diff options
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 1874 |
1 files changed, 56 insertions, 1818 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 35a35e36024b..ae5ef3013a55 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2,9 +2,10 @@ /* * kernel/sched/core.c * - * Core kernel scheduler code and related syscalls + * Core kernel CPU scheduler code * * Copyright (C) 1991-2002 Linus Torvalds + * Copyright (C) 1998-2024 Ingo Molnar, Red Hat */ #include <linux/highmem.h> #include <linux/hrtimer_api.h> @@ -706,14 +707,14 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) /* * 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. + * {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 + * 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. @@ -825,7 +826,7 @@ static void __hrtick_start(void *arg) /* * Called to set the hrtick timer state. * - * called with rq->lock held and irqs disabled + * called with rq->lock held and IRQs disabled */ void hrtick_start(struct rq *rq, u64 delay) { @@ -849,7 +850,7 @@ void hrtick_start(struct rq *rq, u64 delay) /* * Called to set the hrtick timer state. * - * called with rq->lock held and irqs disabled + * called with rq->lock held and IRQs disabled */ void hrtick_start(struct rq *rq, u64 delay) { @@ -883,7 +884,7 @@ 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 + * try_cmpxchg based fetch_or() macro so it works for different integer types: */ #define fetch_or(ptr, mask) \ ({ \ @@ -1080,7 +1081,7 @@ void resched_cpu(int cpu) * * 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). + * (as that CPU's timer base may not be up to date wrt jiffies etc). */ int get_nohz_timer_target(void) { @@ -1140,7 +1141,7 @@ static void wake_up_idle_cpu(int cpu) * nohz functions that would need to follow TIF_NR_POLLING * clearing: * - * - On most archs, a simple fetch_or on ti::flags with a + * - On most architectures, a simple fetch_or on ti::flags with a * "0" value would be enough to know if an IPI needs to be sent. * * - x86 needs to perform a last need_resched() check between @@ -1323,30 +1324,27 @@ int tg_nop(struct task_group *tg, void *data) } #endif -static void set_load_weight(struct task_struct *p, bool update_load) +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; + struct load_weight lw; - /* - * SCHED_IDLE tasks get minimal weight: - */ if (task_has_idle_policy(p)) { - load->weight = scale_load(WEIGHT_IDLEPRIO); - load->inv_weight = WMULT_IDLEPRIO; - return; + lw.weight = scale_load(WEIGHT_IDLEPRIO); + lw.inv_weight = WMULT_IDLEPRIO; + } else { + lw.weight = scale_load(sched_prio_to_weight[prio]); + lw.inv_weight = sched_prio_to_wmult[prio]; } /* * 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]; - } + if (update_load && p->sched_class == &fair_sched_class) + reweight_task(p, &lw); + else + p->se.load = lw; } #ifdef CONFIG_UCLAMP_TASK @@ -1383,7 +1381,7 @@ static unsigned int __maybe_unused sysctl_sched_uclamp_util_max = SCHED_CAPACITY * This knob will not override the system default sched_util_clamp_min defined * above. */ -static unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE; +unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE; /* All clamps are required to be less or equal than these values */ static struct uclamp_se uclamp_default[UCLAMP_CNT]; @@ -1408,32 +1406,6 @@ static struct uclamp_se uclamp_default[UCLAMP_CNT]; */ DEFINE_STATIC_KEY_FALSE(sched_uclamp_used); -/* 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 min_t(unsigned int, clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1); -} - -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) @@ -1675,7 +1647,7 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, rq_clamp = uclamp_rq_get(rq, clamp_id); /* * Defensive programming: this should never happen. If it happens, - * e.g. due to future modification, warn and fixup the expected value. + * e.g. due to future modification, warn and fix up the expected value. */ SCHED_WARN_ON(bucket->value > rq_clamp); if (bucket->value >= rq_clamp) { @@ -1897,107 +1869,6 @@ undo: } #endif -static int uclamp_validate(struct task_struct *p, - const struct sched_attr *attr) -{ - int util_min = p->uclamp_req[UCLAMP_MIN].value; - int util_max = p->uclamp_req[UCLAMP_MAX].value; - - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) { - util_min = attr->sched_util_min; - - if (util_min + 1 > SCHED_CAPACITY_SCALE + 1) - return -EINVAL; - } - - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { - util_max = attr->sched_util_max; - - if (util_max + 1 > SCHED_CAPACITY_SCALE + 1) - return -EINVAL; - } - - if (util_min != -1 && util_max != -1 && util_min > util_max) - return -EINVAL; - - /* - * We have valid uclamp attributes; make sure uclamp is enabled. - * - * We need to do that here, because enabling static branches is a - * blocking operation which obviously cannot be done while holding - * scheduler locks. - */ - static_branch_enable(&sched_uclamp_used); - - return 0; -} - -static bool uclamp_reset(const struct sched_attr *attr, - enum uclamp_id clamp_id, - struct uclamp_se *uc_se) -{ - /* Reset on sched class change for a non user-defined clamp value. */ - if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)) && - !uc_se->user_defined) - return true; - - /* Reset on sched_util_{min,max} == -1. */ - if (clamp_id == UCLAMP_MIN && - attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN && - attr->sched_util_min == -1) { - return true; - } - - if (clamp_id == UCLAMP_MAX && - attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX && - attr->sched_util_max == -1) { - return true; - } - - return false; -} - -static void __setscheduler_uclamp(struct task_struct *p, - const struct sched_attr *attr) -{ - enum uclamp_id clamp_id; - - for_each_clamp_id(clamp_id) { - struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; - unsigned int value; - - if (!uclamp_reset(attr, clamp_id, uc_se)) - continue; - - /* - * RT by default have a 100% boost value that could be modified - * at runtime. - */ - if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) - value = sysctl_sched_uclamp_util_min_rt_default; - else - value = uclamp_none(clamp_id); - - uclamp_se_set(uc_se, value, false); - - } - - if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) - return; - - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN && - attr->sched_util_min != -1) { - uclamp_se_set(&p->uclamp_req[UCLAMP_MIN], - attr->sched_util_min, true); - } - - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX && - attr->sched_util_max != -1) { - 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; @@ -2065,13 +1936,6 @@ static void __init init_uclamp(void) #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 uclamp_post_fork(struct task_struct *p) { } static inline void init_uclamp(void) { } @@ -2101,7 +1965,7 @@ unsigned long get_wchan(struct task_struct *p) return ip; } -static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) +void enqueue_task(struct rq *rq, struct task_struct *p, int flags) { if (!(flags & ENQUEUE_NOCLOCK)) update_rq_clock(rq); @@ -2118,7 +1982,7 @@ static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) sched_core_enqueue(rq, p); } -static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) +void dequeue_task(struct rq *rq, struct task_struct *p, int flags) { if (sched_core_enabled(rq)) sched_core_dequeue(rq, p, flags); @@ -2156,52 +2020,6 @@ void deactivate_task(struct rq *rq, struct task_struct *p, int flags) dequeue_task(rq, p, flags); } -static inline int __normal_prio(int policy, int rt_prio, int nice) -{ - int prio; - - if (dl_policy(policy)) - prio = MAX_DL_PRIO - 1; - else if (rt_policy(policy)) - prio = MAX_RT_PRIO - 1 - rt_prio; - else - prio = NICE_TO_PRIO(nice); - - return 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) -{ - return __normal_prio(p->policy, p->rt_priority, PRIO_TO_NICE(p->static_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. @@ -2220,9 +2038,9 @@ inline int task_curr(const struct task_struct *p) * 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) +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) @@ -2391,9 +2209,6 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state static void __do_set_cpus_allowed(struct task_struct *p, struct affinity_context *ctx); -static int __set_cpus_allowed_ptr(struct task_struct *p, - struct affinity_context *ctx); - static void migrate_disable_switch(struct rq *rq, struct task_struct *p) { struct affinity_context ac = { @@ -2408,7 +2223,7 @@ static void migrate_disable_switch(struct rq *rq, struct task_struct *p) return; /* - * Violates locking rules! see comment in __do_set_cpus_allowed(). + * Violates locking rules! See comment in __do_set_cpus_allowed(). */ __do_set_cpus_allowed(p, &ac); } @@ -2575,7 +2390,7 @@ static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, } /* - * migration_cpu_stop - this will be executed by a highprio stopper thread + * migration_cpu_stop - this will be executed by a high-prio stopper thread * and performs thread migration by bumping thread off CPU then * 'pushing' onto another runqueue. */ @@ -2820,16 +2635,6 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) kfree_rcu((union cpumask_rcuhead *)ac.user_mask, rcu); } -static cpumask_t *alloc_user_cpus_ptr(int node) -{ - /* - * See do_set_cpus_allowed() above for the rcu_head usage. - */ - int size = max_t(int, cpumask_size(), sizeof(struct rcu_head)); - - return kmalloc_node(size, GFP_KERNEL, node); -} - int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, int node) { @@ -3198,8 +3003,7 @@ out: * 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, - struct affinity_context *ctx) +int __set_cpus_allowed_ptr(struct task_struct *p, struct affinity_context *ctx) { struct rq_flags rf; struct rq *rq; @@ -3318,9 +3122,6 @@ out_free_mask: free_cpumask_var(new_mask); } -static int -__sched_setaffinity(struct task_struct *p, struct affinity_context *ctx); - /* * Restore the affinity of a task @p which was previously restricted by a * call to force_compatible_cpus_allowed_ptr(). @@ -3700,12 +3501,6 @@ void sched_set_stop_task(int cpu, struct task_struct *stop) #else /* CONFIG_SMP */ -static inline int __set_cpus_allowed_ptr(struct task_struct *p, - struct affinity_context *ctx) -{ - return set_cpus_allowed_ptr(p, ctx->new_mask); -} - static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { } static inline bool rq_has_pinned_tasks(struct rq *rq) @@ -3713,11 +3508,6 @@ static inline bool rq_has_pinned_tasks(struct rq *rq) return false; } -static inline cpumask_t *alloc_user_cpus_ptr(int node) -{ - return NULL; -} - #endif /* !CONFIG_SMP */ static void @@ -3900,8 +3690,8 @@ void sched_ttwu_pending(void *arg) * it is possible for select_idle_siblings() to stack a number * of tasks on this CPU during that window. * - * It is ok to clear ttwu_pending when another task pending. - * We will receive IPI after local irq enabled and then enqueue it. + * It is OK to clear ttwu_pending when another task pending. + * We will receive IPI after local IRQ enabled and then enqueue it. * Since now nr_running > 0, idle_cpu() will always get correct result. */ WRITE_ONCE(rq->ttwu_pending, 0); @@ -5094,7 +4884,7 @@ __splice_balance_callbacks(struct rq *rq, bool split) return head; } -static inline struct balance_callback *splice_balance_callbacks(struct rq *rq) +struct balance_callback *splice_balance_callbacks(struct rq *rq) { return __splice_balance_callbacks(rq, true); } @@ -5104,7 +4894,7 @@ static void __balance_callbacks(struct rq *rq) do_balance_callbacks(rq, __splice_balance_callbacks(rq, false)); } -static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) +void balance_callbacks(struct rq *rq, struct balance_callback *head) { unsigned long flags; @@ -5121,15 +4911,6 @@ static inline void __balance_callbacks(struct rq *rq) { } -static inline struct balance_callback *splice_balance_callbacks(struct rq *rq) -{ - return NULL; -} - -static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) -{ -} - #endif static inline void @@ -5232,7 +5013,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, * * 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 + * 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) @@ -5555,9 +5336,9 @@ EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 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; + struct sched_entity *curr = p->se.cfs_rq->curr; #else - struct sched_entity *curr = (&task_rq(p)->cfs)->curr; + struct sched_entity *curr = task_rq(p)->cfs.curr; #endif prefetch(curr); prefetch(&curr->exec_start); @@ -5578,7 +5359,7 @@ unsigned long long task_sched_runtime(struct task_struct *p) /* * 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. + * 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 @@ -6856,7 +6637,7 @@ 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 + * 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. @@ -7051,9 +6832,9 @@ EXPORT_SYMBOL(dynamic_preempt_schedule_notrace); /* * 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. + * off of IRQ context. + * Note, that this is called and return with IRQs disabled. This will + * protect us against recursive calling from IRQ contexts. */ asmlinkage __visible void __sched preempt_schedule_irq(void) { @@ -7083,7 +6864,7 @@ int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flag } EXPORT_SYMBOL(default_wake_function); -static void __setscheduler_prio(struct task_struct *p, int prio) +void __setscheduler_prio(struct task_struct *p, int prio) { if (dl_prio(prio)) p->sched_class = &dl_sched_class; @@ -7123,21 +6904,6 @@ void rt_mutex_post_schedule(void) lockdep_assert(fetch_and_set(current->sched_rt_mutex, 0)); } -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 @@ -7187,7 +6953,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) goto out_unlock; /* - * Idle task boosting is a nono in general. There is one + * Idle task boosting is a no-no in general. There is one * exception, when PREEMPT_RT and NOHZ is active: * * The idle task calls get_next_timer_interrupt() and holds @@ -7266,1325 +7032,8 @@ out_unlock: 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; - struct rq *rq; - int old_prio; - - 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. - */ - CLASS(task_rq_lock, rq_guard)(p); - rq = rq_guard.rq; - - 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 won't 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); - return; - } - - 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); -} -EXPORT_SYMBOL(set_user_nice); - -/* - * is_nice_reduction - check if nice value is an actual reduction - * - * Similar to can_nice() but does not perform a capability check. - * - * @p: task - * @nice: nice value - */ -static bool is_nice_reduction(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)); -} - -/* - * 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) -{ - return is_nice_reduction(p, 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. - * - * sched policy return value kernel prio user prio/nice - * - * normal, batch, idle [0 ... 39] [100 ... 139] 0/[-20 ... 19] - * fifo, rr [-2 ... -100] [98 ... 0] [1 ... 99] - * deadline -101 -1 0 - */ -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 (rq->ttwu_pending) - 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; -} - -#ifdef CONFIG_SCHED_CORE -int sched_core_idle_cpu(int cpu) -{ - struct rq *rq = cpu_rq(cpu); - - if (sched_core_enabled(rq) && rq->curr == rq->idle) - return 1; - - return idle_cpu(cpu); -} - -#endif - -#ifdef CONFIG_SMP -/* - * This function computes an effective utilization for the given CPU, to be - * used for frequency selection given the linear relation: f = u * f_max. - * - * The scheduler tracks the following metrics: - * - * cpu_util_{cfs,rt,dl,irq}() - * cpu_bw_dl() - * - * Where the cfs,rt and dl util numbers are tracked with the same metric and - * synchronized windows and are thus directly comparable. - * - * The cfs,rt,dl utilization are the running times measured with rq->clock_task - * which excludes things like IRQ and steal-time. These latter are then accrued - * in the irq utilization. - * - * The DL bandwidth number otoh is not a measured metric but a value computed - * based on the task model parameters and gives the minimal utilization - * required to meet deadlines. - */ -unsigned long effective_cpu_util(int cpu, unsigned long util_cfs, - unsigned long *min, - unsigned long *max) -{ - unsigned long util, irq, scale; - struct rq *rq = cpu_rq(cpu); - - scale = arch_scale_cpu_capacity(cpu); - - /* - * Early check to see if IRQ/steal time saturates the CPU, can be - * because of inaccuracies in how we track these -- see - * update_irq_load_avg(). - */ - irq = cpu_util_irq(rq); - if (unlikely(irq >= scale)) { - if (min) - *min = scale; - if (max) - *max = scale; - return scale; - } - - if (min) { - /* - * The minimum utilization returns the highest level between: - * - the computed DL bandwidth needed with the IRQ pressure which - * steals time to the deadline task. - * - The minimum performance requirement for CFS and/or RT. - */ - *min = max(irq + cpu_bw_dl(rq), uclamp_rq_get(rq, UCLAMP_MIN)); - - /* - * When an RT task is runnable and uclamp is not used, we must - * ensure that the task will run at maximum compute capacity. - */ - if (!uclamp_is_used() && rt_rq_is_runnable(&rq->rt)) - *min = max(*min, scale); - } - - /* - * Because the time spend on RT/DL tasks is visible as 'lost' time to - * CFS tasks and we use the same metric to track the effective - * utilization (PELT windows are synchronized) we can directly add them - * to obtain the CPU's actual utilization. - */ - util = util_cfs + cpu_util_rt(rq); - util += cpu_util_dl(rq); - - /* - * The maximum hint is a soft bandwidth requirement, which can be lower - * than the actual utilization because of uclamp_max requirements. - */ - if (max) - *max = min(scale, uclamp_rq_get(rq, UCLAMP_MAX)); - - if (util >= scale) - return scale; - - /* - * There is still idle time; further improve the number by using the - * irq metric. Because IRQ/steal time is hidden from the task clock we - * need to scale the task numbers: - * - * max - irq - * U' = irq + --------- * U - * max - */ - util = scale_irq_capacity(util, irq, scale); - util += irq; - - return min(scale, util); -} - -unsigned long sched_cpu_util(int cpu) -{ - return effective_cpu_util(cpu, cpu_util_cfs(cpu), NULL, NULL); -} -#endif /* CONFIG_SMP */ - -/** - * 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; -} - -static struct task_struct *find_get_task(pid_t pid) -{ - struct task_struct *p; - guard(rcu)(); - - p = find_process_by_pid(pid); - if (likely(p)) - get_task_struct(p); - - return p; -} - -DEFINE_CLASS(find_get_task, struct task_struct *, if (_T) put_task_struct(_T), - find_get_task(pid), pid_t pid) - -/* - * 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); -} - -/* - * 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; - guard(rcu)(); - - pcred = __task_cred(p); - return (uid_eq(cred->euid, pcred->euid) || - uid_eq(cred->euid, pcred->uid)); -} - -/* - * Allow unprivileged RT tasks to decrease priority. - * Only issue a capable test if needed and only once to avoid an audit - * event on permitted non-privileged operations: - */ -static int user_check_sched_setscheduler(struct task_struct *p, - const struct sched_attr *attr, - int policy, int reset_on_fork) -{ - if (fair_policy(policy)) { - if (attr->sched_nice < task_nice(p) && - !is_nice_reduction(p, attr->sched_nice)) - goto req_priv; - } - - 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) - goto req_priv; - - /* Can't increase priority: */ - if (attr->sched_priority > p->rt_priority && - attr->sched_priority > rlim_rtprio) - goto req_priv; - } - - /* - * 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)) - goto req_priv; - - /* - * 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 (!is_nice_reduction(p, task_nice(p))) - goto req_priv; - } - - /* Can't change other user's priorities: */ - if (!check_same_owner(p)) - goto req_priv; - - /* Normal users shall not reset the sched_reset_on_fork flag: */ - if (p->sched_reset_on_fork && !reset_on_fork) - goto req_priv; - - return 0; - -req_priv: - if (!capable(CAP_SYS_NICE)) - return -EPERM; - - return 0; -} - -static int __sched_setscheduler(struct task_struct *p, - const struct sched_attr *attr, - bool user, bool pi) -{ - int oldpolicy = -1, policy = attr->sched_policy; - int retval, oldprio, newprio, queued, running; - const struct sched_class *prev_class; - struct balance_callback *head; - struct rq_flags rf; - int reset_on_fork; - int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; - struct rq *rq; - bool cpuset_locked = false; - - /* 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_RT_PRIO-1, valid priority for SCHED_NORMAL, - * SCHED_BATCH and SCHED_IDLE is 0. - */ - if (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; - - if (user) { - retval = user_check_sched_setscheduler(p, attr, policy, reset_on_fork); - if (retval) - return retval; - - 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; - } - - /* - * SCHED_DEADLINE bandwidth accounting relies on stable cpusets - * information. - */ - if (dl_policy(policy) || dl_policy(p->policy)) { - cpuset_locked = true; - cpuset_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 (cpuset_locked) - cpuset_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; - - newprio = __normal_prio(policy, attr->sched_priority, attr->sched_nice); - if (pi) { - /* - * Take priority boosted tasks into account. If the new - * effective priority is unchanged, we just store the new - * normal parameters and do not touch the scheduler class and - * the runqueue. This will be done when the task deboost - * itself. - */ - newprio = rt_effective_prio(p, newprio); - if (newprio == 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; - - if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) { - __setscheduler_params(p, attr); - __setscheduler_prio(p, newprio); - } - __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(); - head = splice_balance_callbacks(rq); - task_rq_unlock(rq, p, &rf); - - if (pi) { - if (cpuset_locked) - cpuset_unlock(); - rt_mutex_adjust_pi(p); - } - - /* Run balance callbacks after we've adjusted the PI chain: */ - balance_callbacks(rq, head); - preempt_enable(); - - return 0; - -unlock: - task_rq_unlock(rq, p, &rf); - if (cpuset_locked) - cpuset_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. - * - * Use sched_set_fifo(), read its comment. - * - * 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); -} - -int sched_setattr(struct task_struct *p, const struct sched_attr *attr) -{ - return __sched_setscheduler(p, attr, true, true); -} - -int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr) -{ - return __sched_setscheduler(p, attr, false, true); -} -EXPORT_SYMBOL_GPL(sched_setattr_nocheck); - -/** - * 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); -} - -/* - * SCHED_FIFO is a broken scheduler model; that is, it is fundamentally - * incapable of resource management, which is the one thing an OS really should - * be doing. - * - * This is of course the reason it is limited to privileged users only. - * - * Worse still; it is fundamentally impossible to compose static priority - * workloads. You cannot take two correctly working static prio workloads - * and smash them together and still expect them to work. - * - * For this reason 'all' FIFO tasks the kernel creates are basically at: - * - * MAX_RT_PRIO / 2 - * - * The administrator _MUST_ configure the system, the kernel simply doesn't - * know enough information to make a sensible choice. - */ -void sched_set_fifo(struct task_struct *p) -{ - struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 }; - WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0); -} -EXPORT_SYMBOL_GPL(sched_set_fifo); - -/* - * For when you don't much care about FIFO, but want to be above SCHED_NORMAL. - */ -void sched_set_fifo_low(struct task_struct *p) -{ - struct sched_param sp = { .sched_priority = 1 }; - WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0); -} -EXPORT_SYMBOL_GPL(sched_set_fifo_low); - -void sched_set_normal(struct task_struct *p, int nice) -{ - struct sched_attr attr = { - .sched_policy = SCHED_NORMAL, - .sched_nice = nice, - }; - WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0); -} -EXPORT_SYMBOL_GPL(sched_set_normal); - -static int -do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) -{ - struct sched_param lparam; - - if (!param || pid < 0) - return -EINVAL; - if (copy_from_user(&lparam, param, sizeof(struct sched_param))) - return -EFAULT; - - CLASS(find_get_task, p)(pid); - if (!p) - return -ESRCH; - - return sched_setscheduler(p, policy, &lparam); -} - -/* - * 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; -} - -static void get_params(struct task_struct *p, struct sched_attr *attr) -{ - if (task_has_dl_policy(p)) - __getparam_dl(p, attr); - else if (task_has_rt_policy(p)) - attr->sched_priority = p->rt_priority; - else - attr->sched_nice = task_nice(p); -} - -/** - * 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; - 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; - - CLASS(find_get_task, p)(pid); - if (!p) - return -ESRCH; - - if (attr.sched_flags & SCHED_FLAG_KEEP_PARAMS) - get_params(p, &attr); - - return sched_setattr(p, &attr); -} - -/** - * 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; - - guard(rcu)(); - p = find_process_by_pid(pid); - if (!p) - return -ESRCH; - - retval = security_task_getscheduler(p); - if (!retval) { - retval = p->policy; - if (p->sched_reset_on_fork) - retval |= SCHED_RESET_ON_FORK; - } - 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; - - scoped_guard (rcu) { - p = find_process_by_pid(pid); - if (!p) - return -ESRCH; - - retval = security_task_getscheduler(p); - if (retval) - return retval; - - if (task_has_rt_policy(p)) - lp.sched_priority = p->rt_priority; - } - - /* - * This one might sleep, we cannot do it with a spinlock held ... - */ - return copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; -} - -/* - * 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; - - scoped_guard (rcu) { - p = find_process_by_pid(pid); - if (!p) - return -ESRCH; - - retval = security_task_getscheduler(p); - if (retval) - return retval; - - kattr.sched_policy = p->policy; - if (p->sched_reset_on_fork) - kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; - get_params(p, &kattr); - kattr.sched_flags &= SCHED_FLAG_ALL; - -#ifdef CONFIG_UCLAMP_TASK - /* - * This could race with another potential updater, but this is fine - * because it'll correctly read the old or the new value. We don't need - * to guarantee who wins the race as long as it doesn't return garbage. - */ - kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value; - kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value; -#endif - } - - return sched_attr_copy_to_user(uattr, &kattr, usize); -} - -#ifdef CONFIG_SMP -int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask) -{ - /* - * If the task isn't a deadline task or admission control is - * disabled then we don't care about affinity changes. - */ - if (!task_has_dl_policy(p) || !dl_bandwidth_enabled()) - return 0; - - /* - * 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. - */ - guard(rcu)(); - if (!cpumask_subset(task_rq(p)->rd->span, mask)) - return -EBUSY; - - return 0; -} #endif -static int -__sched_setaffinity(struct task_struct *p, struct affinity_context *ctx) -{ - int retval; - cpumask_var_t cpus_allowed, new_mask; - - if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) - return -ENOMEM; - - if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { - retval = -ENOMEM; - goto out_free_cpus_allowed; - } - - cpuset_cpus_allowed(p, cpus_allowed); - cpumask_and(new_mask, ctx->new_mask, cpus_allowed); - - ctx->new_mask = new_mask; - ctx->flags |= SCA_CHECK; - - retval = dl_task_check_affinity(p, new_mask); - if (retval) - goto out_free_new_mask; - - retval = __set_cpus_allowed_ptr(p, ctx); - if (retval) - goto out_free_new_mask; - - 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 cpumask to the cpuset's cpus_allowed. - */ - cpumask_copy(new_mask, cpus_allowed); - - /* - * If SCA_USER is set, a 2nd call to __set_cpus_allowed_ptr() - * will restore the previous user_cpus_ptr value. - * - * In the unlikely event a previous user_cpus_ptr exists, - * we need to further restrict the mask to what is allowed - * by that old user_cpus_ptr. - */ - if (unlikely((ctx->flags & SCA_USER) && ctx->user_mask)) { - bool empty = !cpumask_and(new_mask, new_mask, - ctx->user_mask); - - if (WARN_ON_ONCE(empty)) - cpumask_copy(new_mask, cpus_allowed); - } - __set_cpus_allowed_ptr(p, ctx); - retval = -EINVAL; - } - -out_free_new_mask: - free_cpumask_var(new_mask); -out_free_cpus_allowed: - free_cpumask_var(cpus_allowed); - return retval; -} - -long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) -{ - struct affinity_context ac; - struct cpumask *user_mask; - int retval; - - CLASS(find_get_task, p)(pid); - if (!p) - return -ESRCH; - - if (p->flags & PF_NO_SETAFFINITY) - return -EINVAL; - - if (!check_same_owner(p)) { - guard(rcu)(); - if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) - return -EPERM; - } - - retval = security_task_setscheduler(p); - if (retval) - return retval; - - /* - * With non-SMP configs, user_cpus_ptr/user_mask isn't used and - * alloc_user_cpus_ptr() returns NULL. - */ - user_mask = alloc_user_cpus_ptr(NUMA_NO_NODE); - if (user_mask) { - cpumask_copy(user_mask, in_mask); - } else if (IS_ENABLED(CONFIG_SMP)) { - return -ENOMEM; - } - - ac = (struct affinity_context){ - .new_mask = in_mask, - .user_mask = user_mask, - .flags = SCA_USER, - }; - - retval = __sched_setaffinity(p, &ac); - kfree(ac.user_mask); - - 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; - int retval; - - guard(rcu)(); - p = find_process_by_pid(pid); - if (!p) - return -ESRCH; - - retval = security_task_getscheduler(p); - if (retval) - return retval; - - guard(raw_spinlock_irqsave)(&p->pi_lock); - cpumask_and(mask, &p->cpus_mask, cpu_active_mask); - - return 0; -} - -/** - * 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 (!zalloc_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, cpumask_bits(mask), retlen)) - ret = -EFAULT; - else - ret = retlen; - } - free_cpumask_var(mask); - - return ret; -} - -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); - - preempt_disable(); - rq_unlock_irq(rq, &rf); - sched_preempt_enable_no_resched(); - - schedule(); -} - -/** - * 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. - */ -SYSCALL_DEFINE0(sched_yield) -{ - do_sched_yield(); - return 0; -} - #if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) int __sched __cond_resched(void) { @@ -8907,105 +7356,11 @@ PREEMPT_MODEL_ACCESSOR(none); PREEMPT_MODEL_ACCESSOR(voluntary); PREEMPT_MODEL_ACCESSOR(full); -#else /* !CONFIG_PREEMPT_DYNAMIC */ +#else /* !CONFIG_PREEMPT_DYNAMIC: */ static inline void preempt_dynamic_init(void) { } -#endif /* #ifdef CONFIG_PREEMPT_DYNAMIC */ - -/** - * 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, it's 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; - int yielded = 0; - - scoped_guard (irqsave) { - 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) - return -ESRCH; - - guard(double_rq_lock)(rq, p_rq); - if (task_rq(p) != p_rq) - goto again; - - if (!curr->sched_class->yield_to_task) - return 0; - - if (curr->sched_class != p->sched_class) - return 0; - - if (task_on_cpu(p_rq, p) || !task_is_running(p)) - return 0; - - yielded = curr->sched_class->yield_to_task(rq, p); - 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); - } - } - - if (yielded) - schedule(); - - return yielded; -} -EXPORT_SYMBOL_GPL(yield_to); +#endif /* CONFIG_PREEMPT_DYNAMIC */ int io_schedule_prepare(void) { @@ -9048,123 +7403,6 @@ void __sched io_schedule(void) } 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_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) -{ - unsigned int time_slice = 0; - int retval; - - if (pid < 0) - return -EINVAL; - - scoped_guard (rcu) { - struct task_struct *p = find_process_by_pid(pid); - if (!p) - return -ESRCH; - - retval = security_task_getscheduler(p); - if (retval) - return retval; - - scoped_guard (task_rq_lock, p) { - struct rq *rq = scope.rq; - if (p->sched_class->get_rr_interval) - time_slice = p->sched_class->get_rr_interval(rq, p); - } - } - - jiffies_to_timespec64(time_slice, t); - return 0; -} - -/** - * 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; @@ -9732,7 +7970,7 @@ int sched_cpu_deactivate(unsigned int cpu) * Specifically, we rely on ttwu to no longer target this CPU, see * ttwu_queue_cond() and is_cpu_allowed(). * - * Do sync before park smpboot threads to take care the rcu boost case. + * Do sync before park smpboot threads to take care the RCU boost case. */ synchronize_rcu(); @@ -9807,7 +8045,7 @@ int sched_cpu_wait_empty(unsigned int cpu) * Since this CPU is going 'away' for a while, fold any nr_active delta we * might have. Called from the CPU stopper task after ensuring that the * stopper is the last running task on the CPU, so nr_active count is - * stable. We need to take the teardown thread which is calling this into + * stable. We need to take the tear-down thread which is calling this into * account, so we hand in adjust = 1 to the load calculation. * * Also see the comment "Global load-average calculations". @@ -10001,7 +8239,7 @@ void __init sched_init(void) /* * How much CPU bandwidth does root_task_group get? * - * In case of task-groups formed thr' the cgroup filesystem, it + * In case of task-groups formed through 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, @@ -10303,7 +8541,7 @@ void normalize_rt_tasks(void) #if defined(CONFIG_KGDB_KDB) /* - * These functions are only useful for kdb. + * These functions are only useful for KDB. * * They can only be called when the whole system has been * stopped - every CPU needs to be quiescent, and no scheduling @@ -10411,7 +8649,7 @@ void sched_online_group(struct task_group *tg, struct task_group *parent) online_fair_sched_group(tg); } -/* rcu callback to free various structures associated with a task group */ +/* RCU callback to free various structures associated with a task group */ static void sched_unregister_group_rcu(struct rcu_head *rhp) { /* Now it should be safe to free those cfs_rqs: */ @@ -11529,10 +9767,10 @@ const int sched_prio_to_weight[40] = { }; /* - * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. + * Inverse (2^32/x) values of the sched_prio_to_weight[] array, pre-calculated. * * In cases where the weight does not change often, we can use the - * precalculated inverse to speed up arithmetics by turning divisions + * pre-calculated inverse to speed up arithmetics by turning divisions * into multiplications: */ const u32 sched_prio_to_wmult[40] = { @@ -11788,16 +10026,16 @@ void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t) /* * Move the src cid if the dst cid is unset. This keeps id * allocation closest to 0 in cases where few threads migrate around - * many cpus. + * many CPUs. * * If destination cid is already set, we may have to just clear * the src cid to ensure compactness in frequent migrations * scenarios. * * It is not useful to clear the src cid when the number of threads is - * greater or equal to the number of allowed cpus, because user-space + * greater or equal to the number of allowed CPUs, because user-space * can expect that the number of allowed cids can reach the number of - * allowed cpus. + * allowed CPUs. */ dst_pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu_of(dst_rq)); dst_cid = READ_ONCE(dst_pcpu_cid->cid); |