->hrtick_csd_pending) { |
| smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); |
| rq->hrtick_csd_pending = 1; |
| } |
| } |
| |
| #else |
| /* |
| * Called to set the hrtick timer state. |
| * |
| * called with rq->lock held and irqs disabled |
| */ |
| 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 |
| rq->hrtick_csd_pending = 0; |
| |
| rq->hrtick_csd.flags = 0; |
| rq->hrtick_csd.func = __hrtick_start; |
| rq->hrtick_csd.info = rq; |
| #endif |
| |
| hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); |
| rq->hrtick_timer.function = hrtick; |
| } |
| #else /* CONFIG_SCHED_HRTICK */ |
| static inline void hrtick_clear(struct rq *rq) |
| { |
| } |
| |
| static inline void hrtick_rq_init(struct rq *rq) |
| { |
| } |
| #endif /* CONFIG_SCHED_HRTICK */ |
| |
| /* |
| * 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) _old, _val = *_ptr; \ |
| \ |
| for (;;) { \ |
| _old = cmpxchg(_ptr, _val, _val | _mask); \ |
| if (_old == _val) \ |
| break; \ |
| _val = _old; \ |
| } \ |
| _old; \ |
| }) |
| |
| #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 bool set_nr_and_not_polling(struct task_struct *p) |
| { |
| struct thread_info *ti = task_thread_info(p); |
| return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _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) old, val = READ_ONCE(ti->flags); |
| |
| for (;;) { |
| if (!(val & _TIF_POLLING_NRFLAG)) |
| return false; |
| if (val & _TIF_NEED_RESCHED) |
| return true; |
| old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); |
| if (old == val) |
| break; |
| val = old; |
| } |
| return true; |
| } |
| |
| #else |
| static bool set_nr_and_not_polling(struct task_struct *p) |
| { |
| set_tsk_need_resched(p); |
| return true; |
| } |
| |
| #ifdef CONFIG_SMP |
| static 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 |
| * its 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); |
| BUG_ON(!task); |
| /* 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. |
| */ |
| void resched_curr(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| int cpu; |
| |
| lockdep_assert_held(&rq->lock); |
| |
| if (test_tsk_need_resched(curr)) |
| return; |
| |
| cpu = cpu_of(rq); |
| |
| if (cpu == smp_processor_id()) { |
| set_tsk_need_resched(curr); |
| set_preempt_need_resched(); |
| return; |
| } |
| |
| if (set_nr_and_not_polling(curr)) |
| smp_send_reschedule(cpu); |
| else |
| trace_sched_wake_idle_without_ipi(cpu); |
| } |
| |
| 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(rq); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| #ifdef CONFIG_SMP |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * 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 uptodate wrt jiffies etc). |
| */ |
| int get_nohz_timer_target(void) |
| { |
| int i, cpu = smp_processor_id(); |
| struct sched_domain *sd; |
| |
| if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
| return cpu; |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, sd) { |
| for_each_cpu(i, sched_domain_span(sd)) { |
| if (cpu == i) |
| continue; |
| |
| if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) { |
| cpu = i; |
| goto unlock; |
| } |
| } |
| } |
| |
| if (!housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
| cpu = housekeeping_any_cpu(HK_FLAG_TIMER); |
| unlock: |
| rcu_read_unlock(); |
| 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 void wake_up_idle_cpu(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| if (cpu == smp_processor_id()) |
| return; |
| |
| if (set_nr_and_not_polling(rq->idle)) |
| smp_send_reschedule(cpu); |
| else |
| trace_sched_wake_idle_without_ipi(cpu); |
| } |
| |
| static 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; |
| } |
| |
| /* |
| * Wake up the specified CPU. If the CPU is going offline, it is the |
| * caller's responsibility to deal with the lost wakeup, for example, |
| * by hooking into the CPU_DEAD notifier like timers and hrtimers do. |
| */ |
| void wake_up_nohz_cpu(int cpu) |
| { |
| if (!wake_up_full_nohz_cpu(cpu)) |
| wake_up_idle_cpu(cpu); |
| } |
| |
| static inline bool got_nohz_idle_kick(void) |
| { |
| int cpu = smp_processor_id(); |
| |
| if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK)) |
| return false; |
| |
| if (idle_cpu(cpu) && !need_resched()) |
| return true; |
| |
| /* |
| * We can't run Idle Load Balance on this CPU for this time so we |
| * cancel it and clear NOHZ_BALANCE_KICK |
| */ |
| atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu)); |
| return false; |
| } |
| |
| #else /* CONFIG_NO_HZ_COMMON */ |
| |
| static inline bool got_nohz_idle_kick(void) |
| { |
| return false; |
| } |
| |
| #endif /* CONFIG_NO_HZ_COMMON */ |
| |
| #ifdef CONFIG_NO_HZ_FULL |
| bool sched_can_stop_tick(struct rq *rq) |
| { |
| int fifo_nr_running; |
| |
| /* Deadline tasks, even if single, need the tick */ |
| if (rq->dl.dl_nr_running) |
| return false; |
| |
| /* |
| * If there are more than one RR tasks, we need the tick to effect the |
| * actual RR behaviour. |
| */ |
| if (rq->rt.rr_nr_running) { |
| if (rq->rt.rr_nr_running == 1) |
| return true; |
| else |
| return false; |
| } |
| |
| /* |
| * If there's no RR tasks, but FIFO tasks, we can skip the tick, no |
| * forced preemption between FIFO tasks. |
| */ |
| fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; |
| if (fifo_nr_running) |
| return true; |
| |
| /* |
| * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; |
| * if there's more than one we need the tick for involuntary |
| * preemption. |
| */ |
| if (rq->nr_running > 1) |
| return false; |
| |
| return true; |
| } |
| #endif /* CONFIG_NO_HZ_FULL */ |
| #endif /* CONFIG_SMP */ |
| |
| #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ |
| (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) |
| /* |
| * Iterate task_group tree rooted at *from, calling @down when first entering a |
| * node and @up when leaving it for the final time. |
| * |
| * Caller must hold rcu_lock or sufficient equivalent. |
| */ |
| int walk_tg_tree_from(struct task_group *from, |
| tg_visitor down, tg_visitor up, void *data) |
| { |
| struct task_group *parent, *child; |
| int ret; |
| |
| parent = from; |
| |
| down: |
| ret = (*down)(parent, data); |
| if (ret) |
| goto out; |
| list_for_each_entry_rcu(child, &parent->children, siblings) { |
| parent = child; |
| goto down; |
| |
| up: |
| continue; |
| } |
| ret = (*up)(parent, data); |
| if (ret || parent == from) |
| goto out; |
| |
| child = parent; |
| parent = parent->parent; |
| if (parent) |
| goto up; |
| out: |
| return ret; |
| } |
| |
| int tg_nop(struct task_group *tg, void *data) |
| { |
| return 0; |
| } |
| #endif |
| |
| static void set_load_weight(struct task_struct *p, bool update_load) |
| { |
| int prio = p->static_prio - MAX_RT_PRIO; |
| struct load_weight *load = &p->se.load; |
| |
| /* |
| * SCHED_IDLE tasks get minimal weight: |
| */ |
| if (task_has_idle_policy(p)) { |
| load->weight = scale_load(WEIGHT_IDLEPRIO); |
| load->inv_weight = WMULT_IDLEPRIO; |
| p->se.runnable_weight = load->weight; |
| return; |
| } |
| |
| /* |
| * SCHED_OTHER tasks have to update their load when changing their |
| * weight |
| */ |
| if (update_load && p->sched_class == &fair_sched_class) { |
| reweight_task(p, prio); |
| } else { |
| load->weight = scale_load(sched_prio_to_weight[prio]); |
| load->inv_weight = sched_prio_to_wmult[prio]; |
| p->se.runnable_weight = load->weight; |
| } |
| } |
| |
| #ifdef CONFIG_UCLAMP_TASK |
| /* |
| * Serializes updates of utilization clamp values |
| * |
| * The (slow-path) user-space triggers utilization clamp value updates which |
| * can require updates on (fast-path) scheduler's data structures used to |
| * support enqueue/dequeue operations. |
| * While the per-CPU rq lock protects fast-path update operations, user-space |
| * requests are serialized using a mutex to reduce the risk of conflicting |
| * updates or API abuses. |
| */ |
| static DEFINE_MUTEX(uclamp_mutex); |
| |
| /* Max allowed minimum utilization */ |
| unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE; |
| |
| /* Max allowed maximum utilization */ |
| unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE; |
| |
| /* All clamps are required to be less or equal than these values */ |
| static struct uclamp_se uclamp_default[UCLAMP_CNT]; |
| |
| /* Integer rounded range for each bucket */ |
| #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS) |
| |
| #define for_each_clamp_id(clamp_id) \ |
| for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++) |
| |
| static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) |
| { |
| return clamp_value / UCLAMP_BUCKET_DELTA; |
| } |
| |
| static inline unsigned int uclamp_bucket_base_value(unsigned int clamp_value) |
| { |
| return UCLAMP_BUCKET_DELTA * uclamp_bucket_id(clamp_value); |
| } |
| |
| static inline unsigned int uclamp_none(enum uclamp_id clamp_id) |
| { |
| if (clamp_id == UCLAMP_MIN) |
| return 0; |
| return SCHED_CAPACITY_SCALE; |
| } |
| |
| static inline void uclamp_se_set(struct uclamp_se *uc_se, |
| unsigned int value, bool user_defined) |
| { |
| uc_se->value = value; |
| uc_se->bucket_id = uclamp_bucket_id(value); |
| uc_se->user_defined = user_defined; |
| } |
| |
| static inline unsigned int |
| uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id, |
| unsigned int clamp_value) |
| { |
| /* |
| * Avoid blocked utilization pushing up the frequency when we go |
| * idle (which drops the max-clamp) by retaining the last known |
| * max-clamp. |
| */ |
| if (clamp_id == UCLAMP_MAX) { |
| rq->uclamp_flags |= UCLAMP_FLAG_IDLE; |
| return clamp_value; |
| } |
| |
| return uclamp_none(UCLAMP_MIN); |
| } |
| |
| static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id, |
| unsigned int clamp_value) |
| { |
| /* Reset max-clamp retention only on idle exit */ |
| if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE)) |
| return; |
| |
| WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value); |
| } |
| |
| static inline |
| unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id, |
| unsigned int clamp_value) |
| { |
| struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket; |
| int bucket_id = UCLAMP_BUCKETS - 1; |
| |
| /* |
| * Since both min and max clamps are max aggregated, find the |
| * top most bucket with tasks in. |
| */ |
| for ( ; bucket_id >= 0; bucket_id--) { |
| if (!bucket[bucket_id].tasks) |
| continue; |
| return bucket[bucket_id].value; |
| } |
| |
| /* No tasks -- default clamp values */ |
| return uclamp_idle_value(rq, clamp_id, clamp_value); |
| } |
| |
| static inline struct uclamp_se |
| uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id) |
| { |
| struct uclamp_se uc_req = p->uclamp_req[clamp_id]; |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| struct uclamp_se uc_max; |
| |
| /* |
| * Tasks in autogroups or root task group will be |
| * restricted by system defaults. |
| */ |
| if (task_group_is_autogroup(task_group(p))) |
| return uc_req; |
| if (task_group(p) == &root_task_group) |
| return uc_req; |
| |
| uc_max = task_group(p)->uclamp[clamp_id]; |
| if (uc_req.value > uc_max.value || !uc_req.user_defined) |
| return uc_max; |
| #endif |
| |
| return uc_req; |
| } |
| |
| /* |
| * The effective clamp bucket index of a task depends on, by increasing |
| * priority: |
| * - the task specific clamp value, when explicitly requested from userspace |
| * - the task group effective clamp value, for tasks not either in the root |
| * group or in an autogroup |
| * - the system default clamp value, defined by the sysadmin |
| */ |
| static inline struct uclamp_se |
| uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id) |
| { |
| struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id); |
| struct uclamp_se uc_max = uclamp_default[clamp_id]; |
| |
| /* System default restrictions always apply */ |
| if (unlikely(uc_req.value > uc_max.value)) |
| return uc_max; |
| |
| return uc_req; |
| } |
| |
| unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id) |
| { |
| struct uclamp_se uc_eff; |
| |
| /* Task currently refcounted: use back-annotated (effective) value */ |
| if (p->uclamp[clamp_id].active) |
| return (unsigned long)p->uclamp[clamp_id].value; |
| |
| uc_eff = uclamp_eff_get(p, clamp_id); |
| |
| return (unsigned long)uc_eff.value; |
| } |
| |
| /* |
| * When a task is enqueued on a rq, the clamp bucket currently defined by the |
| * task's uclamp::bucket_id is refcounted on that rq. This also immediately |
| * updates the rq's clamp value if required. |
| * |
| * Tasks can have a task-specific value requested from user-space, track |
| * within each bucket the maximum value for tasks refcounted in it. |
| * This "local max aggregation" allows to track the exact "requested" value |
| * for each bucket when all its RUNNABLE tasks require the same clamp. |
| */ |
| static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p, |
| enum uclamp_id clamp_id) |
| { |
| struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id]; |
| struct uclamp_se *uc_se = &p->uclamp[clamp_id]; |
| struct uclamp_bucket *bucket; |
| |
| lockdep_assert_held(&rq->lock); |
| |
| /* Update task effective clamp */ |
| p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id); |
| |
| bucket = &uc_rq->bucket[uc_se->bucket_id]; |
| bucket->tasks++; |
| uc_se->active = true; |
| |
| uclamp_idle_reset(rq, clamp_id, uc_se->value); |
| |
| /* |
| * Local max aggregation: rq buckets always track the max |
| * "requested" clamp value of its RUNNABLE tasks. |
| */ |
| if (bucket->tasks == 1 || uc_se->value > bucket->value) |
| bucket->value = uc_se->value; |
| |
| if (uc_se->value > READ_ONCE(uc_rq->value)) |
| WRITE_ONCE(uc_rq->value, uc_se->value); |
| } |
| |
| /* |
| * When a task is dequeued from a rq, the clamp bucket refcounted by the task |
| * is released. If this is the last task reference counting the rq's max |
| * active clamp value, then the rq's clamp value is updated. |
| * |
| * Both refcounted tasks and rq's cached clamp values are expected to be |
| * always valid. If it's detected they are not, as defensive programming, |
| * enforce the expected state and warn. |
| */ |
| static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, |
| enum uclamp_id clamp_id) |
| { |
| struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id]; |
| struct uclamp_se *uc_se = &p->uclamp[clamp_id]; |
| struct uclamp_bucket *bucket; |
| unsigned int bkt_clamp; |
| unsigned int rq_clamp; |
| |
| lockdep_assert_held(&rq->lock); |
| |
| bucket = &uc_rq->bucket[uc_se->bucket_id]; |
| SCHED_WARN_ON(!bucket->tasks); |
| if (likely(bucket->tasks)) |
| bucket->tasks--; |
| uc_se->active = false; |
| |
| /* |
| * Keep "local max aggregation" simple and accept to (possibly) |
| * overboost some RUNNABLE tasks in the same bucket. |
| * The rq clamp bucket value is reset to its base value whenever |
| * there are no more RUNNABLE tasks refcounting it. |
| */ |
| if (likely(bucket->tasks)) |
| return; |
| |
| rq_clamp = READ_ONCE(uc_rq->value); |
| /* |
| * Defensive programming: this should never happen. If it happens, |
| * e.g. due to future modification, warn and fixup the expected value. |
| */ |
| SCHED_WARN_ON(bucket->value > rq_clamp); |
| if (bucket->value >= rq_clamp) { |
| bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value); |
| WRITE_ONCE(uc_rq->value, bkt_clamp); |
| } |
| } |
| |
| static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) |
| { |
| enum uclamp_id clamp_id; |
| |
| if (unlikely(!p->sched_class->uclamp_enabled)) |
| return; |
| |
| for_each_clamp_id(clamp_id) |
| uclamp_rq_inc_id(rq, p, clamp_id); |
| |
| /* Reset clamp idle holding when there is one RUNNABLE task */ |
| if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) |
| rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE; |
| } |
| |
| static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) |
| { |
| enum uclamp_id clamp_id; |
| |
| if (unlikely(!p->sched_class->uclamp_enabled)) |
| return; |
| |
| for_each_clamp_id(clamp_id) |
| uclamp_rq_dec_id(rq, p, clamp_id); |
| } |
| |
| static inline void |
| uclamp_update_active(struct task_struct *p, enum uclamp_id clamp_id) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| /* |
| * Lock the task and the rq where the task is (or was) queued. |
| * |
| * We might lock the (previous) rq of a !RUNNABLE task, but that's the |
| * price to pay to safely serialize util_{min,max} updates with |
| * enqueues, dequeues and migration operations. |
| * This is the same locking schema used by __set_cpus_allowed_ptr(). |
| */ |
| rq = task_rq_lock(p, &rf); |
| |
| /* |
| * Setting the clamp bucket is serialized by task_rq_lock(). |
| * If the task is not yet RUNNABLE and its task_struct is not |
| * affecting a valid clamp bucket, the next time it's enqueued, |
| * it will already see the updated clamp bucket value. |
| */ |
| if (p->uclamp[clamp_id].active) { |
| uclamp_rq_dec_id(rq, p, clamp_id); |
| uclamp_rq_inc_id(rq, p, clamp_id); |
| } |
| |
| task_rq_unlock(rq, p, &rf); |
| } |
| |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| static inline void |
| uclamp_update_active_tasks(struct cgroup_subsys_state *css, |
| unsigned int clamps) |
| { |
| enum uclamp_id clamp_id; |
| struct css_task_iter it; |
| struct task_struct *p; |
| |
| css_task_iter_start(css, 0, &it); |
| while ((p = css_task_iter_next(&it))) { |
| for_each_clamp_id(clamp_id) { |
| if ((0x1 << clamp_id) & clamps) |
| uclamp_update_active(p, clamp_id); |
| } |
| } |
| css_task_iter_end(&it); |
| } |
| |
| static void cpu_util_update_eff(struct cgroup_subsys_state *css); |
| static void uclamp_update_root_tg(void) |
| { |
| struct task_group *tg = &root_task_group; |
| |
| uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN], |
| sysctl_sched_uclamp_util_min, false); |
| uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX], |
| sysctl_sched_uclamp_util_max, false); |
| |
| rcu_read_lock(); |
| cpu_util_update_eff(&root_task_group.css); |
| rcu_read_unlock(); |
| } |
| #else |
| static void uclamp_update_root_tg(void) { } |
| #endif |
| |
| int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, |
| loff_t *ppos) |
| { |
| bool update_root_tg = false; |
| int old_min, old_max; |
| int result; |
| |
| mutex_lock(&uclamp_mutex); |
| old_min = sysctl_sched_uclamp_util_min; |
| old_max = sysctl_sched_uclamp_util_max; |
| |
| result = proc_dointvec(table, write, buffer, lenp, ppos); |
| if (result) |
| goto undo; |
| if (!write) |
| goto done; |
| |
| if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max || |
| sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE) { |
| result = -EINVAL; |
| goto undo; |
| } |
| |
| if (old_min != sysctl_sched_uclamp_util_min) { |
| uclamp_se_set(&uclamp_default[UCLAMP_MIN], |
| sysctl_sched_uclamp_util_min, false); |
| update_root_tg = true; |
| } |
| if (old_max != sysctl_sched_uclamp_util_max) { |
| uclamp_se_set(&uclamp_default[UCLAMP_MAX], |
| sysctl_sched_uclamp_util_max, false); |
| update_root_tg = true; |
| } |
| |
| if (update_root_tg) |
| uclamp_update_root_tg(); |
| |
| /* |
| * We update all RUNNABLE tasks only when task groups are in use. |
| * Otherwise, keep it simple and do just a lazy update at each next |
| * task enqueue time. |
| */ |
| |
| goto done; |
| |
| undo: |
| sysctl_sched_uclamp_util_min = old_min; |
| sysctl_sched_uclamp_util_max = old_max; |
| done: |
| mutex_unlock(&uclamp_mutex); |
| |
| return result; |
| } |
| |
| static int uclamp_validate(struct task_struct *p, |
| const struct sched_attr *attr) |
| { |
| unsigned int lower_bound = p->uclamp_req[UCLAMP_MIN].value; |
| unsigned int upper_bound = p->uclamp_req[UCLAMP_MAX].value; |
| |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) |
| lower_bound = attr->sched_util_min; |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) |
| upper_bound = attr->sched_util_max; |
| |
| if (lower_bound > upper_bound) |
| return -EINVAL; |
| if (upper_bound > SCHED_CAPACITY_SCALE) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| static void __setscheduler_uclamp(struct task_struct *p, |
| const struct sched_attr *attr) |
| { |
| enum uclamp_id clamp_id; |
| |
| /* |
| * On scheduling class change, reset to default clamps for tasks |
| * without a task-specific value. |
| */ |
| for_each_clamp_id(clamp_id) { |
| struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; |
| unsigned int clamp_value = uclamp_none(clamp_id); |
| |
| /* Keep using defined clamps across class changes */ |
| if (uc_se->user_defined) |
| continue; |
| |
| /* By default, RT tasks always get 100% boost */ |
| if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) |
| clamp_value = uclamp_none(UCLAMP_MAX); |
| |
| uclamp_se_set(uc_se, clamp_value, false); |
| } |
| |
| if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) |
| return; |
| |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) { |
| uclamp_se_set(&p->uclamp_req[UCLAMP_MIN], |
| attr->sched_util_min, true); |
| } |
| |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { |
| uclamp_se_set(&p->uclamp_req[UCLAMP_MAX], |
| attr->sched_util_max, true); |
| } |
| } |
| |
| static void uclamp_fork(struct task_struct *p) |
| { |
| enum uclamp_id clamp_id; |
| |
| for_each_clamp_id(clamp_id) |
| p->uclamp[clamp_id].active = false; |
| |
| if (likely(!p->sched_reset_on_fork)) |
| return; |
| |
| for_each_clamp_id(clamp_id) { |
| unsigned int clamp_value = uclamp_none(clamp_id); |
| |
| /* By default, RT tasks always get 100% boost */ |
| if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) |
| clamp_value = uclamp_none(UCLAMP_MAX); |
| |
| uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); |
| } |
| } |
| |
| static void __init init_uclamp(void) |
| { |
| struct uclamp_se uc_max = {}; |
| enum uclamp_id clamp_id; |
| int cpu; |
| |
| mutex_init(&uclamp_mutex); |
| |
| for_each_possible_cpu(cpu) { |
| memset(&cpu_rq(cpu)->uclamp, 0, |
| sizeof(struct uclamp_rq)*UCLAMP_CNT); |
| cpu_rq(cpu)->uclamp_flags = 0; |
| } |
| |
| for_each_clamp_id(clamp_id) { |
| uclamp_se_set(&init_task.uclamp_req[clamp_id], |
| uclamp_none(clamp_id), false); |
| } |
| |
| /* System defaults allow max clamp values for both indexes */ |
| uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false); |
| for_each_clamp_id(clamp_id) { |
| uclamp_default[clamp_id] = uc_max; |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| root_task_group.uclamp_req[clamp_id] = uc_max; |
| root_task_group.uclamp[clamp_id] = uc_max; |
| #endif |
| } |
| } |
| |
| #else /* CONFIG_UCLAMP_TASK */ |
| static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { } |
| static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { } |
| static inline int uclamp_validate(struct task_struct *p, |
| const struct sched_attr *attr) |
| { |
| return -EOPNOTSUPP; |
| } |
| static void __setscheduler_uclamp(struct task_struct *p, |
| const struct sched_attr *attr) { } |
| static inline void uclamp_fork(struct task_struct *p) { } |
| static inline void init_uclamp(void) { } |
| #endif /* CONFIG_UCLAMP_TASK */ |
| |
| static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) |
| { |
| if (!(flags & ENQUEUE_NOCLOCK)) |
| update_rq_clock(rq); |
| |
| if (!(flags & ENQUEUE_RESTORE)) { |
| sched_info_queued(rq, p); |
| psi_enqueue(p, flags & ENQUEUE_WAKEUP); |
| } |
| |
| uclamp_rq_inc(rq, p); |
| p->sched_class->enqueue_task(rq, p, flags); |
| } |
| |
| static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) |
| { |
| if (!(flags & DEQUEUE_NOCLOCK)) |
| update_rq_clock(rq); |
| |
| if (!(flags & DEQUEUE_SAVE)) { |
| sched_info_dequeued(rq, p); |
| psi_dequeue(p, flags & DEQUEUE_SLEEP); |
| } |
| |
| uclamp_rq_dec(rq, p); |
| p->sched_class->dequeue_task(rq, p, flags); |
| } |
| |
| void activate_task(struct rq *rq, struct task_struct *p, int flags) |
| { |
| if (task_contributes_to_load(p)) |
| rq->nr_uninterruptible--; |
| |
| enqueue_task(rq, p, flags); |
| |
| p->on_rq = TASK_ON_RQ_QUEUED; |
| } |
| |
| void deactivate_task(struct rq *rq, struct task_struct *p, int flags) |
| { |
| p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING; |
| |
| if (task_contributes_to_load(p)) |
| rq->nr_uninterruptible++; |
| |
| dequeue_task(rq, p, flags); |
| } |
| |
| /* |
| * __normal_prio - return the priority that is based on the static prio |
| */ |
| static inline int __normal_prio(struct task_struct *p) |
| { |
| return p->static_prio; |
| } |
| |
| /* |
| * Calculate the expected normal priority: i.e. priority |
| * without taking RT-inheritance into account. Might be |
| * boosted by interactivity modifiers. Changes upon fork, |
| * setprio syscalls, and whenever the interactivity |
| * estimator recalculates. |
| */ |
| static inline int normal_prio(struct task_struct *p) |
| { |
| int prio; |
| |
| if (task_has_dl_policy(p)) |
| prio = MAX_DL_PRIO-1; |
| else if (task_has_rt_policy(p)) |
| prio = MAX_RT_PRIO-1 - p->rt_priority; |
| else |
| prio = __normal_prio(p); |
| return prio; |
| } |
| |
| /* |
| * Calculate the current priority, i.e. the priority |
| * taken into account by the scheduler. This value might |
| * be boosted by RT tasks, or might be boosted by |
| * interactivity modifiers. Will be RT if the task got |
| * RT-boosted. If not then it returns p->normal_prio. |
| */ |
| static int effective_prio(struct task_struct *p) |
| { |
| p->normal_prio = normal_prio(p); |
| /* |
| * If we are RT tasks or we were boosted to RT priority, |
| * keep the priority unchanged. Otherwise, update priority |
| * to the normal priority: |
| */ |
| if (!rt_prio(p->prio)) |
| return p->normal_prio; |
| return p->prio; |
| } |
| |
| /** |
| * 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; |
| } |
| |
| /* |
| * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, |
| * use the balance_callback list if you want balancing. |
| * |
| * this means any call to check_class_changed() must be followed by a call to |
| * balance_callback(). |
| */ |
| static inline void check_class_changed(struct rq *rq, struct task_struct *p, |
| const struct sched_class *prev_class, |
| int oldprio) |
| { |
| if (prev_class != p->sched_class) { |
| if (prev_class->switched_from) |
| prev_class->switched_from(rq, p); |
| |
| p->sched_class->switched_to(rq, p); |
| } else if (oldprio != p->prio || dl_task(p)) |
| p->sched_class->prio_changed(rq, p, oldprio); |
| } |
| |
| void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) |
| { |
| const struct sched_class *class; |
| |
| if (p->sched_class == rq->curr->sched_class) { |
| rq->curr->sched_class->check_preempt_curr(rq, p, flags); |
| } else { |
| for_each_class(class) { |
| if (class == rq->curr->sched_class) |
| break; |
| if (class == p->sched_class) { |
| resched_curr(rq); |
| break; |
| } |
| } |
| } |
| |
| /* |
| * A queue event has occurred, and we're going to schedule. In |
| * this case, we can save a useless back to back clock update. |
| */ |
| if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) |
| rq_clock_skip_update(rq); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| static inline bool is_per_cpu_kthread(struct task_struct *p) |
| { |
| if (!(p->flags & PF_KTHREAD)) |
| return false; |
| |
| if (p->nr_cpus_allowed != 1) |
| return false; |
| |
| return true; |
| } |
| |
| /* |
| * 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) |
| { |
| if (!cpumask_test_cpu(cpu, p->cpus_ptr)) |
| return false; |
| |
| if (is_per_cpu_kthread(p)) |
| return cpu_online(cpu); |
| |
| return cpu_active(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. |
| */ |
| static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, |
| struct task_struct *p, int new_cpu) |
| { |
| lockdep_assert_held(&rq->lock); |
| |
| WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING); |
| dequeue_task(rq, p, DEQUEUE_NOCLOCK); |
| set_task_cpu(p, new_cpu); |
| rq_unlock(rq, rf); |
| |
| rq = cpu_rq(new_cpu); |
| |
| rq_lock(rq, rf); |
| BUG_ON(task_cpu(p) != new_cpu); |
| enqueue_task(rq, p, 0); |
| p->on_rq = TASK_ON_RQ_QUEUED; |
| check_preempt_curr(rq, p, 0); |
| |
| 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 rq_flags *rf, |
| struct task_struct *p, int dest_cpu) |
| { |
| /* Affinity changed (again). */ |
| if (!is_cpu_allowed(p, dest_cpu)) |
| return rq; |
| |
| update_rq_clock(rq); |
| rq = move_queued_task(rq, rf, p, dest_cpu); |
| |
| return rq; |
| } |
| |
| /* |
| * migration_cpu_stop - this will be executed by a highprio 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(); |
| struct rq_flags rf; |
| |
| /* |
| * The original target CPU might have gone down and we might |
| * be on another CPU but it doesn't matter. |
| */ |
| local_irq_disable(); |
| /* |
| * 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. |
| */ |
| sched_ttwu_pending(); |
| |
| raw_spin_lock(&p->pi_lock); |
| rq_lock(rq, &rf); |
| /* |
| * 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) { |
| if (task_on_rq_queued(p)) |
| rq = __migrate_task(rq, &rf, p, arg->dest_cpu); |
| else |
| p->wake_cpu = arg->dest_cpu; |
| } |
| rq_unlock(rq, &rf); |
| raw_spin_unlock(&p->pi_lock); |
| |
| local_irq_enable(); |
| return 0; |
| } |
| |
| /* |
| * sched_class::set_cpus_allowed must do the below, but is not required to |
| * actually call this function. |
| */ |
| void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) |
| { |
| cpumask_copy(&p->cpus_mask, new_mask); |
| p->nr_cpus_allowed = cpumask_weight(new_mask); |
| } |
| |
| void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) |
| { |
| struct rq *rq = task_rq(p); |
| bool queued, running; |
| |
| lockdep_assert_held(&p->pi_lock); |
| |
| queued = task_on_rq_queued(p); |
| running = task_current(rq, p); |
| |
| if (queued) { |
| /* |
| * Because __kthread_bind() calls this on blocked tasks without |
| * holding rq->lock. |
| */ |
| lockdep_assert_held(&rq->lock); |
| dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
| } |
| if (running) |
| put_prev_task(rq, p); |
| |
| p->sched_class->set_cpus_allowed(p, new_mask); |
| |
| if (queued) |
| enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| if (running) |
| set_next_task(rq, p); |
| } |
| |
| /* |
| * Change a given task's CPU affinity. Migrate the thread to a |
| * proper CPU and schedule it away if the CPU it's executing on |
| * 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. |
| */ |
| static int __set_cpus_allowed_ptr(struct task_struct *p, |
| const struct cpumask *new_mask, bool check) |
| { |
| const struct cpumask *cpu_valid_mask = cpu_active_mask; |
| unsigned int dest_cpu; |
| struct rq_flags rf; |
| struct rq *rq; |
| int ret = 0; |
| |
| rq = task_rq_lock(p, &rf); |
| update_rq_clock(rq); |
| |
| if (p->flags & PF_KTHREAD) { |
| /* |
| * Kernel threads are allowed on online && !active CPUs |
| */ |
| cpu_valid_mask = cpu_online_mask; |
| } |
| |
| /* |
| * Must re-check here, to close a race against __kthread_bind(), |
| * sched_setaffinity() is not guaranteed to observe the flag. |
| */ |
| if (check && (p->flags & PF_NO_SETAFFINITY)) { |
| ret = -EINVAL; |
| goto out; |
| } |
| |
| if (cpumask_equal(p->cpus_ptr, new_mask)) |
| goto out; |
| |
| dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); |
| if (dest_cpu >= nr_cpu_ids) { |
| ret = -EINVAL; |
| goto out; |
| } |
| |
| do_set_cpus_allowed(p, new_mask); |
| |
| if (p->flags & PF_KTHREAD) { |
| /* |
| * For kernel threads that do indeed end up on online && |
| * !active we want to ensure they are strict per-CPU threads. |
| */ |
| WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && |
| !cpumask_intersects(new_mask, cpu_active_mask) && |
| p->nr_cpus_allowed != 1); |
| } |
| |
| /* Can the task run on the task's current CPU? If so, we're done */ |
| if (cpumask_test_cpu(task_cpu(p), new_mask)) |
| goto out; |
| |
| if (task_running(rq, p) || p->state == TASK_WAKING) { |
| struct migration_arg arg = { p, dest_cpu }; |
| /* Need help from migration thread: drop lock and wait. */ |
| task_rq_unlock(rq, p, &rf); |
| stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); |
| return 0; |
| } else if (task_on_rq_queued(p)) { |
| /* |
| * OK, since we're going to drop the lock immediately |
| * afterwards anyway. |
| */ |
| rq = move_queued_task(rq, &rf, p, dest_cpu); |
| } |
| out: |
| task_rq_unlock(rq, p, &rf); |
| |
| return ret; |
| } |
| |
| int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) |
| { |
| return __set_cpus_allowed_ptr(p, new_mask, false); |
| } |
| EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); |
| |
| void set_task_cpu(struct task_struct *p, unsigned int new_cpu) |
| { |
| #ifdef CONFIG_SCHED_DEBUG |
| /* |
| * We should never call set_task_cpu() on a blocked task, |
| * ttwu() will sort out the placement. |
| */ |
| WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && |
| !p->on_rq); |
| |
| /* |
| * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, |
| * because schedstat_wait_{start,end} rebase migrating task's wait_start |
| * time relying on p->on_rq. |
| */ |
| WARN_ON_ONCE(p->state == TASK_RUNNING && |
| p->sched_class == &fair_sched_class && |
| (p->on_rq && !task_on_rq_migrating(p))); |
| |
| #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(). |
| * |
| * Furthermore, all task_rq users should acquire both locks, see |
| * task_rq_lock(). |
| */ |
| 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)); |
| #endif |
| |
| trace_sched_migrate_task(p, new_cpu); |
| |
| if (task_cpu(p) != new_cpu) { |
| if (p->sched_class->migrate_task_rq) |
| p->sched_class->migrate_task_rq(p, new_cpu); |
| p->se.nr_migrations++; |
| rseq_migrate(p); |
| perf_event_task_migrate(p); |
| } |
| |
| __set_task_cpu(p, new_cpu); |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| static void __migrate_swap_task(struct task_struct *p, int cpu) |
| { |
| if (task_on_rq_queued(p)) { |
| struct rq *src_rq, *dst_rq; |
| struct rq_flags srf, drf; |
| |
| src_rq = task_rq(p); |
| dst_rq = cpu_rq(cpu); |
| |
| rq_pin_lock(src_rq, &srf); |
| rq_pin_lock(dst_rq, &drf); |
| |
| deactivate_task(src_rq, p, 0); |
| set_task_cpu(p, cpu); |
| activate_task(dst_rq, p, 0); |
| check_preempt_curr(dst_rq, p, 0); |
| |
| rq_unpin_lock(dst_rq, &drf); |
| rq_unpin_lock(src_rq, &srf); |
| |
| } else { |
| /* |
| * Task isn't running anymore; make it appear like we migrated |
| * it before it went to sleep. This means on wakeup we make the |
| * previous CPU our target instead of where it really is. |
| */ |
| p->wake_cpu = cpu; |
| } |
| } |
| |
| struct migration_swap_arg { |
| struct task_struct *src_task, *dst_task; |
| int src_cpu, dst_cpu; |
| }; |
| |
| static int migrate_swap_stop(void *data) |
| { |
| struct migration_swap_arg *arg = data; |
| struct rq *src_rq, *dst_rq; |
| int ret = -EAGAIN; |
| |
| if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) |
| return -EAGAIN; |
| |
| src_rq = cpu_rq(arg->src_cpu); |
| dst_rq = cpu_rq(arg->dst_cpu); |
| |
| double_raw_lock(&arg->src_task->pi_lock, |
| &arg->dst_task->pi_lock); |
| double_rq_lock(src_rq, dst_rq); |
| |
| if (task_cpu(arg->dst_task) != arg->dst_cpu) |
| goto unlock; |
| |
| if (task_cpu(arg->src_task) != arg->src_cpu) |
| goto unlock; |
| |
| if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr)) |
| goto unlock; |
| |
| if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr)) |
| goto unlock; |
| |
| __migrate_swap_task(arg->src_task, arg->dst_cpu); |
| __migrate_swap_task(arg->dst_task, arg->src_cpu); |
| |
| ret = 0; |
| |
| unlock: |
| double_rq_unlock(src_rq, dst_rq); |
| raw_spin_unlock(&arg->dst_task->pi_lock); |
| raw_spin_unlock(&arg->src_task->pi_lock); |
| |
| return ret; |
| } |
| |
| /* |
| * Cross migrate two tasks |
| */ |
| int migrate_swap(struct task_struct *cur, struct task_struct *p, |
| int target_cpu, int curr_cpu) |
| { |
| struct migration_swap_arg arg; |
| int ret = -EINVAL; |
| |
| arg = (struct migration_swap_arg){ |
| .src_task = cur, |
| .src_cpu = curr_cpu, |
| .dst_task = p, |
| .dst_cpu = target_cpu, |
| }; |
| |
| if (arg.src_cpu == arg.dst_cpu) |
| goto out; |
| |
| /* |
| * These three tests are all lockless; this is OK since all of them |
| * will be re-checked with proper locks held further down the line. |
| */ |
| if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) |
| goto out; |
| |
| if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr)) |
| goto out; |
| |
| if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr)) |
| goto out; |
| |
| trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); |
| ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); |
| |
| out: |
| return ret; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| /* |
| * wait_task_inactive - wait for a thread to unschedule. |
| * |
| * If @match_state is nonzero, it's the @p->state value just checked and |
| * not expected to change. 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, long match_state) |
| { |
| int running, queued; |
| struct rq_flags rf; |
| unsigned long ncsw; |
| struct rq *rq; |
| |
| for (;;) { |
| /* |
| * We do the initial early heuristics without holding |
| * any task-queue locks at all. We'll only try to get |
| * the runqueue lock when things look like they will |
| * work out! |
| */ |
| 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 "task_running()" will |
| * return false if the runqueue has changed and p |
| * is actually now running somewhere else! |
| */ |
| while (task_running(rq, p)) { |
| if (match_state && unlikely(p->state != 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. |
| */ |
| rq = task_rq_lock(p, &rf); |
| trace_sched_wait_task(p); |
| running = task_running(rq, p); |
| queued = task_on_rq_queued(p); |
| ncsw = 0; |
| if (!match_state || p->state == match_state) |
| ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ |
| task_rq_unlock(rq, p, &rf); |
| |
| /* |
| * 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); |
| 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; |
| } |
| |
| /*** |
| * 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) |
| { |
| int cpu; |
| |
| preempt_disable(); |
| cpu = task_cpu(p); |
| if ((cpu != smp_processor_id()) && task_curr(p)) |
| smp_send_reschedule(cpu); |
| preempt_enable(); |
| } |
| 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 (!cpu_active(dest_cpu)) |
| continue; |
| if (cpumask_test_cpu(dest_cpu, p->cpus_ptr)) |
| 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 (IS_ENABLED(CONFIG_CPUSETS)) { |
| cpuset_cpus_allowed_fallback(p); |
| state = possible; |
| break; |
| } |
| /* Fall-through */ |
| case possible: |
| do_set_cpus_allowed(p, cpu_possible_mask); |
| 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; |
| } |
| |
| /* |
| * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable. |
| */ |
| static inline |
| int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) |
| { |
| lockdep_assert_held(&p->pi_lock); |
| |
| if (p->nr_cpus_allowed > 1) |
| cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); |
| else |
| cpu = cpumask_any(p->cpus_ptr); |
| |
| /* |
| * In order not to call set_task_cpu() on a blocking task we need |
| * to rely on ttwu() to place the task on a valid ->cpus_ptr |
| * CPU. |
| * |
| * Since this is common to all placement strategies, this lives here. |
| * |
| * [ this allows ->select_task() to simply return task_cpu(p) and |
| * not worry about this generic constraint ] |
| */ |
| if (unlikely(!is_cpu_allowed(p, cpu))) |
| cpu = select_fallback_rq(task_cpu(p), p); |
| |
| return cpu; |
| } |
| |
| static void update_avg(u64 *avg, u64 sample) |
| { |
| s64 diff = sample - *avg; |
| *avg += diff >> 3; |
| } |
| |
| void sched_set_stop_task(int cpu, struct task_struct *stop) |
| { |
| struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; |
| 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, ¶m); |
| |
| stop->sched_class = &stop_sched_class; |
| } |
| |
| cpu_rq(cpu)->stop = stop; |
| |
| if (old_stop) { |
| /* |
| * Reset it back to a normal scheduling class so that |
| * it can die in pieces. |
| */ |
| old_stop->sched_class = &rt_sched_class; |
| } |
| } |
| |
| #else |
| |
| static inline int __set_cpus_allowed_ptr(struct task_struct *p, |
| const struct cpumask *new_mask, bool check) |
| { |
| return set_cpus_allowed_ptr(p, new_mask); |
| } |
| |
| #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->se.statistics.nr_wakeups_local); |
| } else { |
| struct sched_domain *sd; |
| |
| __schedstat_inc(p->se.statistics.nr_wakeups_remote); |
| rcu_read_lock(); |
| for_each_domain(rq->cpu, sd) { |
| if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { |
| __schedstat_inc(sd->ttwu_wake_remote); |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| } |
| |
| if (wake_flags & WF_MIGRATED) |
| __schedstat_inc(p->se.statistics.nr_wakeups_migrate); |
| #endif /* CONFIG_SMP */ |
| |
| __schedstat_inc(rq->ttwu_count); |
| __schedstat_inc(p->se.statistics.nr_wakeups); |
| |
| if (wake_flags & WF_SYNC) |
| __schedstat_inc(p->se.statistics.nr_wakeups_sync); |
| } |
| |
| /* |
| * Mark the task runnable and perform wakeup-preemption. |
| */ |
| static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, |
| struct rq_flags *rf) |
| { |
| check_preempt_curr(rq, p, wake_flags); |
| p->state = TASK_RUNNING; |
| trace_sched_wakeup(p); |
| |
| #ifdef CONFIG_SMP |
| if (p->sched_class->task_woken) { |
| /* |
| * Our task @p is fully woken up and running; so its safe to |
| * drop the rq->lock, hereafter rq is only used for statistics. |
| */ |
| rq_unpin_lock(rq, rf); |
| p->sched_class->task_woken(rq, p); |
| rq_repin_lock(rq, rf); |
| } |
| |
| if (rq->idle_stamp) { |
| u64 delta = rq_clock(rq) - rq->idle_stamp; |
| u64 max = 2*rq->max_idle_balance_cost; |
| |
| update_avg(&rq->avg_idle, delta); |
| |
| if (rq->avg_idle > max) |
| rq->avg_idle = max; |
| |
| rq->idle_stamp = 0; |
| } |
| #endif |
| } |
| |
| static void |
| ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, |
| struct rq_flags *rf) |
| { |
| int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK; |
| |
| lockdep_assert_held(&rq->lock); |
| |
| #ifdef CONFIG_SMP |
| if (p->sched_contributes_to_load) |
| rq->nr_uninterruptible--; |
| |
| if (wake_flags & WF_MIGRATED) |
| en_flags |= ENQUEUE_MIGRATED; |
| #endif |
| |
| activate_task(rq, p, en_flags); |
| ttwu_do_wakeup(rq, p, wake_flags, rf); |
| } |
| |
| /* |
| * Called in case the task @p isn't fully descheduled from its runqueue, |
| * in this case we must do a remote wakeup. Its a 'light' wakeup though, |
| * since all we need to do is flip p->state to TASK_RUNNING, since |
| * the task is still ->on_rq. |
| */ |
| static int ttwu_remote(struct task_struct *p, int wake_flags) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| int ret = 0; |
| |
| rq = __task_rq_lock(p, &rf); |
| if (task_on_rq_queued(p)) { |
| /* check_preempt_curr() may use rq clock */ |
| update_rq_clock(rq); |
| ttwu_do_wakeup(rq, p, wake_flags, &rf); |
| ret = 1; |
| } |
| __task_rq_unlock(rq, &rf); |
| |
| return ret; |
| } |
| |
| #ifdef CONFIG_SMP |
| void sched_ttwu_pending(void) |
| { |
| struct rq *rq = this_rq(); |
| struct llist_node *llist = llist_del_all(&rq->wake_list); |
| 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) |
| ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); |
| |
| rq_unlock_irqrestore(rq, &rf); |
| } |
| |
| void scheduler_ipi(void) |
| { |
| /* |
| * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting |
| * TIF_NEED_RESCHED remotely (for the first time) will also send |
| * this IPI. |
| */ |
| preempt_fold_need_resched(); |
| |
| if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) |
| return; |
| |
| /* |
| * Not all reschedule IPI handlers call irq_enter/irq_exit, since |
| * traditionally all their work was done from the interrupt return |
| * path. Now that we actually do some work, we need to make sure |
| * we do call them. |
| * |
| * Some archs already do call them, luckily irq_enter/exit nest |
| * properly. |
| * |
| * Arguably we should visit all archs and update all handlers, |
| * however a fair share of IPIs are still resched only so this would |
| * somewhat pessimize the simple resched case. |
| */ |
| irq_enter(); |
| sched_ttwu_pending(); |
| |
| /* |
| * Check if someone kicked us for doing the nohz idle load balance. |
| */ |
| if (unlikely(got_nohz_idle_kick())) { |
| this_rq()->idle_balance = 1; |
| raise_softirq_irqoff(SCHED_SOFTIRQ); |
| } |
| irq_exit(); |
| } |
| |
| static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); |
| |
| if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { |
| if (!set_nr_if_polling(rq->idle)) |
| smp_send_reschedule(cpu); |
| else |
| trace_sched_wake_idle_without_ipi(cpu); |
| } |
| } |
| |
| void wake_up_if_idle(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct rq_flags rf; |
| |
| rcu_read_lock(); |
| |
| if (!is_idle_task(rcu_dereference(rq->curr))) |
| goto out; |
| |
| if (set_nr_if_polling(rq->idle)) { |
| trace_sched_wake_idle_without_ipi(cpu); |
| } else { |
| rq_lock_irqsave(rq, &rf); |
| if (is_idle_task(rq->curr)) |
| smp_send_reschedule(cpu); |
| /* Else CPU is not idle, do nothing here: */ |
| rq_unlock_irqrestore(rq, &rf); |
| } |
| |
| out: |
| rcu_read_unlock(); |
| } |
| |
| bool cpus_share_cache(int this_cpu, int that_cpu) |
| { |
| return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); |
| } |
| #endif /* CONFIG_SMP */ |
| |
| static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct rq_flags rf; |
| |
| #if defined(CONFIG_SMP) |
| if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { |
| sched_clock_cpu(cpu); /* Sync clocks across CPUs */ |
| ttwu_queue_remote(p, cpu, wake_flags); |
| return; |
| } |
| #endif |
| |
| rq_lock(rq, &rf); |
| update_rq_clock(rq); |
| ttwu_do_activate(rq, p, wake_flags, &rf); |
| rq_unlock(rq, &rf); |
| } |
| |
| /* |
| * 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 |
| * |
| * Release/acquire chaining guarantees that B happens after A and C after B. |
| * 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) |
| * 2) smp_cond_load_acquire(!X->on_cpu) |
| * |
| * 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 ensure that CONDITION=1 done by the caller can not be reordered with |
| * accesses to the task state; see try_to_wake_up() and set_current_state(). |
| */ |
| |
| /** |
| * 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_*) |
| * |
| * If (@state & @p->state) @p->state = TASK_RUNNING. |
| * |
| * If the task was not queued/runnable, also place it back on a runqueue. |
| * |
| * Atomic against schedule() which would dequeue a task, also see |
| * set_current_state(). |
| * |
| * This function executes a full memory barrier before accessing the task |
| * state; see set_current_state(). |
| * |
| * Return: %true if @p->state changes (an actual wakeup was done), |
| * %false otherwise. |
| */ |
| static int |
| try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) |
| { |
| unsigned long flags; |
| int cpu, success = 0; |
| |
| preempt_disable(); |
| 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_remote()' 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 (!(p->state & state)) |
| goto out; |
| |
| success = 1; |
| cpu = task_cpu(p); |
| trace_sched_waking(p); |
| p->state = TASK_RUNNING; |
| trace_sched_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 mb() in |
| * set_current_state() the waiting thread does. |
| */ |
| raw_spin_lock_irqsave(&p->pi_lock, flags); |
| smp_mb__after_spinlock(); |
| if (!(p->state & state)) |
| goto unlock; |
| |
| trace_sched_waking(p); |
| |
| /* We're going to change ->state: */ |
| success = 1; |
| cpu = task_cpu(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(). |
| */ |
| smp_rmb(); |
| if (p->on_rq && ttwu_remote(p, wake_flags)) |
| goto unlock; |
| |
| #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(). |
| */ |
| smp_rmb(); |
| |
| /* |
| * If the owning (remote) CPU is still in the middle of schedule() with |
| * this task as prev, wait until its 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); |
| |
| p->sched_contributes_to_load = !!task_contributes_to_load(p); |
| p->state = TASK_WAKING; |
| |
| if (p->in_iowait) { |
| delayacct_blkio_end(p); |
| atomic_dec(&task_rq(p)->nr_iowait); |
| } |
| |
| cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); |
| if (task_cpu(p) != cpu) { |
| wake_flags |= WF_MIGRATED; |
| psi_ttwu_dequeue(p); |
| set_task_cpu(p, cpu); |
| } |
| |
| #else /* CONFIG_SMP */ |
| |
| if (p->in_iowait) { |
| delayacct_blkio_end(p); |
| atomic_dec(&task_rq(p)->nr_iowait); |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| ttwu_queue(p, cpu, wake_flags); |
| unlock: |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| out: |
| if (success) |
| ttwu_stat(p, cpu, wake_flags); |
| preempt_enable(); |
| |
| return success; |
| } |
| |
| /** |
| * 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 used by init_idle() too: |
| */ |
| static void __sched_fork(unsigned long clone_flags, struct task_struct *p) |
| { |
| p->on_rq = 0; |
| |
| p->se.on_rq = 0; |
| p->se.exec_start = 0; |
| p->se.sum_exec_runtime = 0; |
| p->se.prev_sum_exec_runtime = 0; |
| p->se.nr_migrations = 0; |
| p->se.vruntime = 0; |
| INIT_LIST_HEAD(&p->se.group_node); |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| p->se.cfs_rq = NULL; |
| #endif |
| |
| #ifdef CONFIG_SCHEDSTATS |
| /* Even if schedstat is disabled, there should not be garbage */ |
| memset(&p->se.statistics, 0, sizeof(p->se.statistics)); |
| #endif |
| |
| RB_CLEAR_NODE(&p->dl.rb_node); |
| init_dl_task_timer(&p->dl); |
| init_dl_inactive_task_timer(&p->dl); |
| __dl_clear_params(p); |
| |
| INIT_LIST_HEAD(&p->rt.run_list); |
| p->rt.timeout = 0; |
| p->rt.time_slice = sched_rr_timeslice; |
| p->rt.on_rq = 0; |
| p->rt.on_list = 0; |
| |
| #ifdef CONFIG_PREEMPT_NOTIFIERS |
| INIT_HLIST_HEAD(&p->preempt_notifiers); |
| #endif |
| |
| #ifdef CONFIG_COMPACTION |
| p->capture_control = NULL; |
| #endif |
| init_numa_balancing(clone_flags, p); |
| } |
| |
| DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| |
| void set_numabalancing_state(bool enabled) |
| { |
| if (enabled) |
| static_branch_enable(&sched_numa_balancing); |
| else |
| static_branch_disable(&sched_numa_balancing); |
| } |
| |
| #ifdef CONFIG_PROC_SYSCTL |
| int sysctl_numa_balancing(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| struct ctl_table t; |
| int err; |
| int state = static_branch_likely(&sched_numa_balancing); |
| |
| 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_numabalancing_state(state); |
| return err; |
| } |
| #endif |
| #endif |
| |
| #ifdef CONFIG_SCHEDSTATS |
| |
| DEFINE_STATIC_KEY_FALSE(sched_schedstats); |
| static bool __initdata __sched_schedstats = false; |
| |
| 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; |
| |
| /* |
| * This code is called before jump labels have been set up, so we can't |
| * change the static branch directly just yet. Instead set a temporary |
| * variable so init_schedstats() can do it later. |
| */ |
| if (!strcmp(str, "enable")) { |
| __sched_schedstats = true; |
| ret = 1; |
| } else if (!strcmp(str, "disable")) { |
| __sched_schedstats = false; |
| ret = 1; |
| } |
| out: |
| if (!ret) |
| pr_warn("Unable to parse schedstats=\n"); |
| |
| return ret; |
| } |
| __setup("schedstats=", setup_schedstats); |
| |
| static void __init init_schedstats(void) |
| { |
| set_schedstats(__sched_schedstats); |
| } |
| |
| #ifdef CONFIG_PROC_SYSCTL |
| int sysctl_schedstats(struct ctl_table *table, int write, |
| void __user *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; |
| } |
| #endif /* CONFIG_PROC_SYSCTL */ |
| #else /* !CONFIG_SCHEDSTATS */ |
| static inline void init_schedstats(void) {} |
| #endif /* CONFIG_SCHEDSTATS */ |
| |
| /* |
| * fork()/clone()-time setup: |
| */ |
| int sched_fork(unsigned long clone_flags, struct task_struct *p) |
| { |
| unsigned long flags; |
| |
| __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; |
| |
| uclamp_fork(p); |
| |
| /* |
| * Revert to default priority/policy on fork if requested. |
| */ |
| if (unlikely(p->sched_reset_on_fork)) { |
| if (task_has_dl_policy(p) || 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 = __normal_prio(p); |
| set_load_weight(p, false); |
| |
| /* |
| * We don't need the reset flag anymore after the fork. It has |
| * fulfilled its duty: |
| */ |
| p->sched_reset_on_fork = 0; |
| } |
| |
| if (dl_prio(p->prio)) |
| return -EAGAIN; |
| else if (rt_prio(p->prio)) |
| p->sched_class = &rt_sched_class; |
| else |
| p->sched_class = &fair_sched_class; |
| |
| init_entity_runnable_average(&p->se); |
| |
| /* |
| * The child is not yet in the pid-hash so no cgroup attach races, |
| * and the cgroup is pinned to this child due to cgroup_fork() |
| * is ran before sched_fork(). |
| * |
| * Silence PROVE_RCU. |
| */ |
| raw_spin_lock_irqsave(&p->pi_lock, flags); |
| /* |
| * 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()); |
| if (p->sched_class->task_fork) |
| p->sched_class->task_fork(p); |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| |
| #ifdef CONFIG_SCHED_INFO |
| if (likely(sched_info_on())) |
| memset(&p->sched_info, 0, sizeof(p->sched_info)); |
| #endif |
| #if defined(CONFIG_SMP) |
| p->on_cpu = 0; |
| #endif |
| init_task_preempt_count(p); |
| #ifdef CONFIG_SMP |
| plist_node_init(&p->pushable_tasks, MAX_PRIO); |
| RB_CLEAR_NODE(&p->pushable_dl_tasks); |
| #endif |
| return 0; |
| } |
| |
| unsigned long to_ratio(u64 period, u64 runtime) |
| { |
| if (runtime == RUNTIME_INF) |
| return BW_UNIT; |
| |
| /* |
| * Doing this here saves a lot of checks in all |
| * the calling paths, and returning zero seems |
| * safe for them anyway. |
| */ |
| if (period == 0) |
| return 0; |
| |
| return div64_u64(runtime << BW_SHIFT, period); |
| } |
| |
| /* |
| * 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) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| raw_spin_lock_irqsave(&p->pi_lock, rf.flags); |
| p->state = TASK_RUNNING; |
| #ifdef CONFIG_SMP |
| /* |
| * 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. |
| */ |
| p->recent_used_cpu = task_cpu(p); |
| __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); |
| #endif |
| rq = __task_rq_lock(p, &rf); |
| update_rq_clock(rq); |
| post_init_entity_util_avg(p); |
| |
| activate_task(rq, p, ENQUEUE_NOCLOCK); |
| trace_sched_wakeup_new(p); |
| check_preempt_curr(rq, p, WF_FORK); |
| #ifdef CONFIG_SMP |
| if (p->sched_class->task_woken) { |
| /* |
| * Nothing relies on rq->lock after this, so its fine to |
| * drop it. |
| */ |
| rq_unpin_lock(rq, &rf); |
| p->sched_class->task_woken(rq, p); |
| rq_repin_lock(rq, &rf); |
| } |
| #endif |
| task_rq_unlock(rq, p, &rf); |
| } |
| |
| #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) |
| { |
| #ifdef CONFIG_SMP |
| /* |
| * Claim the task as running, we do this before switching to it |
| * such that any running task will have this set. |
| */ |
| next->on_cpu = 1; |
| #endif |
| } |
| |
| static inline void finish_task(struct task_struct *prev) |
| { |
| #ifdef CONFIG_SMP |
| /* |
| * After ->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); |
| #endif |
| } |
| |
| static inline void |
| prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf) |
| { |
| /* |
| * 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: |
| */ |
| rq_unpin_lock(rq, rf); |
| 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_); |
| 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 |
| |
| /** |
| * prepare_task_switch - prepare to switch tasks |
| * @rq: the runqueue preparing to switch |
| * @prev: the current task that is being switched out |
| * @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); |
| prepare_task(next); |
| prepare_arch_switch(next); |
| } |
| |
| /** |
| * finish_task_switch - clean up after a 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; |
| long 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 = prev->state; |
| vtime_task_switch(prev); |
| perf_event_task_sched_in(prev, current); |
| finish_task(prev); |
| finish_lock_switch(rq); |
| finish_arch_post_lock_switch(); |
| kcov_finish_switch(current); |
| |
| 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(mm); |
| } |
| if (unlikely(prev_state == TASK_DEAD)) { |
| if (prev->sched_class->task_dead) |
| prev->sched_class->task_dead(prev); |
| |
| /* |
| * Remove function-return probe instances associated with this |
| * task and put them back on the free list. |
| */ |
| kprobe_flush_task(prev); |
| |
| /* Task is done with its stack. */ |
| put_task_stack(prev); |
| |
| put_task_struct_rcu_user(prev); |
| } |
| |
| tick_nohz_task_switch(); |
| return rq; |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| /* rq->lock is NOT held, but preemption is disabled */ |
| static void __balance_callback(struct rq *rq) |
| { |
| struct callback_head *head, *next; |
| void (*func)(struct rq *rq); |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| head = rq->balance_callback; |
| rq->balance_callback = NULL; |
| while (head) { |
| func = (void (*)(struct rq *))head->func; |
| next = head->next; |
| head->next = NULL; |
| head = next; |
| |
| func(rq); |
| } |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| static inline void balance_callback(struct rq *rq) |
| { |
| if (unlikely(rq->balance_callback)) |
| __balance_callback(rq); |
| } |
| |
| #else |
| |
| static inline void balance_callback(struct rq *rq) |
| { |
| } |
| |
| #endif |
| |
| /** |
| * 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) |
| { |
| struct rq *rq; |
| |
| /* |
| * 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). |
| */ |
| |
| rq = finish_task_switch(prev); |
| balance_callback(rq); |
| 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, struct rq_flags *rf) |
| { |
| 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 |
| */ |
| 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); |
| |
| if (!prev->mm) { // from kernel |
| /* will mmdrop() in finish_task_switch(). */ |
| rq->prev_mm = prev->active_mm; |
| prev->active_mm = NULL; |
| } |
| } |
| |
| rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
| |
| prepare_lock_switch(rq, next, rf); |
| |
| /* Here we just switch the register state and the stack. */ |
| switch_to(prev, next, prev); |
| barrier(); |
| |
| return finish_task_switch(prev); |
| } |
| |
| /* |
| * nr_running and nr_context_switches: |
| * |
| * externally visible scheduler statistics: current number of runnable |
| * threads, total number of context switches performed since bootup. |
| */ |
| unsigned long nr_running(void) |
| { |
| unsigned long 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(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 long nr_iowait_cpu(int cpu) |
| { |
| return atomic_read(&cpu_rq(cpu)->nr_iowait); |
| } |
| |
| /* |
| * IO-wait accounting, and how its 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 long nr_iowait(void) |
| { |
| unsigned long 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) |
| { |
| struct task_struct *p = current; |
| unsigned long flags; |
| int dest_cpu; |
| |
| raw_spin_lock_irqsave(&p->pi_lock, flags); |
| dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); |
| if (dest_cpu == smp_processor_id()) |
| goto unlock; |
| |
| if (likely(cpu_active(dest_cpu))) { |
| struct migration_arg arg = { p, dest_cpu }; |
| |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); |
| return; |
| } |
| unlock: |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| } |
| |
| #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); |
| |
| /* |
| * The function fair_sched_class.update_curr accesses the struct curr |
| * and its field curr->exec_start; when called from task_sched_runtime(), |
| * we observe a high rate of cache misses in practice. |
| * Prefetching this data results in improved performance. |
| */ |
| static inline void prefetch_curr_exec_start(struct task_struct *p) |
| { |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| struct sched_entity *curr = (&p->se)->cfs_rq->curr; |
| #else |
| struct sched_entity *curr = (&task_rq(p)->cfs)->curr; |
| #endif |
| prefetch(curr); |
| prefetch(&curr->exec_start); |
| } |
| |
| /* |
| * Return accounted runtime for the task. |
| * In case the task is currently running, return the runtime plus current's |
| * pending runtime that have not been accounted yet. |
| */ |
| unsigned long long task_sched_runtime(struct task_struct *p) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| 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 p->se.sum_exec_runtime; |
| #endif |
| |
| rq = task_rq_lock(p, &rf); |
| /* |
| * Must be ->curr _and_ ->on_rq. If dequeued, we would |
| * project cycles that may never be accounted to this |
| * thread, breaking clock_gettime(). |
| */ |
| if (task_current(rq, p) && task_on_rq_queued(p)) { |
| prefetch_curr_exec_start(p); |
| update_rq_clock(rq); |
| p->sched_class->update_curr(rq); |
| } |
| ns = p->se.sum_exec_runtime; |
| task_rq_unlock(rq, p, &rf); |
| |
| return ns; |
| } |
| |
| /* |
| * This function gets called by the timer code, with HZ frequency. |
| * We call it with interrupts disabled. |
| */ |
| void scheduler_tick(void) |
| { |
| int cpu = smp_processor_id(); |
| struct rq *rq = cpu_rq(cpu); |
| struct task_struct *curr = rq->curr; |
| struct rq_flags rf; |
| |
| sched_clock_tick(); |
| |
| rq_lock(rq, &rf); |
| |
| update_rq_clock(rq); |
| curr->sched_class->task_tick(rq, curr, 0); |
| calc_global_load_tick(rq); |
| psi_task_tick(rq); |
| |
| rq_unlock(rq, &rf); |
| |
| perf_event_task_tick(); |
| |
| #ifdef CONFIG_SMP |
| rq->idle_balance = idle_cpu(cpu); |
| trigger_load_balance(rq); |
| #endif |
| } |
| |
| #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); |
| struct task_struct *curr; |
| struct rq_flags rf; |
| u64 delta; |
| 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 (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu)) |
| goto out_requeue; |
| |
| rq_lock_irq(rq, &rf); |
| curr = rq->curr; |
| if (is_idle_task(curr) || cpu_is_offline(cpu)) |
| goto out_unlock; |
| |
| update_rq_clock(rq); |
| delta = rq_clock_task(rq) - curr->se.exec_start; |
| |
| /* |
| * Make sure the next tick runs within a reasonable |
| * amount of time. |
| */ |
| WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); |
| curr->sched_class->task_tick(rq, curr, 0); |
| |
| out_unlock: |
| rq_unlock_irq(rq, &rf); |
| |
| out_requeue: |
| /* |
| * 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_FLAG_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_FLAG_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_TRACE_PREEMPT_TOGGLE)) |
| /* |
| * 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) |
| && in_atomic_preempt_off()) { |
| pr_err("Preemption disabled at:"); |
| print_ip_sym(preempt_disable_ip); |
| pr_cont("\n"); |
| } |
| if (panic_on_warn) |
| panic("scheduling while atomic\n"); |
| |
| 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"); |
| #endif |
| |
| #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
| if (!preempt && 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(); |
| |
| profile_hit(SCHED_PROFILING, __builtin_return_address(0)); |
| |
| schedstat_inc(this_rq()->sched_count); |
| } |
| |
| /* |
| * Pick up the highest-prio task: |
| */ |
| static inline struct task_struct * |
| pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
| { |
| const struct sched_class *class; |
| struct task_struct *p; |
| |
| /* |
| * Optimization: we know that if all tasks are in the fair class we can |
| * call that function directly, but only if the @prev task wasn't of a |
| * higher scheduling class, because otherwise those loose the |
| * opportunity to pull in more work from other CPUs. |
| */ |
| if (likely((prev->sched_class == &idle_sched_class || |
| prev->sched_class == &fair_sched_class) && |
| rq->nr_running == rq->cfs.h_nr_running)) { |
| |
| p = pick_next_task_fair(rq, prev, rf); |
| if (unlikely(p == RETRY_TASK)) |
| goto restart; |
| |
| /* Assumes fair_sched_class->next == idle_sched_class */ |
| if (!p) { |
| put_prev_task(rq, prev); |
| p = pick_next_task_idle(rq); |
| } |
| |
| return p; |
| } |
| |
| restart: |
| #ifdef CONFIG_SMP |
| /* |
| * We must do the balancing pass before put_next_task(), such |
| * that when we release the rq->lock the task is in the same |
| * state as before we took rq->lock. |
| * |
| * We can terminate the balance pass as soon as we know there is |
| * a runnable task of @class priority or higher. |
| */ |
| for_class_range(class, prev->sched_class, &idle_sched_class) { |
| if (class->balance(rq, prev, rf)) |
| break; |
| } |
| #endif |
| |
| put_prev_task(rq, prev); |
| |
| for_each_class(class) { |
| p = class->pick_next_task(rq); |
| if (p) |
| return p; |
| } |
| |
| /* The idle class should always have a runnable task: */ |
| BUG(); |
| } |
| |
| /* |
| * __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 scheduler_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(bool preempt) |
| { |
| struct task_struct *prev, *next; |
| unsigned long *switch_count; |
| struct rq_flags rf; |
| struct rq *rq; |
| int cpu; |
| |
| cpu = smp_processor_id(); |
| rq = cpu_rq(cpu); |
| prev = rq->curr; |
| |
| schedule_debug(prev, preempt); |
| |
| if (sched_feat(HRTICK)) |
| 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(). |
| * |
| * The membarrier system call requires a full memory barrier |
| * after coming from user-space, before storing to rq->curr. |
| */ |
| rq_lock(rq, &rf); |
| smp_mb__after_spinlock(); |
| |
| /* Promote REQ to ACT */ |
| rq->clock_update_flags <<= 1; |
| update_rq_clock(rq); |
| |
| switch_count = &prev->nivcsw; |
| if (!preempt && prev->state) { |
| if (signal_pending_state(prev->state, prev)) { |
| prev->state = TASK_RUNNING; |
| } else { |
| deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK); |
| |
| if (prev->in_iowait) { |
| atomic_inc(&rq->nr_iowait); |
| delayacct_blkio_start(); |
| } |
| } |
| switch_count = &prev->nvcsw; |
| } |
| |
| next = pick_next_task(rq, prev, &rf); |
| clear_tsk_need_resched(prev); |
| clear_preempt_need_resched(); |
| |
| if (likely(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. |
| * switch_mm() rely on membarrier_arch_switch_mm() on PowerPC. |
| * - 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), |
| */ |
| ++*switch_count; |
| |
| trace_sched_switch(preempt, prev, next); |
| |
| /* Also unlocks the rq: */ |
| rq = context_switch(rq, prev, next, &rf); |
| } else { |
| rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
| rq_unlock_irq(rq, &rf); |
| } |
| |
| balance_callback(rq); |
| } |
| |
| 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(false); |
| 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) |
| { |
| if (!tsk->state) |
| return; |
| |
| /* |
| * If a worker went to sleep, notify and ask workqueue whether |
| * it wants to wake up a task to maintain concurrency. |
| * As this function is called inside the schedule() context, |
| * we disable preemption to avoid it calling schedule() again |
| * in the possible wakeup of a kworker. |
| */ |
| if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) { |
| preempt_disable(); |
| if (tsk->flags & PF_WQ_WORKER) |
| wq_worker_sleeping(tsk); |
| else |
| io_wq_worker_sleeping(tsk); |
| preempt_enable_no_resched(); |
| } |
| |
| if (tsk_is_pi_blocked(tsk)) |
| return; |
| |
| /* |
| * If we are going to sleep and we have plugged IO queued, |
| * make sure to submit it to avoid deadlocks. |
| */ |
| if (blk_needs_flush_plug(tsk)) |
| blk_schedule_flush_plug(tsk); |
| } |
| |
| static void sched_update_worker(struct task_struct *tsk) |
| { |
| if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) { |
| if (tsk->flags & PF_WQ_WORKER) |
| wq_worker_running(tsk); |
| else |
| io_wq_worker_running(tsk); |
| } |
| } |
| |
| asmlinkage __visible void __sched schedule(void) |
| { |
| struct task_struct *tsk = current; |
| |
| sched_submit_work(tsk); |
| do { |
| preempt_disable(); |
| __schedule(false); |
| sched_preempt_enable_no_resched(); |
| } while (need_resched()); |
| 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(false); |
| } while (need_resched()); |
| } |
| |
| #ifdef CONFIG_CONTEXT_TRACKING |
| 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 != CONTEXT_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(); |
| } |
| |
| 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(true); |
| 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); |
| |
| /** |
| * 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(true); |
| exception_exit(prev_ctx); |
| |
| preempt_latency_stop(1); |
| preempt_enable_no_resched_notrace(); |
| } while (need_resched()); |
| } |
| EXPORT_SYMBOL_GPL(preempt_schedule_notrace); |
| |
| #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. |
| */ |
| 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(true); |
| 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) |
| { |
| return try_to_wake_up(curr->private, mode, wake_flags); |
| } |
| EXPORT_SYMBOL(default_wake_function); |
| |
| #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); |
| } |
| |
| /* |
| * 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, oldprio, queued, running, queue_flag = |
| DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| const struct sched_class *prev_class; |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| /* 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 && !dl_prio(prio)) |
| return; |
| |
| rq = __task_rq_lock(p, &rf); |
| update_rq_clock(rq); |
| /* |
| * 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 guaratees 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 && !dl_prio(prio)) |
| goto out_unlock; |
| |
| /* |
| * Idle task boosting is a nono 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); |
| oldprio = p->prio; |
| |
| if (oldprio == prio) |
| queue_flag &= ~DEQUEUE_MOVE; |
| |
| prev_class = p->sched_class; |
| queued = task_on_rq_queued(p); |
| running = task_current(rq, p); |
| if (queued) |
| dequeue_task(rq, p, queue_flag); |
| if (running) |
| put_prev_task(rq, p); |
| |
| /* |
| * Boosting condition are: |
| * 1. -rt task is running and holds mutex A |
| * --> -dl task blocks on mutex A |
| * |
| * 2. -dl task is running and holds mutex A |
| * --> -dl task blocks on mutex A and could preempt the |
| * running task |
| */ |
| if (dl_prio(prio)) { |
| if (!dl_prio(p->normal_prio) || |
| (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { |
| p->dl.dl_boosted = 1; |
| queue_flag |= ENQUEUE_REPLENISH; |
| } else |
| p->dl.dl_boosted = 0; |
| p->sched_class = &dl_sched_class; |
| } else if (rt_prio(prio)) { |
| if (dl_prio(oldprio)) |
| p->dl.dl_boosted = 0; |
| if (oldprio < prio) |
| queue_flag |= ENQUEUE_HEAD; |
| p->sched_class = &rt_sched_class; |
| } else { |
| if (dl_prio(oldprio)) |
| p->dl.dl_boosted = 0; |
| if (rt_prio(oldprio)) |
| p->rt.timeout = 0; |
| p->sched_class = &fair_sched_class; |
| } |
| |
| p->prio = prio; |
| |
| if (queued) |
| enqueue_task(rq, p, queue_flag); |
| if (running) |
| set_next_task(rq, p); |
| |
| check_class_changed(rq, p, prev_class, oldprio); |
| out_unlock: |
| /* Avoid rq from going away on us: */ |
| preempt_disable(); |
| __task_rq_unlock(rq, &rf); |
| |
| balance_callback(rq); |
| preempt_enable(); |
| } |
| #else |
| static inline int rt_effective_prio(struct task_struct *p, int prio) |
| { |
| return prio; |
| } |
| #endif |
| |
| void set_user_nice(struct task_struct *p, long nice) |
| { |
| bool queued, running; |
| int old_prio; |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| 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. |
| */ |
| rq = task_rq_lock(p, &rf); |
| update_rq_clock(rq); |
| |
| /* |
| * The RT priorities are set via sched_setscheduler(), but we still |
| * allow the 'normal' nice value to be set - but as expected |
| * it wont have any effect on scheduling until the task is |
| * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: |
| */ |
| if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
| p->static_prio = NICE_TO_PRIO(nice); |
| goto out_unlock; |
| } |
| queued = task_on_rq_queued(p); |
| running = task_current(rq, p); |
| if (queued) |
| dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
| if (running) |
| put_prev_task(rq, p); |
| |
| p->static_prio = NICE_TO_PRIO(nice); |
| set_load_weight(p, true); |
| old_prio = p->prio; |
| p->prio = effective_prio(p); |
| |
| if (queued) |
| enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| if (running) |
| set_next_task(rq, p); |
| |
| /* |
| * If the task increased its priority or is running and |
| * lowered its priority, then reschedule its CPU: |
| */ |
| p->sched_class->prio_changed(rq, p, old_prio); |
| |
| out_unlock: |
| task_rq_unlock(rq, p, &rf); |
| } |
| EXPORT_SYMBOL(set_user_nice); |
| |
| /* |
| * can_nice - check if a task can reduce its nice value |
| * @p: task |
| * @nice: nice value |
| */ |
| int can_nice(const struct task_struct *p, const int nice) |
| { |
| /* Convert nice value [19,-20] to rlimit style value [1,40]: */ |
| int nice_rlim = nice_to_rlimit(nice); |
| |
| return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || |
| capable(CAP_SYS_NICE)); |
| } |
| |
| #ifdef __ARCH_WANT_SYS_NICE |
| |
| /* |
| * sys_nice - change the priority of the current process. |
| * @increment: priority increment |
| * |
| * sys_setpriority is a more generic, but much slower function that |
| * does similar things. |
| */ |
| SYSCALL_DEFINE1(nice, int, increment) |
| { |
| long nice, retval; |
| |
| /* |
| * Setpriority might change our priority at the same moment. |
| * We don't have to worry. Conceptually one call occurs first |
| * and we have a single winner. |
| */ |
| increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); |
| nice = task_nice(current) + increment; |
| |
| nice = clamp_val(nice, MIN_NICE, MAX_NICE); |
| if (increment < 0 && !can_nice(current, nice)) |
| return -EPERM; |
| |
| retval = security_task_setnice(current, nice); |
| if (retval) |
| return retval; |
| |
| set_user_nice(current, nice); |
| return 0; |
| } |
| |
| #endif |
| |
| /** |
| * task_prio - return the priority value of a given task. |
| * @p: the task in question. |
| * |
| * Return: The priority value as seen by users in /proc. |
| * RT tasks are offset by -200. Normal tasks are centered |
| * around 0, value goes from -16 to +15. |
| */ |
| int task_prio(const struct task_struct *p) |
| { |
| return p->prio - MAX_RT_PRIO; |
| } |
| |
| /** |
| * idle_cpu - is a given CPU idle currently? |
| * @cpu: the processor in question. |
| * |
| * Return: 1 if the CPU is currently idle. 0 otherwise. |
| */ |
| int idle_cpu(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| if (rq->curr != rq->idle) |
| return 0; |
| |
| if (rq->nr_running) |
| return 0; |
| |
| #ifdef CONFIG_SMP |
| if (!llist_empty(&rq->wake_list)) |
| return 0; |
| #endif |
| |
| return 1; |
| } |
| |
| /** |
| * available_idle_cpu - is a given CPU idle for enqueuing work. |
| * @cpu: the CPU in question. |
| * |
| * Return: 1 if the CPU is currently idle. 0 otherwise. |
| */ |
| int available_idle_cpu(int cpu) |
| { |
| if (!idle_cpu(cpu)) |
| return 0; |
| |
| if (vcpu_is_preempted(cpu)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /** |
| * idle_task - return the idle task for a given CPU. |
| * @cpu: the processor in question. |
| * |
| * Return: The idle task for the CPU @cpu. |
| */ |
| struct task_struct *idle_task(int cpu) |
| { |
| return cpu_rq(cpu)->idle; |
| } |
| |
| /** |
| * find_process_by_pid - find a process with a matching PID value. |
| * @pid: the pid in question. |
| * |
| * The task of @pid, if found. %NULL otherwise. |
| */ |
| static struct task_struct *find_process_by_pid(pid_t pid) |
| { |
| return pid ? find_task_by_vpid(pid) : current; |
| } |
| |
| /* |
| * sched_setparam() passes in -1 for its policy, to let the functions |
| * it calls know not to change it. |
| */ |
| #define SETPARAM_POLICY -1 |
| |
| static void __setscheduler_params(struct task_struct *p, |
| const struct sched_attr *attr) |
| { |
| int policy = attr->sched_policy; |
| |
| if (policy == SETPARAM_POLICY) |
| policy = p->policy; |
| |
| p->policy = policy; |
| |
| if (dl_policy(policy)) |
| __setparam_dl(p, attr); |
| else if (fair_policy(policy)) |
| p->static_prio = NICE_TO_PRIO(attr->sched_nice); |
| |
| /* |
| * __sched_setscheduler() ensures attr->sched_priority == 0 when |
| * !rt_policy. Always setting this ensures that things like |
| * getparam()/getattr() don't report silly values for !rt tasks. |
| */ |
| p->rt_priority = attr->sched_priority; |
| p->normal_prio = normal_prio(p); |
| set_load_weight(p, true); |
| } |
| |
| /* Actually do priority change: must hold pi & rq lock. */ |
| static void __setscheduler(struct rq *rq, struct task_struct *p, |
| const struct sched_attr *attr, bool keep_boost) |
| { |
| /* |
| * If params can't change scheduling class changes aren't allowed |
| * either. |
| */ |
| if (attr->sched_flags & SCHED_FLAG_KEEP_PARAMS) |
| return; |
| |
| __setscheduler_params(p, attr); |
| |
| /* |
| * Keep a potential priority boosting if called from |
| * sched_setscheduler(). |
| */ |
| p->prio = normal_prio(p); |
| if (keep_boost) |
| p->prio = rt_effective_prio(p, p->prio); |
| |
| if (dl_prio(p->prio)) |
| p->sched_class = &dl_sched_class; |
| else if (rt_prio(p->prio)) |
| p->sched_class = &rt_sched_class; |
| else |
| p->sched_class = &fair_sched_class; |
| } |
| |
| /* |
| * Check the target process has a UID that matches the current process's: |
| */ |
| static bool check_same_owner(struct task_struct *p) |
| { |
| const struct cred *cred = current_cred(), *pcred; |
| bool match; |
| |
| rcu_read_lock(); |
| pcred = __task_cred(p); |
| match = (uid_eq(cred->euid, pcred->euid) || |
| uid_eq(cred->euid, pcred->uid)); |
| rcu_read_unlock(); |
| return match; |
| } |
| |
| static int __sched_setscheduler(struct task_struct *p, |
| const struct sched_attr *attr, |
| bool user, bool pi) |
| { |
| int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : |
| MAX_RT_PRIO - 1 - attr->sched_priority; |
| int retval, oldprio, oldpolicy = -1, queued, running; |
| int new_effective_prio, policy = attr->sched_policy; |
| const struct sched_class *prev_class; |
| struct rq_flags rf; |
| int reset_on_fork; |
| int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| struct rq *rq; |
| |
| /* The pi code expects interrupts enabled */ |
| BUG_ON(pi && in_interrupt()); |
| 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_FLAG_RESET_ON_FORK); |
| |
| if (!valid_policy(policy)) |
| return -EINVAL; |
| } |
| |
| if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV)) |
| return -EINVAL; |
| |
| /* |
| * Valid priorities for SCHED_FIFO and SCHED_RR are |
| * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, |
| * SCHED_BATCH and SCHED_IDLE is 0. |
| */ |
| if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || |
| (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) |
| return -EINVAL; |
| if ((dl_policy(policy) && !__checkparam_dl(attr)) || |
| (rt_policy(policy) != (attr->sched_priority != 0))) |
| return -EINVAL; |
| |
| /* |
| * Allow unprivileged RT tasks to decrease priority: |
| */ |
| if (user && !capable(CAP_SYS_NICE)) { |
| if (fair_policy(policy)) { |
| if (attr->sched_nice < task_nice(p) && |
| !can_nice(p, attr->sched_nice)) |
| return -EPERM; |
| } |
| |
| if (rt_policy(policy)) { |
| unsigned long rlim_rtprio = |
| task_rlimit(p, RLIMIT_RTPRIO); |
| |
| /* Can't set/change the rt policy: */ |
| if (policy != p->policy && !rlim_rtprio) |
| return -EPERM; |
| |
| /* Can't increase priority: */ |
| if (attr->sched_priority > p->rt_priority && |
| attr->sched_priority > rlim_rtprio) |
| return -EPERM; |
| } |
| |
| /* |
| * Can't set/change SCHED_DEADLINE policy at all for now |
| * (safest behavior); in the future we would like to allow |
| * unprivileged DL tasks to increase their relative deadline |
| * or reduce their runtime (both ways reducing utilization) |
| */ |
| if (dl_policy(policy)) |
| return -EPERM; |
| |
| /* |
| * Treat SCHED_IDLE as nice 20. Only allow a switch to |
| * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. |
| */ |
| if (task_has_idle_policy(p) && !idle_policy(policy)) { |
| if (!can_nice(p, task_nice(p))) |
| return -EPERM; |
| } |
| |
| /* Can't change other user's priorities: */ |
| if (!check_same_owner(p)) |
| return -EPERM; |
| |
| /* Normal users shall not reset the sched_reset_on_fork flag: */ |
| if (p->sched_reset_on_fork && !reset_on_fork) |
| return -EPERM; |
| } |
| |
| if (user) { |
| if (attr->sched_flags & SCHED_FLAG_SUGOV) |
| return -EINVAL; |
| |
| retval = security_task_setscheduler(p); |
| if (retval) |
| return retval; |
| } |
| |
| /* Update task specific "requested" clamps */ |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) { |
| retval = uclamp_validate(p, attr); |
| if (retval) |
| return retval; |
| } |
| |
| if (pi) |
| cpuset_read_lock(); |
| |
| /* |
| * Make sure no PI-waiters arrive (or leave) while we are |
| * changing the priority of the task: |
| * |
| * To be able to change p->policy safely, the appropriate |
| * runqueue lock must be held. |
| */ |
| rq = task_rq_lock(p, &rf); |
| update_rq_clock(rq); |
| |
| /* |
| * 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, |
| * but store a possible modification of reset_on_fork. |
| */ |
| if (unlikely(policy == p->policy)) { |
| if (fair_policy(policy) && attr->sched_nice != task_nice(p)) |
| goto change; |
| if (rt_policy(policy) && attr->sched_priority != p->rt_priority) |
| goto change; |
| if (dl_policy(policy) && dl_param_changed(p, attr)) |
| goto change; |
| if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) |
| goto change; |
| |
| p->sched_reset_on_fork = reset_on_fork; |
| retval = 0; |
| goto unlock; |
| } |
| change: |
| |
| if (user) { |
| #ifdef CONFIG_RT_GROUP_SCHED |
| /* |
| * Do not allow realtime tasks into groups that have no runtime |
| * assigned. |
| */ |
| if (rt_bandwidth_enabled() && rt_policy(policy) && |
| task_group(p)->rt_bandwidth.rt_runtime == 0 && |
| !task_group_is_autogroup(task_group(p))) { |
| retval = -EPERM; |
| goto unlock; |
| } |
| #endif |
| #ifdef CONFIG_SMP |
| if (dl_bandwidth_enabled() && dl_policy(policy) && |
| !(attr->sched_flags & SCHED_FLAG_SUGOV)) { |
| cpumask_t *span = rq->rd->span; |
| |
| /* |
| * Don't allow tasks with an affinity mask smaller than |
| * the entire root_domain to become SCHED_DEADLINE. We |
| * will also fail if there's no bandwidth available. |
| */ |
| if (!cpumask_subset(span, p->cpus_ptr) || |
| rq->rd->dl_bw.bw == 0) { |
| retval = -EPERM; |
| goto unlock; |
| } |
| } |
| #endif |
| } |
| |
| /* Re-check policy now with rq lock held: */ |
| if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { |
| policy = oldpolicy = -1; |
| task_rq_unlock(rq, p, &rf); |
| if (pi) |
| cpuset_read_unlock(); |
| goto recheck; |
| } |
| |
| /* |
| * If setscheduling to SCHED_DEADLINE (or changing the parameters |
| * of a SCHED_DEADLINE task) we need to check if enough bandwidth |
| * is available. |
| */ |
| if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) { |
| retval = -EBUSY; |
| goto unlock; |
| } |
| |
| p->sched_reset_on_fork = reset_on_fork; |
| oldprio = p->prio; |
| |
| 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. |
| */ |
| new_effective_prio = rt_effective_prio(p, newprio); |
| if (new_effective_prio == oldprio) |
| queue_flags &= ~DEQUEUE_MOVE; |
| } |
| |
| queued = task_on_rq_queued(p); |
| running = task_current(rq, p); |
| if (queued) |
| dequeue_task(rq, p, queue_flags); |
| if (running) |
| put_prev_task(rq, p); |
| |
| prev_class = p->sched_class; |
| |
| __setscheduler(rq, p, attr, pi); |
| __setscheduler_uclamp(p, attr); |
| |
| if (queued) { |
| /* |
| * We enqueue to tail when the priority of a task is |
| * increased (user space view). |
| */ |
| if (oldprio < p->prio) |
| queue_flags |= ENQUEUE_HEAD; |
| |
| enqueue_task(rq, p, queue_flags); |
| } |
| if (running) |
| set_next_task(rq, p); |
| |
| check_class_changed(rq, p, prev_class, oldprio); |
| |
| /* Avoid rq from going away on us: */ |
| preempt_disable(); |
| task_rq_unlock(rq, p, &rf); |
| |
| if (pi) { |
| cpuset_read_unlock(); |
| rt_mutex_adjust_pi(p); |
| } |
| |
| /* Run balance callbacks after we've adjusted the PI chain: */ |
| balance_callback(rq); |
| preempt_enable(); |
| |
| return 0; |
| |
| unlock: |
| task_rq_unlock(rq, p, &rf); |
| if (pi) |
| cpuset_read_unlock(); |
| return retval; |
| } |
| |
| static int _sched_setscheduler(struct task_struct *p, int policy, |
| const struct sched_param *param, bool check) |
| { |
| struct sched_attr attr = { |
| .sched_policy = policy, |
| .sched_priority = param->sched_priority, |
| .sched_nice = PRIO_TO_NICE(p->static_prio), |
| }; |
| |
| /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ |
| if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { |
| attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
| policy &= ~SCHED_RESET_ON_FORK; |
| attr.sched_policy = policy; |
| } |
| |
| return __sched_setscheduler(p, &attr, check, true); |
| } |
| /** |
| * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. |
| * @p: the task in question. |
| * @policy: new policy. |
| * @param: structure containing the new RT priority. |
| * |
| * Return: 0 on success. An error code otherwise. |
| * |
| * NOTE that the task may be already dead. |
| */ |
| int sched_setscheduler(struct task_struct *p, int policy, |
| const struct sched_param *param) |
| { |
| return _sched_setscheduler(p, policy, param, true); |
| } |
| EXPORT_SYMBOL_GPL(sched_setscheduler); |
| |
| int sched_setattr(struct task_struct *p, const struct sched_attr *attr) |
| { |
| return __sched_setscheduler(p, attr, true, true); |
| } |
| EXPORT_SYMBOL_GPL(sched_setattr); |
| |
| int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr) |
| { |
| return __sched_setscheduler(p, attr, false, true); |
| } |
| |
| /** |
| * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. |
| * @p: the task in question. |
| * @policy: new policy. |
| * @param: structure containing the new RT priority. |
| * |
| * Just like sched_setscheduler, only don't bother checking if the |
| * current context has permission. For example, this is needed in |
| * stop_machine(): we create temporary high priority worker threads, |
| * but our caller might not have that capability. |
| * |
| * Return: 0 on success. An error code otherwise. |
| */ |
| int sched_setscheduler_nocheck(struct task_struct *p, int policy, |
| const struct sched_param *param) |
| { |
| return _sched_setscheduler(p, policy, param, false); |
| } |
| EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); |
| |
| static int |
| do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) |
| { |
| struct sched_param lparam; |
| struct task_struct *p; |
| int retval; |
| |
| if (!param || pid < 0) |
| return -EINVAL; |
| if (copy_from_user(&lparam, param, sizeof(struct sched_param))) |
| return -EFAULT; |
| |
| rcu_read_lock(); |
| retval = -ESRCH; |
| p = find_process_by_pid(pid); |
| if (likely(p)) |
| get_task_struct(p); |
| rcu_read_unlock(); |
| |
| if (likely(p)) { |
| retval = sched_setscheduler(p, policy, &lparam); |
| put_task_struct(p); |
| } |
| |
| return retval; |
| } |
| |
| /* |
| * Mimics kernel/events/core.c perf_copy_attr(). |
| */ |
| static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) |
| { |
| u32 size; |
| int ret; |
| |
| /* Zero the full structure, so that a short copy will be nice: */ |
| memset(attr, 0, sizeof(*attr)); |
| |
| ret = get_user(size, &uattr->size); |
| if (ret) |
| return ret; |
| |
| /* ABI compatibility quirk: */ |
| if (!size) |
| size = SCHED_ATTR_SIZE_VER0; |
| if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE) |
| goto err_size; |
| |
| ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size); |
| if (ret) { |
| if (ret == -E2BIG) |
| goto err_size; |
| return ret; |
| } |
| |
| if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) && |
| size < SCHED_ATTR_SIZE_VER1) |
| return -EINVAL; |
| |
| /* |
| * XXX: Do we want to be lenient like existing syscalls; or do we want |
| * to be strict and return an error on out-of-bounds values? |
| */ |
| attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); |
| |
| return 0; |
| |
| err_size: |
| put_user(sizeof(*attr), &uattr->size); |
| return -E2BIG; |
| } |
| |
| /** |
| * sys_sched_setscheduler - set/change the scheduler policy and RT priority |
| * @pid: the pid in question. |
| * @policy: new policy. |
| * @param: structure containing the new RT priority. |
| * |
| * Return: 0 on success. An error code otherwise. |
| */ |
| SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param) |
| { |
| if (policy < 0) |
| return -EINVAL; |
| |
| return do_sched_setscheduler(pid, policy, param); |
| } |
| |
| /** |
| * sys_sched_setparam - set/change the RT priority of a thread |
| * @pid: the pid in question. |
| * @param: structure containing the new RT priority. |
| * |
| * Return: 0 on success. An error code otherwise. |
| */ |
| SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) |
| { |
| return do_sched_setscheduler(pid, SETPARAM_POLICY, param); |
| } |
| |
| /** |
| * sys_sched_setattr - same as above, but with extended sched_attr |
| * @pid: the pid in question. |
| * @uattr: structure containing the extended parameters. |
| * @flags: for future extension. |
| */ |
| SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, |
| unsigned int, flags) |
| { |
| struct sched_attr attr; |
| struct task_struct *p; |
| int retval; |
| |
| if (!uattr || pid < 0 || flags) |
| return -EINVAL; |
| |
| retval = sched_copy_attr(uattr, &attr); |
| if (retval) |
| return retval; |
| |
| if ((int)attr.sched_policy < 0) |
| return -EINVAL; |
| if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY) |
| attr.sched_policy = SETPARAM_POLICY; |
| |
| rcu_read_lock(); |
| retval = -ESRCH; |
| p = find_process_by_pid(pid); |
| if (likely(p)) |
| get_task_struct(p); |
| rcu_read_unlock(); |
| |
| if (likely(p)) { |
| retval = sched_setattr(p, &attr); |
| put_task_struct(p); |
| } |
| |
| return retval; |
| } |
| |
| /** |
| * sys_sched_getscheduler - get the policy (scheduling class) of a thread |
| * @pid: the pid in question. |
| * |
| * Return: On success, the policy of the thread. Otherwise, a negative error |
| * code. |
| */ |
| SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) |
| { |
| struct task_struct *p; |
| int retval; |
| |
| if (pid < 0) |
| return -EINVAL; |
| |
| retval = -ESRCH; |
| rcu_read_lock(); |
| p = find_process_by_pid(pid); |
| if (p) { |
| retval = security_task_getscheduler(p); |
| if (!retval) |
| retval = p->policy |
| | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); |
| } |
| rcu_read_unlock(); |
| return retval; |
| } |
| |
| /** |
| * sys_sched_getparam - get the RT priority of a thread |
| * @pid: the pid in question. |
| * @param: structure containing the RT priority. |
| * |
| * Return: On success, 0 and the RT priority is in @param. Otherwise, an error |
| * code. |
| */ |
| SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) |
| { |
| struct sched_param lp = { .sched_priority = 0 }; |
| struct task_struct *p; |
| int retval; |
| |
| if (!param || pid < 0) |
| return -EINVAL; |
| |
| rcu_read_lock(); |
| p = find_process_by_pid(pid); |
| retval = -ESRCH; |
| if (!p) |
| goto out_unlock; |
| |
| retval = security_task_getscheduler(p); |
| if (retval) |
| goto out_unlock; |
| |
| if (task_has_rt_policy(p)) |
| lp.sched_priority = p->rt_priority; |
| rcu_read_unlock(); |
| |
| /* |
| * This one might sleep, we cannot do it with a spinlock held ... |
| */ |
| retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; |
| |
| return retval; |
| |
| out_unlock: |
| rcu_read_unlock(); |
| return retval; |
| } |
| |
| /* |
| * Copy the kernel size attribute structure (which might be larger |
| * than what user-space knows about) to user-space. |
| * |
| * Note that all cases are valid: user-space buffer can be larger or |
| * smaller than the kernel-space buffer. The usual case is that both |
| * have the same size. |
| */ |
| static int |
| sched_attr_copy_to_user(struct sched_attr __user *uattr, |
| struct sched_attr *kattr, |
| unsigned int usize) |
| { |
| unsigned int ksize = sizeof(*kattr); |
| |
| if (!access_ok(uattr, usize)) |
| return -EFAULT; |
| |
| /* |
| * sched_getattr() ABI forwards and backwards compatibility: |
| * |
| * If usize == ksize then we just copy everything to user-space and all is good. |
| * |
| * If usize < ksize then we only copy as much as user-space has space for, |
| * this keeps ABI compatibility as well. We skip the rest. |
| * |
| * If usize > ksize then user-space is using a newer version of the ABI, |
| * which part the kernel doesn't know about. Just ignore it - tooling can |
| * detect the kernel's knowledge of attributes from the attr->size value |
| * which is set to ksize in this case. |
| */ |
| kattr->size = min(usize, ksize); |
| |
| if (copy_to_user(uattr, kattr, kattr->size)) |
| return -EFAULT; |
| |
| return 0; |
| } |
| |
| /** |
| * sys_sched_getattr - similar to sched_getparam, but with sched_attr |
| * @pid: the pid in question. |
| * @uattr: structure containing the extended parameters. |
| * @usize: sizeof(attr) for fwd/bwd comp. |
| * @flags: for future extension. |
| */ |
| SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, |
| unsigned int, usize, unsigned int, flags) |
| { |
| struct sched_attr kattr = { }; |
| struct task_struct *p; |
| int retval; |
| |
| if (!uattr || pid < 0 || usize > PAGE_SIZE || |
| usize < SCHED_ATTR_SIZE_VER0 || flags) |
| return -EINVAL; |
| |
| rcu_read_lock(); |
| p = find_process_by_pid(pid); |
| retval = -ESRCH; |
| if (!p) |
| goto out_unlock; |
| |
| retval = security_task_getscheduler(p); |
| if (retval) |
| goto out_unlock; |
| |
| kattr.sched_policy = p->policy; |
| if (p->sched_reset_on_fork) |
| kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
| if (task_has_dl_policy(p)) |
| __getparam_dl(p, &kattr); |
| else if (task_has_rt_policy(p)) |
| kattr.sched_priority = p->rt_priority; |
| else |
| kattr.sched_nice = task_nice(p); |
| |
| #ifdef CONFIG_UCLAMP_TASK |
| kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value; |
| kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value; |
| #endif |
| |
| rcu_read_unlock(); |
| |
| return sched_attr_copy_to_user(uattr, &kattr, usize); |
| |
| out_unlock: |
| rcu_read_unlock(); |
| return retval; |
| } |
| |
| long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) |
| { |
| cpumask_var_t cpus_allowed, new_mask; |
| struct task_struct *p; |
| int retval; |
| |
| rcu_read_lock(); |
| |
| p = find_process_by_pid(pid); |
| if (!p) { |
| rcu_read_unlock(); |
| return -ESRCH; |
| } |
| |
| /* Prevent p going away */ |
| get_task_struct(p); |
| rcu_read_unlock(); |
| |
| if (p->flags & PF_NO_SETAFFINITY) { |
| retval = -EINVAL; |
| goto out_put_task; |
| } |
| if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { |
| retval = -ENOMEM; |
| goto out_put_task; |
| } |
| if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { |
| retval = -ENOMEM; |
| goto out_free_cpus_allowed; |
| } |
| retval = -EPERM; |
| if (!check_same_owner(p)) { |
| rcu_read_lock(); |
| if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { |
| rcu_read_unlock(); |
| goto out_free_new_mask; |
| } |
| rcu_read_unlock(); |
| } |
| |
| retval = security_task_setscheduler(p); |
| if (retval) |
| goto out_free_new_mask; |
| |
| |
| cpuset_cpus_allowed(p, cpus_allowed); |
| cpumask_and(new_mask, in_mask, cpus_allowed); |
| |
| /* |
| * Since bandwidth control happens on root_domain basis, |
| * if admission test is enabled, we only admit -deadline |
| * tasks allowed to run on all the CPUs in the task's |
| * root_domain. |
| */ |
| #ifdef CONFIG_SMP |
| if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { |
| rcu_read_lock(); |
| if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { |
| retval = -EBUSY; |
| rcu_read_unlock(); |
| goto out_free_new_mask; |
| } |
| rcu_read_unlock(); |
| } |
| #endif |
| again: |
| retval = __set_cpus_allowed_ptr(p, new_mask, true); |
| |
| if (!retval) { |
| cpuset_cpus_allowed(p, cpus_allowed); |
| if (!cpumask_subset(new_mask, cpus_allowed)) { |
| /* |
| * We must have raced with a concurrent cpuset |
| * update. Just reset the cpus_allowed to the |
| * cpuset's cpus_allowed |
| */ |
| cpumask_copy(new_mask, cpus_allowed); |
| goto again; |
| } |
| } |
| out_free_new_mask: |
| free_cpumask_var(new_mask); |
| out_free_cpus_allowed: |
| free_cpumask_var(cpus_allowed); |
| out_put_task: |
| put_task_struct(p); |
| return retval; |
| } |
| |
| static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, |
| struct cpumask *new_mask) |
| { |
| if (len < cpumask_size()) |
| cpumask_clear(new_mask); |
| else if (len > cpumask_size()) |
| len = cpumask_size(); |
| |
| return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; |
| } |
| |
| /** |
| * sys_sched_setaffinity - set the CPU affinity of a process |
| * @pid: pid of the process |
| * @len: length in bytes of the bitmask pointed to by user_mask_ptr |
| * @user_mask_ptr: user-space pointer to the new CPU mask |
| * |
| * Return: 0 on success. An error code otherwise. |
| */ |
| SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, |
| unsigned long __user *, user_mask_ptr) |
| { |
| cpumask_var_t new_mask; |
| int retval; |
| |
| if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) |
| return -ENOMEM; |
| |
| retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); |
| if (retval == 0) |
| retval = sched_setaffinity(pid, new_mask); |
| free_cpumask_var(new_mask); |
| return retval; |
| } |
| |
| long sched_getaffinity(pid_t pid, struct cpumask *mask) |
| { |
| struct task_struct *p; |
| unsigned long flags; |
| int retval; |
| |
| rcu_read_lock(); |
| |
| retval = -ESRCH; |
| p = find_process_by_pid(pid); |
| if (!p) |
| goto out_unlock; |
| |
| retval = security_task_getscheduler(p); |
| if (retval) |
| goto out_unlock; |
| |
| raw_spin_lock_irqsave(&p->pi_lock, flags); |
| cpumask_and(mask, &p->cpus_mask, cpu_active_mask); |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| |
| out_unlock: |
| rcu_read_unlock(); |
| |
| return retval; |
| } |
| |
| /** |
| * sys_sched_getaffinity - get the CPU affinity of a process |
| * @pid: pid of the process |
| * @len: length in bytes of the bitmask pointed to by user_mask_ptr |
| * @user_mask_ptr: user-space pointer to hold the current CPU mask |
| * |
| * Return: size of CPU mask copied to user_mask_ptr on success. An |
| * error code otherwise. |
| */ |
| SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, |
| unsigned long __user *, user_mask_ptr) |
| { |
| int ret; |
| cpumask_var_t mask; |
| |
| if ((len * BITS_PER_BYTE) < nr_cpu_ids) |
| return -EINVAL; |
| if (len & (sizeof(unsigned long)-1)) |
| return -EINVAL; |
| |
| if (!alloc_cpumask_var(&mask, GFP_KERNEL)) |
| return -ENOMEM; |
| |
| ret = sched_getaffinity(pid, mask); |
| if (ret == 0) { |
| unsigned int retlen = min(len, cpumask_size()); |
| |
| if (copy_to_user(user_mask_ptr, mask, retlen)) |
| ret = -EFAULT; |
| else |
| ret = retlen; |
| } |
| free_cpumask_var(mask); |
| |
| return ret; |
| } |
| |
| /** |
| * sys_sched_yield - yield the current processor to other threads. |
| * |
| * This function yields the current CPU to other tasks. If there are no |
| * other threads running on this CPU then this function will return. |
| * |
| * Return: 0. |
| */ |
| static void do_sched_yield(void) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| rq = this_rq_lock_irq(&rf); |
| |
| schedstat_inc(rq->yld_count); |
| current->sched_class->yield_task(rq); |
| |
| /* |
| * Since we are going to call schedule() anyway, there's |
| * no need to preempt or enable interrupts: |
| */ |
| preempt_disable(); |
| rq_unlock(rq, &rf); |
| sched_preempt_enable_no_resched(); |
| |
| schedule(); |
| } |
| |
| SYSCALL_DEFINE0(sched_yield) |
| { |
| do_sched_yield(); |
| return 0; |
| } |
| |
| #ifndef CONFIG_PREEMPTION |
| int __sched _cond_resched(void) |
| { |
| if (should_resched(0)) { |
| preempt_schedule_common(); |
| return 1; |
| } |
| rcu_all_qs(); |
| return 0; |
| } |
| EXPORT_SYMBOL(_cond_resched); |
| #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 (resched) |
| preempt_schedule_common(); |
| else |
| cpu_relax(); |
| ret = 1; |
| spin_lock(lock); |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(__cond_resched_lock); |
| |
| /** |
| * yield - yield the current processor to other threads. |
| * |
| * Do not ever use this function, there's a 99% chance you're doing it wrong. |
| * |
| * The scheduler is at all times free to pick the calling task as the most |
| * eligible task to run, if removing the yield() call from your code breaks |
| * it, its already broken. |
| * |
| * Typical broken usage is: |
| * |
| * while (!event) |
| * yield(); |
| * |
| * where one assumes that yield() will let 'the other' process run that will |
| * make event true. If the current task is a SCHED_FIFO task that will never |
| * happen. Never use yield() as a progress guarantee!! |
| * |
| * If you want to use yield() to wait for something, use wait_event(). |
| * If you want to use yield() to be 'nice' for others, use cond_resched(). |
| * If you still want to use yield(), do not! |
| */ |
| void __sched yield(void) |
| { |
| set_current_state(TASK_RUNNING); |
| do_sched_yield(); |
| } |
| EXPORT_SYMBOL(yield); |
| |
| /** |
| * yield_to - yield the current processor to another thread in |
| * your thread group, or accelerate that thread toward the |
| * processor it's on. |
| * @p: target task |
| * @preempt: whether task preemption is allowed or not |
| * |
| * It's the caller's job to ensure that the target task struct |
| * can't go away on us before we can do any checks. |
| * |
| * Return: |
| * true (>0) if we indeed boosted the target task. |
| * false (0) if we failed to boost the target. |
| * -ESRCH if there's no task to yield to. |
| */ |
| int __sched yield_to(struct task_struct *p, bool preempt) |
| { |
| struct task_struct *curr = current; |
| struct rq *rq, *p_rq; |
| unsigned long flags; |
| int yielded = 0; |
| |
| local_irq_save(flags); |
| rq = this_rq(); |
| |
| again: |
| p_rq = task_rq(p); |
| /* |
| * If we're the only runnable task on the rq and target rq also |
| * has only one task, there's absolutely no point in yielding. |
| */ |
| if (rq->nr_running == 1 && p_rq->nr_running == 1) { |
| yielded = -ESRCH; |
| goto out_irq; |
| } |
| |
| double_rq_lock(rq, p_rq); |
| if (task_rq(p) != p_rq) { |
| double_rq_unlock(rq, p_rq); |
| goto again; |
| } |
| |
| if (!curr->sched_class->yield_to_task) |
| goto out_unlock; |
| |
| if (curr->sched_class != p->sched_class) |
| goto out_unlock; |
| |
| if (task_running(p_rq, p) || p->state) |
| goto out_unlock; |
| |
| yielded = curr->sched_class->yield_to_task(rq, p, preempt); |
| if (yielded) { |
| schedstat_inc(rq->yld_count); |
| /* |
| * Make p's CPU reschedule; pick_next_entity takes care of |
| * fairness. |
| */ |
| if (preempt && rq != p_rq) |
| resched_curr(p_rq); |
| } |
| |
| out_unlock: |
| double_rq_unlock(rq, p_rq); |
| out_irq: |
| local_irq_restore(flags); |
| |
| if (yielded > 0) |
| schedule(); |
| |
| return yielded; |
| } |
| EXPORT_SYMBOL_GPL(yield_to); |
| |
| int io_schedule_prepare(void) |
| { |
| int old_iowait = current->in_iowait; |
| |
| current->in_iowait = 1; |
| blk_schedule_flush_plug(current); |
| |
| 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. |
| */ |
| 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); |
| |
| /** |
| * sys_sched_get_priority_max - return maximum RT priority. |
| * @policy: scheduling class. |
| * |
| * Return: On success, this syscall returns the maximum |
| * rt_priority that can be used by a given scheduling class. |
| * On failure, a negative error code is returned. |
| */ |
| SYSCALL_DEFINE1(sched_get_priority_max, int, policy) |
| { |
| int ret = -EINVAL; |
| |
| switch (policy) { |
| case SCHED_FIFO: |
| case SCHED_RR: |
| ret = MAX_USER_RT_PRIO-1; |
| break; |
| case SCHED_DEADLINE: |
| case SCHED_NORMAL: |
| case SCHED_BATCH: |
| case SCHED_IDLE: |
| ret = 0; |
| break; |
| } |
| return ret; |
| } |
| |
| /** |
| * sys_sched_get_priority_min - return minimum RT priority. |
| * @policy: scheduling class. |
| * |
| * Return: On success, this syscall returns the minimum |
| * rt_priority that can be used by a given scheduling class. |
| * On failure, a negative error code is returned. |
| */ |
| SYSCALL_DEFINE1(sched_get_priority_min, int, policy) |
| { |
| int ret = -EINVAL; |
| |
| switch (policy) { |
| case SCHED_FIFO: |
| case SCHED_RR: |
| ret = 1; |
| break; |
| case SCHED_DEADLINE: |
| case SCHED_NORMAL: |
| case SCHED_BATCH: |
| case SCHED_IDLE: |
| ret = 0; |
| } |
| return ret; |
| } |
| |
| static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) |
| { |
| struct task_struct *p; |
| unsigned int time_slice; |
| struct rq_flags rf; |
| struct rq *rq; |
| int retval; |
| |
| if (pid < 0) |
| return -EINVAL; |
| |
| retval = -ESRCH; |
| rcu_read_lock(); |
| p = find_process_by_pid(pid); |
| if (!p) |
| goto out_unlock; |
| |
| retval = security_task_getscheduler(p); |
| if (retval) |
| goto out_unlock; |
| |
| rq = task_rq_lock(p, &rf); |
| time_slice = 0; |
| if (p->sched_class->get_rr_interval) |
| time_slice = p->sched_class->get_rr_interval(rq, p); |
| task_rq_unlock(rq, p, &rf); |
| |
| rcu_read_unlock(); |
| jiffies_to_timespec64(time_slice, t); |
| return 0; |
| |
| out_unlock: |
| rcu_read_unlock(); |
| return retval; |
| } |
| |
| /** |
| * sys_sched_rr_get_interval - return the default timeslice of a process. |
| * @pid: pid of the process. |
| * @interval: userspace pointer to the timeslice value. |
| * |
| * this syscall writes the default timeslice value of a given process |
| * into the user-space timespec buffer. A value of '0' means infinity. |
| * |
| * Return: On success, 0 and the timeslice is in @interval. Otherwise, |
| * an error code. |
| */ |
| SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, |
| struct __kernel_timespec __user *, interval) |
| { |
| struct timespec64 t; |
| int retval = sched_rr_get_interval(pid, &t); |
| |
| if (retval == 0) |
| retval = put_timespec64(&t, interval); |
| |
| return retval; |
| } |
| |
| #ifdef CONFIG_COMPAT_32BIT_TIME |
| SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid, |
| struct old_timespec32 __user *, interval) |
| { |
| struct timespec64 t; |
| int retval = sched_rr_get_interval(pid, &t); |
| |
| if (retval == 0) |
| retval = put_old_timespec32(&t, interval); |
| return retval; |
| } |
| #endif |
| |
| void sched_show_task(struct task_struct *p) |
| { |
| unsigned long free = 0; |
| int ppid; |
| |
| if (!try_get_task_stack(p)) |
| return; |
| |
| printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p)); |
| |
| if (p->state == TASK_RUNNING) |
| printk(KERN_CONT " running task "); |
| #ifdef CONFIG_DEBUG_STACK_USAGE |
| free = stack_not_used(p); |
| #endif |
| ppid = 0; |
| rcu_read_lock(); |
| if (pid_alive(p)) |
| ppid = task_pid_nr(rcu_dereference(p->real_parent)); |
| rcu_read_unlock(); |
| printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, |
| task_pid_nr(p), ppid, |
| (unsigned long)task_thread_info(p)->flags); |
| |
| print_worker_info(KERN_INFO, p); |
| show_stack(p, NULL); |
| put_task_stack(p); |
| } |
| EXPORT_SYMBOL_GPL(sched_show_task); |
| |
| static inline bool |
| state_filter_match(unsigned long state_filter, struct task_struct *p) |
| { |
| /* no filter, everything matches */ |
| if (!state_filter) |
| return true; |
| |
| /* filter, but doesn't match */ |
| if (!(p->state & state_filter)) |
| return false; |
| |
| /* |
| * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows |
| * TASK_KILLABLE). |
| */ |
| if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE) |
| return false; |
| |
| return true; |
| } |
| |
| |
| void show_state_filter(unsigned long state_filter) |
| { |
| struct task_struct *g, *p; |
| |
| #if BITS_PER_LONG == 32 |
| printk(KERN_INFO |
| " task PC stack pid father\n"); |
| #else |
| printk(KERN_INFO |
| " task PC stack pid father\n"); |
| #endif |
| 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 |
| 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(); |
| } |
| |
| /** |
| * 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_idle(struct task_struct *idle, int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long flags; |
| |
| __sched_fork(0, idle); |
| |
| raw_spin_lock_irqsave(&idle->pi_lock, flags); |
| raw_spin_lock(&rq->lock); |
| |
| idle->state = TASK_RUNNING; |
| idle->se.exec_start = sched_clock(); |
| idle->flags |= PF_IDLE; |
| |
| kasan_unpoison_task_stack(idle); |
| |
| #ifdef CONFIG_SMP |
| /* |
| * Its possible that init_idle() gets called multiple times on a task, |
| * in that case do_set_cpus_allowed() will not do the right thing. |
| * |
| * And since this is boot we can forgo the serialization. |
| */ |
| set_cpus_allowed_common(idle, cpumask_of(cpu)); |
| #endif |
| /* |
| * We're having a chicken and egg problem, even though we are |
| * holding rq->lock, the CPU isn't yet set to this CPU so the |
| * lockdep check in task_group() will fail. |
| * |
| * Similar case to sched_fork(). / Alternatively we could |
| * use task_rq_lock() here and obtain the other rq->lock. |
| * |
| * 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_rq = TASK_ON_RQ_QUEUED; |
| #ifdef CONFIG_SMP |
| idle->on_cpu = 1; |
| #endif |
| 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); |
| |
| /* |
| * The idle tasks have their own, simple scheduling class: |
| */ |
| idle->sched_class = &idle_sched_class; |
| 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 *cur, |
| const struct cpumask *trial) |
| { |
| int ret = 1; |
| |
| if (!cpumask_weight(cur)) |
| return ret; |
| |
| ret = dl_cpuset_cpumask_can_shrink(cur, trial); |
| |
| return ret; |
| } |
| |
| int task_can_attach(struct task_struct *p, |
| const struct cpumask *cs_cpus_allowed) |
| { |
| 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; |
| goto out; |
| } |
| |
| if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, |
| cs_cpus_allowed)) |
| ret = dl_task_can_attach(p, cs_cpus_allowed); |
| |
| out: |
| return ret; |
| } |
| |
| bool sched_smp_initialized __read_mostly; |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| /* Migrate current task p to target_cpu */ |
| int migrate_task_to(struct task_struct *p, int target_cpu) |
| { |
| struct migration_arg arg = { p, target_cpu }; |
| int curr_cpu = task_cpu(p); |
| |
| if (curr_cpu == target_cpu) |
| return 0; |
| |
| if (!cpumask_test_cpu(target_cpu, p->cpus_ptr)) |
| return -EINVAL; |
| |
| /* TODO: This is not properly updating schedstats */ |
| |
| trace_sched_move_numa(p, curr_cpu, target_cpu); |
| return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); |
| } |
| |
| /* |
| * Requeue a task on a given node and accurately track the number of NUMA |
| * tasks on the runqueues |
| */ |
| void sched_setnuma(struct task_struct *p, int nid) |
| { |
| bool queued, running; |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| rq = task_rq_lock(p, &rf); |
| queued = task_on_rq_queued(p); |
| running = task_current(rq, p); |
| |
| if (queued) |
| dequeue_task(rq, p, DEQUEUE_SAVE); |
| if (running) |
| put_prev_task(rq, p); |
| |
| p->numa_preferred_nid = nid; |
| |
| if (queued) |
| enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| if (running) |
| set_next_task(rq, p); |
| task_rq_unlock(rq, p, &rf); |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| #ifdef CONFIG_HOTPLUG_CPU |
| /* |
| * Ensure 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(cpu_online(smp_processor_id())); |
| |
| if (mm != &init_mm) { |
| switch_mm(mm, &init_mm, current); |
| current->active_mm = &init_mm; |
| finish_arch_post_lock_switch(); |
| } |
| mmdrop(mm); |
| } |
| |
| /* |
| * Since this CPU is going 'away' for a while, fold any nr_active delta |
| * we might have. Assumes we're called after migrate_tasks() so that the |
| * nr_active count is stable. We need to take the teardown 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 struct task_struct *__pick_migrate_task(struct rq *rq) |
| { |
| const struct sched_class *class; |
| struct task_struct *next; |
| |
| for_each_class(class) { |
| next = class->pick_next_task(rq); |
| if (next) { |
| next->sched_class->put_prev_task(rq, next); |
| return next; |
| } |
| } |
| |
| /* The idle class should always have a runnable task */ |
| BUG(); |
| } |
| |
| /* |
| * Migrate all tasks from the rq, sleeping tasks will be migrated by |
| * try_to_wake_up()->select_task_rq(). |
| * |
| * Called with rq->lock held even though we'er in stop_machine() and |
| * there's no concurrency possible, we hold the required locks anyway |
| * because of lock validation efforts. |
| */ |
| static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf) |
| { |
| struct rq *rq = dead_rq; |
| struct task_struct *next, *stop = rq->stop; |
| struct rq_flags orf = *rf; |
| int dest_cpu; |
| |
| /* |
| * Fudge the rq selection such that the below task selection loop |
| * doesn't get stuck on the currently eligible stop task. |
| * |
| * We're currently inside stop_machine() and the rq is either stuck |
| * in the stop_machine_cpu_stop() loop, or we're executing this code, |
| * either way we should never end up calling schedule() until we're |
| * done here. |
| */ |
| rq->stop = NULL; |
| |
| /* |
| * put_prev_task() and pick_next_task() sched |
| * class method both need to have an up-to-date |
| * value of rq->clock[_task] |
| */ |
| update_rq_clock(rq); |
| |
| for (;;) { |
| /* |
| * There's this thread running, bail when that's the only |
| * remaining thread: |
| */ |
| if (rq->nr_running == 1) |
| break; |
| |
| next = __pick_migrate_task(rq); |
| |
| /* |
| * Rules for changing task_struct::cpus_mask are holding |
| * both pi_lock and rq->lock, such that holding either |
| * stabilizes the mask. |
| * |
| * Drop rq->lock is not quite as disastrous as it usually is |
| * because !cpu_active at this point, which means load-balance |
| * will not interfere. Also, stop-machine. |
| */ |
| rq_unlock(rq, rf); |
| raw_spin_lock(&next->pi_lock); |
| rq_relock(rq, rf); |
| |
| /* |
| * Since we're inside stop-machine, _nothing_ should have |
| * changed the task, WARN if weird stuff happened, because in |
| * that case the above rq->lock drop is a fail too. |
| */ |
| if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { |
| raw_spin_unlock(&next->pi_lock); |
| continue; |
| } |
| |
| /* Find suitable destination for @next, with force if needed. */ |
| dest_cpu = select_fallback_rq(dead_rq->cpu, next); |
| rq = __migrate_task(rq, rf, next, dest_cpu); |
| if (rq != dead_rq) { |
| rq_unlock(rq, rf); |
| rq = dead_rq; |
| *rf = orf; |
| rq_relock(rq, rf); |
| } |
| raw_spin_unlock(&next->pi_lock); |
| } |
| |
| rq->stop = stop; |
| } |
| #endif /* CONFIG_HOTPLUG_CPU */ |
| |
| void set_rq_online(struct rq *rq) |
| { |
| if (!rq->online) { |
| const struct sched_class *class; |
| |
| cpumask_set_cpu(rq->cpu, rq->rd->online); |
| rq->online = 1; |
| |
| for_each_class(class) { |
| if (class->rq_online) |
| class->rq_online(rq); |
| } |
| } |
| } |
| |
| void set_rq_offline(struct rq *rq) |
| { |
| if (rq->online) { |
| const struct sched_class *class; |
| |
| for_each_class(class) { |
| if (class->rq_offline) |
| class->rq_offline(rq); |
| } |
| |
| cpumask_clear_cpu(rq->cpu, rq->rd->online); |
| rq->online = 0; |
| } |
| } |
| |
| /* |
| * 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) { |
| if (dl_cpu_busy(cpu)) |
| return -EBUSY; |
| cpuset_update_active_cpus(); |
| } else { |
| num_cpus_frozen++; |
| partition_sched_domains(1, NULL, NULL); |
| } |
| return 0; |
| } |
| |
| int sched_cpu_activate(unsigned int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct rq_flags rf; |
| |
| #ifdef CONFIG_SCHED_SMT |
| /* |
| * When going up, increment the number of cores with SMT present. |
| */ |
| if (cpumask_weight(cpu_smt_mask(cpu)) == 2) |
| static_branch_inc_cpuslocked(&sched_smt_present); |
| #endif |
| set_cpu_active(cpu, true); |
| |
| if (sched_smp_initialized) { |
| sched_domains_numa_masks_set(cpu); |
| 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. |
| */ |
| rq_lock_irqsave(rq, &rf); |
| if (rq->rd) { |
| BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); |
| set_rq_online(rq); |
| } |
| rq_unlock_irqrestore(rq, &rf); |
| |
| return 0; |
| } |
| |
| int sched_cpu_deactivate(unsigned int cpu) |
| { |
| int ret; |
| |
| set_cpu_active(cpu, false); |
| /* |
| * 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. |
| * |
| * Do sync before park smpboot threads to take care the rcu boost case. |
| */ |
| synchronize_rcu(); |
| |
| #ifdef CONFIG_SCHED_SMT |
| /* |
| * When going down, decrement the number of cores with SMT present. |
| */ |
| if (cpumask_weight(cpu_smt_mask(cpu)) == 2) |
| static_branch_dec_cpuslocked(&sched_smt_present); |
| #endif |
| |
| if (!sched_smp_initialized) |
| return 0; |
| |
| ret = cpuset_cpu_inactive(cpu); |
| if (ret) { |
| set_cpu_active(cpu, true); |
| return ret; |
| } |
| sched_domains_numa_masks_clear(cpu); |
| return 0; |
| } |
| |
| static void sched_rq_cpu_starting(unsigned int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| rq->calc_load_update = calc_load_update; |
| update_max_interval(); |
| } |
| |
| int sched_cpu_starting(unsigned int cpu) |
| { |
| sched_rq_cpu_starting(cpu); |
| sched_tick_start(cpu); |
| return 0; |
| } |
| |
| #ifdef CONFIG_HOTPLUG_CPU |
| int sched_cpu_dying(unsigned int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct rq_flags rf; |
| |
| /* Handle pending wakeups and then migrate everything off */ |
| sched_ttwu_pending(); |
| sched_tick_stop(cpu); |
| |
| rq_lock_irqsave(rq, &rf); |
| if (rq->rd) { |
| BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); |
| set_rq_offline(rq); |
| } |
| migrate_tasks(rq, &rf); |
| BUG_ON(rq->nr_running != 1); |
| rq_unlock_irqrestore(rq, &rf); |
| |
| calc_load_migrate(rq); |
| update_max_interval(); |
| nohz_balance_exit_idle(rq); |
| hrtick_clear(rq); |
| return 0; |
| } |
| #endif |
| |
| void __init sched_init_smp(void) |
| { |
| sched_init_numa(); |
| |
| /* |
| * There's no userspace yet to cause hotplug operations; hence all the |
| * CPU masks are stable and all blatant races in the below code cannot |
| * happen. |
| */ |
| mutex_lock(&sched_domains_mutex); |
| sched_init_domains(cpu_active_mask); |
| mutex_unlock(&sched_domains_mutex); |
| |
| /* Move init over to a non-isolated CPU */ |
| if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0) |
| BUG(); |
| sched_init_granularity(); |
| |
| init_sched_rt_class(); |
| init_sched_dl_class(); |
| |
| 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) |
| { |
| sched_init_granularity(); |
| } |
| #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 __read_mostly; |
| #endif |
| |
| DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); |
| DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); |
| |
| void __init sched_init(void) |
| { |
| unsigned long ptr = 0; |
| int i; |
| |
| wait_bit_init(); |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| ptr += 2 * nr_cpu_ids * sizeof(void **); |
| #endif |
| #ifdef CONFIG_RT_GROUP_SCHED |
| ptr += 2 * nr_cpu_ids * sizeof(void **); |
| #endif |
| if (ptr) { |
| ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT); |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| root_task_group.se = (struct sched_entity **)ptr; |
| ptr += nr_cpu_ids * sizeof(void **); |
| |
| root_task_group.cfs_rq = (struct cfs_rq **)ptr; |
| ptr += nr_cpu_ids * sizeof(void **); |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| #ifdef CONFIG_RT_GROUP_SCHED |
| root_task_group.rt_se = (struct sched_rt_entity **)ptr; |
| ptr += nr_cpu_ids * sizeof(void **); |
| |
| root_task_group.rt_rq = (struct rt_rq **)ptr; |
| ptr += nr_cpu_ids * sizeof(void **); |
| |
| #endif /* CONFIG_RT_GROUP_SCHED */ |
| } |
| #ifdef CONFIG_CPUMASK_OFFSTACK |
| for_each_possible_cpu(i) { |
| per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( |
| cpumask_size(), GFP_KERNEL, cpu_to_node(i)); |
| per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( |
| cpumask_size(), GFP_KERNEL, cpu_to_node(i)); |
| } |
| #endif /* CONFIG_CPUMASK_OFFSTACK */ |
| |
| init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); |
| init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime()); |
| |
| #ifdef CONFIG_SMP |
| init_defrootdomain(); |
| #endif |
| |
| #ifdef CONFIG_RT_GROUP_SCHED |
| init_rt_bandwidth(&root_task_group.rt_bandwidth, |
| global_rt_period(), global_rt_runtime()); |
| #endif /* CONFIG_RT_GROUP_SCHED */ |
| |
| #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); |
| autogroup_init(&init_task); |
| #endif /* CONFIG_CGROUP_SCHED */ |
| |
| for_each_possible_cpu(i) { |
| struct rq *rq; |
| |
| rq = cpu_rq(i); |
| raw_spin_lock_init(&rq->lock); |
| rq->nr_running = 0; |
| rq->calc_load_active = 0; |
| rq->calc_load_update = jiffies + LOAD_FREQ; |
| init_cfs_rq(&rq->cfs); |
| init_rt_rq(&rq->rt); |
| init_dl_rq(&rq->dl); |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| root_task_group.shares = ROOT_TASK_GROUP_LOAD; |
| INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); |
| rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; |
| /* |
| * How much CPU bandwidth does root_task_group get? |
| * |
| * In case of task-groups formed thr' the cgroup filesystem, it |
| * gets 100% of the CPU resources in the system. This overall |
| * system CPU resource is divided among the tasks of |
| * root_task_group and its child task-groups in a fair manner, |
| * based on each entity's (task or task-group's) weight |
| * (se->load.weight). |
| * |
| * In other words, if root_task_group has 10 tasks of weight |
| * 1024) and two child groups A0 and A1 (of weight 1024 each), |
| * then A0's share of the CPU resource is: |
| * |
| * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% |
| * |
| * We achieve this by letting root_task_group's tasks sit |
| * directly in rq->cfs (i.e root_task_group->se[] = NULL). |
| */ |
| init_cfs_bandwidth(&root_task_group.cfs_bandwidth); |
| init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; |
| #ifdef CONFIG_RT_GROUP_SCHED |
| init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); |
| #endif |
| #ifdef CONFIG_SMP |
| rq->sd = NULL; |
| rq->rd = NULL; |
| rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; |
| rq->balance_callback = NULL; |
| rq->active_balance = 0; |
| rq->next_balance = jiffies; |
| rq->push_cpu = 0; |
| rq->cpu = i; |
| rq->online = 0; |
| rq->idle_stamp = 0; |
| rq->avg_idle = 2*sysctl_sched_migration_cost; |
| rq->max_idle_balance_cost = sysctl_sched_migration_cost; |
| |
| INIT_LIST_HEAD(&rq->cfs_tasks); |
| |
| rq_attach_root(rq, &def_root_domain); |
| #ifdef CONFIG_NO_HZ_COMMON |
| rq->last_load_update_tick = jiffies; |
| rq->last_blocked_load_update_tick = jiffies; |
| atomic_set(&rq->nohz_flags, 0); |
| #endif |
| #endif /* CONFIG_SMP */ |
| hrtick_rq_init(rq); |
| atomic_set(&rq->nr_iowait, 0); |
| } |
| |
| set_load_weight(&init_task, false); |
| |
| /* |
| * The boot idle thread does lazy MMU switching as well: |
| */ |
| mmgrab(&init_mm); |
| enter_lazy_tlb(&init_mm, 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". |
| */ |
| init_idle(current, smp_processor_id()); |
| |
| calc_load_update = jiffies + LOAD_FREQ; |
| |
| #ifdef CONFIG_SMP |
| idle_thread_set_boot_cpu(); |
| #endif |
| init_sched_fair_class(); |
| |
| init_schedstats(); |
| |
| psi_init(); |
| |
| init_uclamp(); |
| |
| scheduler_running = 1; |
| } |
| |
| #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
| static inline int preempt_count_equals(int preempt_offset) |
| { |
| int nested = preempt_count() + rcu_preempt_depth(); |
| |
| return (nested == preempt_offset); |
| } |
| |
| void __might_sleep(const char *file, int line, int preempt_offset) |
| { |
| /* |
| * 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(current->state != TASK_RUNNING && current->task_state_change, |
| "do not call blocking ops when !TASK_RUNNING; " |
| "state=%lx set at [<%p>] %pS\n", |
| current->state, |
| (void *)current->task_state_change, |
| (void *)current->task_state_change); |
| |
| ___might_sleep(file, line, preempt_offset); |
| } |
| EXPORT_SYMBOL(__might_sleep); |
| |
| void ___might_sleep(const char *file, int line, int preempt_offset) |
| { |
| /* 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 ((preempt_count_equals(preempt_offset) && !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); |
| |
| printk(KERN_ERR |
| "BUG: sleeping function called from invalid context at %s:%d\n", |
| file, line); |
| printk(KERN_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); |
| |
| if (task_stack_end_corrupted(current)) |
| printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); |
| |
| debug_show_held_locks(current); |
| if (irqs_disabled()) |
| print_irqtrace_events(current); |
| if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
| && !preempt_count_equals(preempt_offset)) { |
| pr_err("Preemption disabled at:"); |
| print_ip_sym(preempt_disable_ip); |
| pr_cont("\n"); |
| } |
| dump_stack(); |
| add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
| } |
| EXPORT_SYMBOL(___might_sleep); |
| |
| 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); |
| #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; |
| |
| p->se.exec_start = 0; |
| schedstat_set(p->se.statistics.wait_start, 0); |
| schedstat_set(p->se.statistics.sleep_start, 0); |
| schedstat_set(p->se.statistics.block_start, 0); |
| |
| if (!dl_task(p) && !rt_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_IA64) || defined(CONFIG_KGDB_KDB) |
| /* |
| * These functions are only useful for the IA64 MCA handling, or 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_IA64) || defined(CONFIG_KGDB_KDB) */ |
| |
| #ifdef CONFIG_IA64 |
| /** |
| * ia64_set_curr_task - set the current task for a given CPU. |
| * @cpu: the processor in question. |
| * @p: the task pointer to set. |
| * |
| * Description: This function must only be used when non-maskable interrupts |
| * are serviced on a separate stack. It allows the architecture to switch the |
| * notion of the current task on a CPU in a non-blocking manner. This function |
| * must be called with all CPU's synchronized, and interrupts disabled, the |
| * and caller must save the original value of the current task (see |
| * curr_task() above) and restore that value before reenabling interrupts and |
| * re-starting the system. |
| * |
| * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! |
| */ |
| void ia64_set_curr_task(int cpu, struct task_struct *p) |
| { |
| cpu_curr(cpu) = p; |
| } |
| |
| #endif |
| |
| #ifdef CONFIG_CGROUP_SCHED |
| /* task_group_lock serializes the addition/removal of task groups */ |
| static DEFINE_SPINLOCK(task_group_lock); |
| |
| static inline void alloc_uclamp_sched_group(struct task_group *tg, |
| struct task_group *parent) |
| { |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| enum uclamp_id clamp_id; |
| |
| for_each_clamp_id(clamp_id) { |
| uclamp_se_set(&tg->uclamp_req[clamp_id], |
| uclamp_none(clamp_id), false); |
| tg->uclamp[clamp_id] = parent->uclamp[clamp_id]; |
| } |
| #endif |
| } |
| |
| static void sched_free_group(struct task_group *tg) |
| { |
| free_fair_sched_group(tg); |
| free_rt_sched_group(tg); |
| autogroup_free(tg); |
| kmem_cache_free(task_group_cache, tg); |
| } |
| |
| /* 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); |
| |
| if (!alloc_fair_sched_group(tg, parent)) |
| goto err; |
| |
| if (!alloc_rt_sched_group(tg, parent)) |
| goto err; |
| |
| alloc_uclamp_sched_group(tg, parent); |
| |
| return tg; |
| |
| err: |
| sched_free_group(tg); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| void sched_online_group(struct task_group *tg, struct task_group *parent) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&task_group_lock, flags); |
| list_add_rcu(&tg->list, &task_groups); |
| |
| /* Root should already exist: */ |
| WARN_ON(!parent); |
| |
| tg->parent = parent; |
| INIT_LIST_HEAD(&tg->children); |
| list_add_rcu(&tg->siblings, &parent->children); |
| spin_unlock_irqrestore(&task_group_lock, flags); |
| |
| online_fair_sched_group(tg); |
| } |
| |
| /* rcu callback to free various structures associated with a task group */ |
| static void sched_free_group_rcu(struct rcu_head *rhp) |
| { |
| /* Now it should be safe to free those cfs_rqs: */ |
| sched_free_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_free_group_rcu); |
| } |
| |
| void sched_offline_group(struct task_group *tg) |
| { |
| unsigned long flags; |
| |
| /* End participation in shares distribution: */ |
| unregister_fair_sched_group(tg); |
| |
| spin_lock_irqsave(&task_group_lock, flags); |
| list_del_rcu(&tg->list); |
| list_del_rcu(&tg->siblings); |
| spin_unlock_irqrestore(&task_group_lock, flags); |
| } |
| |
| static void sched_change_group(struct task_struct *tsk, int type) |
| { |
| struct task_group *tg; |
| |
| /* |
| * All callers are synchronized by task_rq_lock(); we do not use RCU |
| * which is pointless here. Thus, we pass "true" to task_css_check() |
| * to prevent lockdep warnings. |
| */ |
| tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), |
| struct task_group, css); |
| tg = autogroup_task_group(tsk, tg); |
| tsk->sched_task_group = tg; |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| if (tsk->sched_class->task_change_group) |
| tsk->sched_class->task_change_group(tsk, type); |
| else |
| #endif |
| set_task_rq(tsk, task_cpu(tsk)); |
| } |
| |
| /* |
| * Change task's runqueue when it moves between groups. |
| * |
| * The caller of this function should have put the task in its new group by |
| * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect |
| * its new group. |
| */ |
| void sched_move_task(struct task_struct *tsk) |
| { |
| int queued, running, queue_flags = |
| DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| rq = task_rq_lock(tsk, &rf); |
| update_rq_clock(rq); |
| |
| running = task_current(rq, tsk); |
| queued = task_on_rq_queued(tsk); |
| |
| if (queued) |
| dequeue_task(rq, tsk, queue_flags); |
| if (running) |
| put_prev_task(rq, tsk); |
| |
| sched_change_group(tsk, TASK_MOVE_GROUP); |
| |
| if (queued) |
| enqueue_task(rq, tsk, queue_flags); |
| if (running) |
| set_next_task(rq, tsk); |
| |
| task_rq_unlock(rq, tsk, &rf); |
| } |
| |
| 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); |
| |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| /* Propagate the effective uclamp value for the new group */ |
| cpu_util_update_eff(css); |
| #endif |
| |
| return 0; |
| } |
| |
| static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) |
| { |
| struct task_group *tg = css_tg(css); |
| |
| sched_offline_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_free_group(tg); |
| } |
| |
| /* |
| * This is called before wake_up_new_task(), therefore we really only |
| * have to set its group bits, all the other stuff does not apply. |
| */ |
| static void cpu_cgroup_fork(struct task_struct *task) |
| { |
| struct rq_flags rf; |
| struct rq *rq; |
| |
| rq = task_rq_lock(task, &rf); |
| |
| update_rq_clock(rq); |
| sched_change_group(task, TASK_SET_GROUP); |
| |
| task_rq_unlock(rq, task, &rf); |
| } |
| |
| static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) |
| { |
| struct task_struct *task; |
| struct cgroup_subsys_state *css; |
| int ret = 0; |
| |
| cgroup_taskset_for_each(task, css, tset) { |
| #ifdef CONFIG_RT_GROUP_SCHED |
| if (!sched_rt_can_attach(css_tg(css), task)) |
| return -EINVAL; |
| #endif |
| /* |
| * Serialize against wake_up_new_task() such that if its |
| * running, we're sure to observe its full state. |
| */ |
| raw_spin_lock_irq(&task->pi_lock); |
| /* |
| * Avoid calling sched_move_task() before wake_up_new_task() |
| * has happened. This would lead to problems with PELT, due to |
| * move wanting to detach+attach while we're not attached yet. |
| */ |
| if (task->state == TASK_NEW) |
| ret = -EINVAL; |
| raw_spin_unlock_irq(&task->pi_lock); |
| |
| if (ret) |
| break; |
| } |
| return ret; |
| } |
| |
| static void cpu_cgroup_attach(struct cgroup_taskset *tset) |
| { |
| struct task_struct *task; |
| struct cgroup_subsys_state *css; |
| |
| cgroup_taskset_for_each(task, css, tset) |
| sched_move_task(task); |
| } |
| |
| #ifdef CONFIG_UCLAMP_TASK_GROUP |
| static void cpu_util_update_eff(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys_state *top_css = css; |
| struct uclamp_se *uc_parent = NULL; |
| struct uclamp_se *uc_se = NULL; |
| unsigned int eff[UCLAMP_CNT]; |
| enum uclamp_id clamp_id; |
| unsigned int clamps; |
| |
| css_for_each_descendant_pre(css, top_css) { |
| uc_parent = css_tg(css)->parent |
| ? css_tg(css)->parent->uclamp : NULL; |
| |
| for_each_clamp_id(clamp_id) { |
| /* Assume effective clamps matches requested clamps */ |
| eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value; |
| /* Cap effective clamps with parent's effective clamps */ |
| if (uc_parent && |
| eff[clamp_id] > uc_parent[clamp_id].value) { |
| eff[clamp_id] = uc_parent[clamp_id].value; |
| } |
| } |
| /* Ensure protection is always capped by limit */ |
| eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]); |
| |
| /* Propagate most restrictive effective clamps */ |
| clamps = 0x0; |
| uc_se = css_tg(css)->uclamp; |
| for_each_clamp_id(clamp_id) { |
| if (eff[clamp_id] == uc_se[clamp_id].value) |
| continue; |
| uc_se[clamp_id].value = eff[clamp_id]; |
| uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]); |
| clamps |= (0x1 << clamp_id); |
| } |
| if (!clamps) { |
| css = css_rightmost_descendant(css); |
| continue; |
| } |
| |
| /* Immediately update descendants RUNNABLE tasks */ |
| uclamp_update_active_tasks(css, clamps); |
| } |
| } |
| |
| /* |
| * Integer 10^N with a given N exponent by casting to integer the literal "1eN" |
| * C expression. Since there is no way to convert a macro argument (N) into a |
| * character constant, use two levels of macros. |
| */ |
| #define _POW10(exp) ((unsigned int)1e##exp) |
| #define POW10(exp) _POW10(exp) |
| |
| struct uclamp_request { |
| #define UCLAMP_PERCENT_SHIFT 2 |
| #define UCLAMP_PERCENT_SCALE (100 * POW10(UCLAMP_PERCENT_SHIFT)) |
| s64 percent; |
| u64 util; |
| int ret; |
| }; |
| |
| static inline struct uclamp_request |
| capacity_from_percent(char *buf) |
| { |
| struct uclamp_request req = { |
| .percent = UCLAMP_PERCENT_SCALE, |
| .util = SCHED_CAPACITY_SCALE, |
| .ret = 0, |
| }; |
| |
| buf = strim(buf); |
| if (strcmp(buf, "max")) { |
| req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT, |
| &req.percent); |
| if (req.ret) |
| return req; |
| if (req.percent > UCLAMP_PERCENT_SCALE) { |
| req.ret = -ERANGE; |
| return req; |
| } |
| |
| req.util = req.percent << SCHED_CAPACITY_SHIFT; |
| req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE); |
| } |
| |
| return req; |
| } |
| |
| static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf, |
| size_t nbytes, loff_t off, |
| enum uclamp_id clamp_id) |
| { |
| struct uclamp_request req; |
| struct task_group *tg; |
| |
| req = capacity_from_percent(buf); |
| if (req.ret) |
| return req.ret; |
| |
| mutex_lock(&uclamp_mutex); |
| rcu_read_lock(); |
| |
| tg = css_tg(of_css(of)); |
| if (tg->uclamp_req[clamp_id].value != req.util) |
| uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false); |
| |
| /* |
| * Because of not recoverable conversion rounding we keep track of the |
| * exact requested value |
| */ |
| tg->uclamp_pct[clamp_id] = req.percent; |
| |
| /* Update effective clamps to track the most restrictive value */ |
| cpu_util_update_eff(of_css(of)); |
| |
| rcu_read_unlock(); |
| mutex_unlock(&uclamp_mutex); |
| |
| return nbytes; |
| } |
| |
| static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, |
| loff_t off) |
| { |
| return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN); |
| } |
| |
| static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, |
| loff_t off) |
| { |
| return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX); |
| } |
| |
| static inline void cpu_uclamp_print(struct seq_file *sf, |
| enum uclamp_id clamp_id) |
| { |
| struct task_group *tg; |
| u64 util_clamp; |
| u64 percent; |
| u32 rem; |
| |
| rcu_read_lock(); |
| tg = css_tg(seq_css(sf)); |
| util_clamp = tg->uclamp_req[clamp_id].value; |
| rcu_read_unlock(); |
| |
| if (util_clamp == SCHED_CAPACITY_SCALE) { |
| seq_puts(sf, "max\n"); |
| return; |
| } |
| |
| percent = tg->uclamp_pct[clamp_id]; |
| percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem); |
| seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem); |
| } |
| |
| static int cpu_uclamp_min_show(struct seq_file *sf, void *v) |
| { |
| cpu_uclamp_print(sf, UCLAMP_MIN); |
| return 0; |
| } |
| |
| static int cpu_uclamp_max_show(struct seq_file *sf, void *v) |
| { |
| cpu_uclamp_print(sf, UCLAMP_MAX); |
| return 0; |
| } |
| #endif /* CONFIG_UCLAMP_TASK_GROUP */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static int cpu_shares_write_u64(struct cgroup_subsys_state *css, |
| struct cftype *cftype, u64 shareval) |
| { |
| if (shareval > scale_load_down(ULONG_MAX)) |
| shareval = MAX_SHARES; |
| return sched_group_set_shares(css_tg(css), scale_load(shareval)); |
| } |
| |
| static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| struct task_group *tg = css_tg(css); |
| |
| return (u64) scale_load_down(tg->shares); |
| } |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| static DEFINE_MUTEX(cfs_constraints_mutex); |
| |
| const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ |
| static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ |
| |
| static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); |
| |
| static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) |
| { |
| int i, ret = 0, runtime_enabled, runtime_was_enabled; |
| struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| |
| if (tg == &root_task_group) |
| return -EINVAL; |
| |
| /* |
| * Ensure we have at some amount of bandwidth every period. This is |
| * to prevent reaching a state of large arrears when throttled via |
| * entity_tick() resulting in prolonged exit starvation. |
| */ |
| if (quota < min_cfs_quota_period || period < min_cfs_quota_period) |
| return -EINVAL; |
| |
| /* |
| * Likewise, bound things on the otherside by preventing insane quota |
| * periods. This also allows us to normalize in computing quota |
| * feasibility. |
| */ |
| if (period > max_cfs_quota_period) |
| return -EINVAL; |
| |
| /* |
| * Prevent race between setting of cfs_rq->runtime_enabled and |
| * unthrottle_offline_cfs_rqs(). |
| */ |
| get_online_cpus(); |
| mutex_lock(&cfs_constraints_mutex); |
| ret = __cfs_schedulable(tg, period, quota); |
| if (ret) |
| goto out_unlock; |
| |
| runtime_enabled = quota != RUNTIME_INF; |
| runtime_was_enabled = cfs_b->quota != RUNTIME_INF; |
| /* |
| * If we need to toggle cfs_bandwidth_used, off->on must occur |
| * before making related changes, and on->off must occur afterwards |
| */ |
| if (runtime_enabled && !runtime_was_enabled) |
| cfs_bandwidth_usage_inc(); |
| raw_spin_lock_irq(&cfs_b->lock); |
| cfs_b->period = ns_to_ktime(period); |
| cfs_b->quota = quota; |
| |
| __refill_cfs_bandwidth_runtime(cfs_b); |
| |
| /* Restart the period timer (if active) to handle new period expiry: */ |
| if (runtime_enabled) |
| start_cfs_bandwidth(cfs_b); |
| |
| raw_spin_unlock_irq(&cfs_b->lock); |
| |
| for_each_online_cpu(i) { |
| struct cfs_rq *cfs_rq = tg->cfs_rq[i]; |
| struct rq *rq = cfs_rq->rq; |
| struct rq_flags rf; |
| |
| rq_lock_irq(rq, &rf); |
| cfs_rq->runtime_enabled = runtime_enabled; |
| cfs_rq->runtime_remaining = 0; |
| |
| if (cfs_rq->throttled) |
| unthrottle_cfs_rq(cfs_rq); |
| rq_unlock_irq(rq, &rf); |
| } |
| if (runtime_was_enabled && !runtime_enabled) |
| cfs_bandwidth_usage_dec(); |
| out_unlock: |
| mutex_unlock(&cfs_constraints_mutex); |
| put_online_cpus(); |
| |
| return ret; |
| } |
| |
| static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) |
| { |
| u64 quota, period; |
| |
| period = ktime_to_ns(tg->cfs_bandwidth.period); |
| if (cfs_quota_us < 0) |
| quota = RUNTIME_INF; |
| else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC) |
| quota = (u64)cfs_quota_us * NSEC_PER_USEC; |
| else |
| return -EINVAL; |
| |
| return tg_set_cfs_bandwidth(tg, period, quota); |
| } |
| |
| static long tg_get_cfs_quota(struct task_group *tg) |
| { |
| u64 quota_us; |
| |
| if (tg->cfs_bandwidth.quota == RUNTIME_INF) |
| return -1; |
| |
| quota_us = tg->cfs_bandwidth.quota; |
| do_div(quota_us, NSEC_PER_USEC); |
| |
| return quota_us; |
| } |
| |
| static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) |
| { |
| u64 quota, period; |
| |
| if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC) |
| return -EINVAL; |
| |
| period = (u64)cfs_period_us * NSEC_PER_USEC; |
| quota = tg->cfs_bandwidth.quota; |
| |
| return tg_set_cfs_bandwidth(tg, period, quota); |
| } |
| |
| static long tg_get_cfs_period(struct task_group *tg) |
| { |
| u64 cfs_period_us; |
| |
| cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); |
| do_div(cfs_period_us, NSEC_PER_USEC); |
| |
| return cfs_period_us; |
| } |
| |
| static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return tg_get_cfs_quota(css_tg(css)); |
| } |
| |
| static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, |
| struct cftype *cftype, s64 cfs_quota_us) |
| { |
| return tg_set_cfs_quota(css_tg(css), cfs_quota_us); |
| } |
| |
| static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return tg_get_cfs_period(css_tg(css)); |
| } |
| |
| static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, |
| struct cftype *cftype, u64 cfs_period_us) |
| { |
| return tg_set_cfs_period(css_tg(css), cfs_period_us); |
| } |
| |
| struct cfs_schedulable_data { |
| struct task_group *tg; |
| u64 period, quota; |
| }; |
| |
| /* |
| * normalize group quota/period to be quota/max_period |
| * note: units are usecs |
| */ |
| static u64 normalize_cfs_quota(struct task_group *tg, |
| struct cfs_schedulable_data *d) |
| { |
| u64 quota, period; |
| |
| if (tg == d->tg) { |
| period = d->period; |
| quota = d->quota; |
| } else { |
| period = tg_get_cfs_period(tg); |
| quota = tg_get_cfs_quota(tg); |
| } |
| |
| /* note: these should typically be equivalent */ |
| if (quota == RUNTIME_INF || quota == -1) |
| return RUNTIME_INF; |
| |
| return to_ratio(period, quota); |
| } |
| |
| static int tg_cfs_schedulable_down(struct task_group *tg, void *data) |
| { |
| struct cfs_schedulable_data *d = data; |
| struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| s64 quota = 0, parent_quota = -1; |
| |
| if (!tg->parent) { |
| quota = RUNTIME_INF; |
| } else { |
| struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; |
| |
| quota = normalize_cfs_quota(tg, d); |
| parent_quota = parent_b->hierarchical_quota; |
| |
| /* |
| * Ensure max(child_quota) <= parent_quota. On cgroup2, |
| * always take the min. On cgroup1, only inherit when no |
| * limit is set: |
| */ |
| if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) { |
| quota = min(quota, parent_quota); |
| } else { |
| if (quota == RUNTIME_INF) |
| quota = parent_quota; |
| else if (parent_quota != RUNTIME_INF && quota > parent_quota) |
| return -EINVAL; |
| } |
| } |
| cfs_b->hierarchical_quota = quota; |
| |
| return 0; |
| } |
| |
| static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) |
| { |
| int ret; |
| struct cfs_schedulable_data data = { |
| .tg = tg, |
| .period = period, |
| .quota = quota, |
| }; |
| |
| if (quota != RUNTIME_INF) { |
| do_div(data.period, NSEC_PER_USEC); |
| do_div(data.quota, NSEC_PER_USEC); |
| } |
| |
| rcu_read_lock(); |
| ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| |
| static int cpu_cfs_stat_show(struct seq_file *sf, void *v) |
| { |
| struct task_group *tg = css_tg(seq_css(sf)); |
| struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| |
| seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); |
| seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); |
| seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); |
| |
| if (schedstat_enabled() && tg != &root_task_group) { |
| u64 ws = 0; |
| int i; |
| |
| for_each_possible_cpu(i) |
| ws += schedstat_val(tg->se[i]->statistics.wait_sum); |
| |
| seq_printf(sf, "wait_sum %llu\n", ws); |
| } |
| |
| return 0; |
| } |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| #ifdef CONFIG_RT_GROUP_SCHED |
| static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, |
| struct cftype *cft, s64 val) |
| { |
| return sched_group_set_rt_runtime(css_tg(css), val); |
| } |
| |
| static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return sched_group_rt_runtime(css_tg(css)); |
| } |
| |
| static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, |
| struct cftype *cftype, u64 rt_period_us) |
| { |
| return sched_group_set_rt_period(css_tg(css), rt_period_us); |
| } |
| |
| static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return sched_group_rt_period(css_tg(css)); |
| } |
| #endif /* CONFIG_RT_GROUP_SCHED */ |
| |
| static struct cftype cpu_legacy_files[] = { |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| { |
| .name = "shares", |
| .read_u64 = cpu_shares_read_u64, |
| .write_u64 = cpu_shares_write_u64, |
| }, |
| #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 = "stat", |
| .seq_show = cpu_cfs_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 */ |
| }; |
| |
| static int cpu_extra_stat_show(struct seq_file *sf, |
| struct cgroup_subsys_state *css) |
| { |
| #ifdef CONFIG_CFS_BANDWIDTH |
| { |
| struct task_group *tg = css_tg(css); |
| struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| u64 throttled_usec; |
| |
| throttled_usec = cfs_b->throttled_time; |
| do_div(throttled_usec, NSEC_PER_USEC); |
| |
| seq_printf(sf, "nr_periods %d\n" |
| "nr_throttled %d\n" |
| "throttled_usec %llu\n", |
| cfs_b->nr_periods, cfs_b->nr_throttled, |
| throttled_usec); |
| } |
| #endif |
| return 0; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| struct task_group *tg = css_tg(css); |
| u64 weight = scale_load_down(tg->shares); |
| |
| return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024); |
| } |
| |
| static int cpu_weight_write_u64(struct cgroup_subsys_state *css, |
| struct cftype *cft, u64 weight) |
| { |
| /* |
| * cgroup weight knobs should use the common MIN, DFL and MAX |
| * values which are 1, 100 and 10000 respectively. While it loses |
| * a bit of range on both ends, it maps pretty well onto the shares |
| * value used by scheduler and the round-trip conversions preserve |
| * the original value over the entire range. |
| */ |
| if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX) |
| return -ERANGE; |
| |
| weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL); |
| |
| return sched_group_set_shares(css_tg(css), scale_load(weight)); |
| } |
| |
| static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| unsigned long weight = scale_load_down(css_tg(css)->shares); |
| int last_delta = INT_MAX; |
| int prio, delta; |
| |
| /* find the closest nice value to the current weight */ |
| for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) { |
| delta = abs(sched_prio_to_weight[prio] - weight); |
| if (delta >= last_delta) |
| break; |
| last_delta = delta; |
| } |
| |
| return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO); |
| } |
| |
| static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css, |
| struct cftype *cft, s64 nice) |
| { |
| unsigned long weight; |
| int idx; |
| |
| if (nice < MIN_NICE || nice > MAX_NICE) |
| return -ERANGE; |
| |
| idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO; |
| idx = array_index_nospec(idx, 40); |
| weight = sched_prio_to_weight[idx]; |
| |
| return sched_group_set_shares(css_tg(css), scale_load(weight)); |
| } |
| #endif |
| |
| static void __maybe_unused cpu_period_quota_print(struct seq_file *sf, |
| long period, long quota) |
| { |
| if (quota < 0) |
| seq_puts(sf, "max"); |
| else |
| seq_printf(sf, "%ld", quota); |
| |
| seq_printf(sf, " %ld\n", period); |
| } |
| |
| /* caller should put the current value in *@periodp before calling */ |
| static int __maybe_unused cpu_period_quota_parse(char *buf, |
| u64 *periodp, u64 *quotap) |
| { |
| char tok[21]; /* U64_MAX */ |
| |
| if (sscanf(buf, "%20s %llu", tok, periodp) < 1) |
| return -EINVAL; |
| |
| *periodp *= NSEC_PER_USEC; |
| |
| if (sscanf(tok, "%llu", quotap)) |
| *quotap *= NSEC_PER_USEC; |
| else if (!strcmp(tok, "max")) |
| *quotap = RUNTIME_INF; |
| else |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| static int cpu_max_show(struct seq_file *sf, void *v) |
| { |
| struct task_group *tg = css_tg(seq_css(sf)); |
| |
| cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg)); |
| return 0; |
| } |
| |
| static ssize_t cpu_max_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| struct task_group *tg = css_tg(of_css(of)); |
| u64 period = tg_get_cfs_period(tg); |
| u64 quota; |
| int ret; |
| |
| ret = cpu_period_quota_parse(buf, &period, "a); |
| if (!ret) |
| ret = tg_set_cfs_bandwidth(tg, period, quota); |
| return ret ?: nbytes; |
| } |
| #endif |
| |
| static struct cftype cpu_files[] = { |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| { |
| .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, |
| }, |
| #endif |
| #ifdef CONFIG_CFS_BANDWIDTH |
| { |
| .name = "max", |
| .flags = CFTYPE_NOT_ON_ROOT, |
| .seq_show = cpu_max_show, |
| .write = cpu_max_write, |
| }, |
| #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 */ |
| }; |
| |
| 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, |
| .fork = cpu_cgroup_fork, |
| .can_attach = cpu_cgroup_can_attach, |
| .attach = cpu_cgroup_attach, |
| .legacy_cftypes = cpu_legacy_files, |
| .dfl_cftypes = cpu_files, |
| .early_init = true, |
| .threaded = true, |
| }; |
| |
| #endif /* CONFIG_CGROUP_SCHED */ |
| |
| void dump_cpu_task(int cpu) |
| { |
| pr_info("Task dump for CPU %d:\n", cpu); |
| sched_show_task(cpu_curr(cpu)); |
| } |
| |
| /* |
| * Nice levels are multiplicative, with a gentle 10% change for every |
| * nice level changed. I.e. when a CPU-bound task goes from nice 0 to |
| * nice 1, it will get ~10% less CPU time than another CPU-bound task |
| * that remained on nice 0. |
| * |
| * The "10% effect" is relative and cumulative: from _any_ nice level, |
| * if you go up 1 level, it's -10% CPU usage, if you go down 1 level |
| * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. |
| * If a task goes up by ~10% and another task goes down by ~10% then |
| * the relative distance between them is ~25%.) |
| */ |
| const int sched_prio_to_weight[40] = { |
| /* -20 */ 88761, 71755, 56483, 46273, 36291, |
| /* -15 */ 29154, 23254, 18705, 14949, 11916, |
| /* -10 */ 9548, 7620, 6100, 4904, 3906, |
| /* -5 */ 3121, 2501, 1991, 1586, 1277, |
| /* 0 */ 1024, 820, 655, 526, 423, |
| /* 5 */ 335, 272, 215, 172, 137, |
| /* 10 */ 110, 87, 70, 56, 45, |
| /* 15 */ 36, 29, 23, 18, 15, |
| }; |
| |
| /* |
| * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. |
| * |
| * In cases where the weight does not change often, we can use the |
| * precalculated inverse to speed up arithmetics by turning divisions |
| * into multiplications: |
| */ |
| const u32 sched_prio_to_wmult[40] = { |
| /* -20 */ 48388, 59856, 76040, 92818, 118348, |
| /* -15 */ 147320, 184698, 229616, 287308, 360437, |
| /* -10 */ 449829, 563644, 704093, 875809, 1099582, |
| /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, |
| /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, |
| /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, |
| /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, |
| /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, |
| }; |
| |
| #undef CREATE_TRACE_POINTS |