[PATCH openEuler-26.09 099/399] sched/syscalls: Split out kernel/sched/syscalls.c from kernel/sched/core.c

From: Ingo Molnar <mingo@kernel.org> mainline inclusion from mainline-v6.11-rc1 commit 04746ed80bcf3130951ed4d5c1bc5b0bcabdde22 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IDC9YK Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi... -------------------------------- core.c has become rather large, move most scheduler syscall related functionality into a separate file, syscalls.c. This is about ~15% of core.c's raw linecount. Move the alloc_user_cpus_ptr(), __rt_effective_prio(), rt_effective_prio(), uclamp_none(), uclamp_se_set() and uclamp_bucket_id() inlines to kernel/sched/sched.h. Internally export the __sched_setscheduler(), __sched_setaffinity(), __setscheduler_prio(), set_load_weight(), enqueue_task(), dequeue_task(), check_class_changed(), splice_balance_callbacks() and balance_callbacks() methods to better facilitate this. Move the new file's build to sched_policy.c, because it fits there semantically, but also because it's the smallest of the 4 build units under an allmodconfig build: -rw-rw-r-- 1 mingo mingo 7.3M May 27 12:35 kernel/sched/core.i -rw-rw-r-- 1 mingo mingo 6.4M May 27 12:36 kernel/sched/build_utility.i -rw-rw-r-- 1 mingo mingo 6.3M May 27 12:36 kernel/sched/fair.i -rw-rw-r-- 1 mingo mingo 5.8M May 27 12:36 kernel/sched/build_policy.i This better balances build time for scheduler subsystem rebuilds. I build-tested this new file as a standalone syscalls.o file for a bit, to make sure all the encapsulations & abstractions are robust. Also update/add my copyright notices to these files. Build time measurements: # -Before/+After: kepler:~/tip> perf stat -e 'cycles,instructions,duration_time' --sync --repeat 5 --pre 'rm -f kernel/sched/*.o' m kernel/sched/built-in.a >/dev/null Performance counter stats for 'm kernel/sched/built-in.a' (5 runs): - 71,938,508,607 cycles ( +- 0.17% ) + 71,992,916,493 cycles ( +- 0.22% ) - 106,214,780,964 instructions # 1.48 insn per cycle ( +- 0.01% ) + 105,450,231,154 instructions # 1.46 insn per cycle ( +- 0.01% ) - 5,878,232,620 ns duration_time ( +- 0.38% ) + 5,290,085,069 ns duration_time ( +- 0.21% ) - 5.8782 +- 0.0221 seconds time elapsed ( +- 0.38% ) + 5.2901 +- 0.0111 seconds time elapsed ( +- 0.21% ) Build time improvement of -11.1% (duration_time) is expected: the parallel build time of the scheduler subsystem is determined by the largest, slowest to build object file, which is kernel/sched/core.o. By moving ~15% of its complexity into another build unit, we reduced build time by -11%. Measured cycles spent on building is within its ~0.2% stddev noise envelope. The -0.7% reduction in instructions spent on building the scheduler is statistically reliable and somewhat surprising - I can only speculate: maybe compilers aren't that efficient at building & optimizing 10+ KLOC files (core.c), and it's an overall win to balance the linecount a bit. Anyway, this might be a data point that suggests that reducing the linecount of our largest files will improve not just code readability and maintainability, but might also improve build times a bit. Code generation got a bit worse, by 0.5kb text on an x86 defconfig build: # -Before/+After: kepler:~/tip> size vmlinux text data bss dec hex filename -26475475 10439178 1740804 38655457 24dd5e1 vmlinux +26476003 10439178 1740804 38655985 24dd7f1 vmlinux kepler:~/tip> size kernel/sched/built-in.a text data bss dec hex filename - 76056 30025 489 106570 1a04a kernel/sched/core.o (ex kernel/sched/built-in.a) + 63452 29453 489 93394 16cd2 kernel/sched/core.o (ex kernel/sched/built-in.a) 44299 2181 104 46584 b5f8 kernel/sched/fair.o (ex kernel/sched/built-in.a) - 42764 3424 120 46308 b4e4 kernel/sched/build_policy.o (ex kernel/sched/built-in.a) + 55651 4044 120 59815 e9a7 kernel/sched/build_policy.o (ex kernel/sched/built-in.a) 44866 12655 2192 59713 e941 kernel/sched/build_utility.o (ex kernel/sched/built-in.a) 44866 12655 2192 59713 e941 kernel/sched/build_utility.o (ex kernel/sched/built-in.a) This is primarily due to the extra functions exported, and the size gets exaggerated somewhat by __pfx CFI function padding: ffffffff810cc710 <__pfx_enqueue_task>: ffffffff810cc710: 90 nop ffffffff810cc711: 90 nop ffffffff810cc712: 90 nop ffffffff810cc713: 90 nop ffffffff810cc714: 90 nop ffffffff810cc715: 90 nop ffffffff810cc716: 90 nop ffffffff810cc717: 90 nop ffffffff810cc718: 90 nop ffffffff810cc719: 90 nop ffffffff810cc71a: 90 nop ffffffff810cc71b: 90 nop ffffffff810cc71c: 90 nop ffffffff810cc71d: 90 nop ffffffff810cc71e: 90 nop ffffffff810cc71f: 90 nop AFAICS the cost is primarily not to core.o and fair.o though (which contain most performance sensitive scheduler functions), only to syscalls.o that get called with much lower frequency - so I think this is an acceptable trade-off for better code separation. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Link: https://lore.kernel.org/r/20240407084319.1462211-2-mingo@kernel.org Conflicts: kernel/sched/core.c kernel/sched/sched.h kernel/sched/build_policy.c [The code move from core.c to syscalls.c, this version has additional patches more than the mainline one, 1621f4654db7 ("sched: Introduce qos scheduler for co-location"), so move it together to the new file syscalls.c. Fix compile error for the code move from sched/core.c to sched/syscalls.c in 04746ed80bcf ("sched/syscalls: Split out kernel/sched/syscalls.c from kernel/sched/core.c"). As for other conflicts, only pick the part modified by this mainline commit, and ignore the conflict part caused by higher version.] Signed-off-by: Zicheng Qu <quzicheng@huawei.com> --- kernel/sched/build_policy.c | 1 + kernel/sched/core.c | 1973 ++--------------------------------- kernel/sched/sched.h | 134 ++- kernel/sched/syscalls.c | 1693 ++++++++++++++++++++++++++++++ 4 files changed, 1923 insertions(+), 1878 deletions(-) create mode 100644 kernel/sched/syscalls.c diff --git a/kernel/sched/build_policy.c b/kernel/sched/build_policy.c index 6aff6482b1e7..e954328cc093 100644 --- a/kernel/sched/build_policy.c +++ b/kernel/sched/build_policy.c @@ -55,3 +55,4 @@ #ifdef CONFIG_SCHED_SOFT_DOMAIN #include "soft_domain.c" #endif +#include "syscalls.c" diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e79db8baa135..1bf2b2ec53f2 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> @@ -1315,7 +1316,7 @@ 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 lw; @@ -1372,7 +1373,7 @@ 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]; @@ -1397,32 +1398,6 @@ 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) @@ -1888,107 +1863,6 @@ static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, #endif #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; @@ -2056,13 +1930,6 @@ 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) { } @@ -2092,7 +1959,7 @@ 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); @@ -2109,7 +1976,7 @@ 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); @@ -2145,52 +2012,6 @@ 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. @@ -2209,9 +2030,9 @@ 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) @@ -2383,9 +2204,6 @@ 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 = { @@ -2819,16 +2637,6 @@ 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) { @@ -3197,8 +3005,7 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p, * 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; @@ -3317,9 +3124,6 @@ void force_compatible_cpus_allowed_ptr(struct task_struct *p) 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(). @@ -3699,12 +3503,6 @@ 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) @@ -3712,11 +3510,6 @@ 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 @@ -5141,7 +4934,7 @@ __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); } @@ -5151,7 +4944,7 @@ 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; @@ -5168,15 +4961,6 @@ 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 @@ -7095,7 +6879,7 @@ 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; @@ -7109,21 +6893,6 @@ static void __setscheduler_prio(struct task_struct *p, int prio) #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 @@ -7252,1454 +7021,117 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) 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) +#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) +int __sched __cond_resched(void) { - 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; + if (should_resched(0) && !irqs_disabled()) { + preempt_schedule_common(); + return 1; } - - 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: + * In preemptible kernels, ->rcu_read_lock_nesting tells the tick + * whether the current CPU is in an RCU read-side critical section, + * so the tick can report quiescent states even for CPUs looping + * in kernel context. In contrast, in non-preemptible kernels, + * RCU readers leave no in-memory hints, which means that CPU-bound + * processes executing in kernel context might never report an + * RCU quiescent state. Therefore, the following code causes + * cond_resched() to report a quiescent state, but only when RCU + * is in urgent need of one. */ - p->sched_class->prio_changed(rq, p, old_prio); +#ifndef CONFIG_PREEMPT_RCU + rcu_all_qs(); +#endif + return 0; } -EXPORT_SYMBOL(set_user_nice); +EXPORT_SYMBOL(__cond_resched); +#endif -/* - * 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); +#ifdef CONFIG_PREEMPT_DYNAMIC +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) +#define cond_resched_dynamic_enabled __cond_resched +#define cond_resched_dynamic_disabled ((void *)&__static_call_return0) +DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(cond_resched); - return (nice_rlim <= task_rlimit(p, RLIMIT_NICE)); +#define might_resched_dynamic_enabled __cond_resched +#define might_resched_dynamic_disabled ((void *)&__static_call_return0) +DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(might_resched); +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched); +int __sched dynamic_cond_resched(void) +{ + klp_sched_try_switch(); + if (!static_branch_unlikely(&sk_dynamic_cond_resched)) + return 0; + return __cond_resched(); } +EXPORT_SYMBOL(dynamic_cond_resched); -/* - * 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) +static DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched); +int __sched dynamic_might_resched(void) { - return is_nice_reduction(p, nice) || capable(CAP_SYS_NICE); + if (!static_branch_unlikely(&sk_dynamic_might_resched)) + return 0; + return __cond_resched(); } - -#ifdef __ARCH_WANT_SYS_NICE +EXPORT_SYMBOL(dynamic_might_resched); +#endif +#endif /* - * sys_nice - change the priority of the current process. - * @increment: priority increment + * __cond_resched_lock() - if a reschedule is pending, drop the given lock, + * call schedule, and on return reacquire the lock. * - * sys_setpriority is a more generic, but much slower function that - * does similar things. + * 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). */ -SYSCALL_DEFINE1(nice, int, increment) +int __cond_resched_lock(spinlock_t *lock) { - 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; + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; - retval = security_task_setnice(current, nice); - if (retval) - return retval; + lockdep_assert_held(lock); - set_user_nice(current, nice); - return 0; + if (spin_needbreak(lock) || resched) { + spin_unlock(lock); + if (!_cond_resched()) + cpu_relax(); + ret = 1; + spin_lock(lock); + } + return ret; } +EXPORT_SYMBOL(__cond_resched_lock); -#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) +int __cond_resched_rwlock_read(rwlock_t *lock) { - return p->prio - MAX_RT_PRIO; + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held_read(lock); + + if (rwlock_needbreak(lock) || resched) { + read_unlock(lock); + if (!_cond_resched()) + cpu_relax(); + ret = 1; + read_lock(lock); + } + return ret; } +EXPORT_SYMBOL(__cond_resched_rwlock_read); -/** - * 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) +int __cond_resched_rwlock_write(rwlock_t *lock) { - struct rq *rq = cpu_rq(cpu); + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; - 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); - - /* rt-policy tasks do not have a timerslack */ - if (task_is_realtime(p)) { - p->timer_slack_ns = 0; - } else if (p->timer_slack_ns == 0) { - /* when switching back to non-rt policy, restore timerslack */ - p->timer_slack_ns = p->default_timer_slack_ns; - } - - /* - * __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: - -#ifdef CONFIG_QOS_SCHED - /* - * If the scheduling policy of an offline task is set to a policy - * other than SCHED_IDLE, the online task preemption and cpu resource - * isolation will be invalid, so return -EINVAL in this case. - */ - if (unlikely(is_offline_level(task_group(p)->qos_level) && !idle_policy(policy))) { - retval = -EINVAL; - goto unlock; - } -#endif - - 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 (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) -{ - if (should_resched(0) && !irqs_disabled()) { - preempt_schedule_common(); - return 1; - } - /* - * In preemptible kernels, ->rcu_read_lock_nesting tells the tick - * whether the current CPU is in an RCU read-side critical section, - * so the tick can report quiescent states even for CPUs looping - * in kernel context. In contrast, in non-preemptible kernels, - * RCU readers leave no in-memory hints, which means that CPU-bound - * processes executing in kernel context might never report an - * RCU quiescent state. Therefore, the following code causes - * cond_resched() to report a quiescent state, but only when RCU - * is in urgent need of one. - */ -#ifndef CONFIG_PREEMPT_RCU - rcu_all_qs(); -#endif - return 0; -} -EXPORT_SYMBOL(__cond_resched); -#endif - -#ifdef CONFIG_PREEMPT_DYNAMIC -#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) -#define cond_resched_dynamic_enabled __cond_resched -#define cond_resched_dynamic_disabled ((void *)&__static_call_return0) -DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched); -EXPORT_STATIC_CALL_TRAMP(cond_resched); - -#define might_resched_dynamic_enabled __cond_resched -#define might_resched_dynamic_disabled ((void *)&__static_call_return0) -DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched); -EXPORT_STATIC_CALL_TRAMP(might_resched); -#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) -static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched); -int __sched dynamic_cond_resched(void) -{ - klp_sched_try_switch(); - if (!static_branch_unlikely(&sk_dynamic_cond_resched)) - return 0; - return __cond_resched(); -} -EXPORT_SYMBOL(dynamic_cond_resched); - -static DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched); -int __sched dynamic_might_resched(void) -{ - if (!static_branch_unlikely(&sk_dynamic_might_resched)) - return 0; - return __cond_resched(); -} -EXPORT_SYMBOL(dynamic_might_resched); -#endif -#endif - -/* - * __cond_resched_lock() - if a reschedule is pending, drop the given lock, - * call schedule, and on return reacquire the lock. - * - * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level - * operations here to prevent schedule() from being called twice (once via - * spin_unlock(), once by hand). - */ -int __cond_resched_lock(spinlock_t *lock) -{ - int resched = should_resched(PREEMPT_LOCK_OFFSET); - int ret = 0; - - lockdep_assert_held(lock); - - if (spin_needbreak(lock) || resched) { - spin_unlock(lock); - if (!_cond_resched()) - cpu_relax(); - ret = 1; - spin_lock(lock); - } - return ret; -} -EXPORT_SYMBOL(__cond_resched_lock); - -int __cond_resched_rwlock_read(rwlock_t *lock) -{ - int resched = should_resched(PREEMPT_LOCK_OFFSET); - int ret = 0; - - lockdep_assert_held_read(lock); - - if (rwlock_needbreak(lock) || resched) { - read_unlock(lock); - if (!_cond_resched()) - cpu_relax(); - ret = 1; - read_lock(lock); - } - return ret; -} -EXPORT_SYMBOL(__cond_resched_rwlock_read); - -int __cond_resched_rwlock_write(rwlock_t *lock) -{ - int resched = should_resched(PREEMPT_LOCK_OFFSET); - int ret = 0; - - lockdep_assert_held_write(lock); + lockdep_assert_held_write(lock); if (rwlock_needbreak(lock) || resched) { write_unlock(lock); @@ -8919,100 +7351,6 @@ 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 (raw_spinlock_irqsave, &p->pi_lock) { - 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); - int io_schedule_prepare(void) { int old_iowait = current->in_iowait; @@ -9054,123 +7392,6 @@ 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; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 34c421fa3783..d133efd5f3e5 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2583,8 +2583,19 @@ extern void update_group_capacity(struct sched_domain *sd, int cpu); extern void trigger_load_balance(struct rq *rq); +extern int __set_cpus_allowed_ptr(struct task_struct *p, struct affinity_context *ctx); extern void set_cpus_allowed_common(struct task_struct *p, struct affinity_context *ctx); +static inline cpumask_t *alloc_user_cpus_ptr(int node) +{ + /* + * See do_set_cpus_allowed() above for the rcu_head usage. + */ + int size = max_t(int, cpumask_size(), sizeof(struct rcu_head)); + + return kmalloc_node(size, GFP_KERNEL, node); +} + static inline struct task_struct *get_push_task(struct rq *rq) { struct task_struct *p = rq->curr; @@ -2606,7 +2617,20 @@ static inline struct task_struct *get_push_task(struct rq *rq) extern int push_cpu_stop(void *arg); -#endif +#else /* !CONFIG_SMP: */ + +static inline int __set_cpus_allowed_ptr(struct task_struct *p, + struct affinity_context *ctx) +{ + return set_cpus_allowed_ptr(p, ctx->new_mask); +} + +static inline cpumask_t *alloc_user_cpus_ptr(int node) +{ + return NULL; +} + +#endif /* !CONFIG_SMP */ #ifdef CONFIG_CPU_IDLE static inline void idle_set_state(struct rq *rq, @@ -3337,6 +3361,36 @@ static inline bool uclamp_is_used(void) { return static_branch_likely(&sched_uclamp_used); } + +#define for_each_clamp_id(clamp_id) \ + for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++) + +extern unsigned int sysctl_sched_uclamp_util_min_rt_default; + + +static inline unsigned int uclamp_none(enum uclamp_id clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + return SCHED_CAPACITY_SCALE; +} + +/* Integer rounded range for each bucket */ +#define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS) + +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 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; +} + #else /* CONFIG_UCLAMP_TASK */ static inline unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id) @@ -3379,6 +3433,7 @@ static inline bool uclamp_rq_is_idle(struct rq *rq) { return false; } + #endif /* CONFIG_UCLAMP_TASK */ #ifdef CONFIG_HAVE_SCHED_AVG_IRQ @@ -3766,7 +3821,82 @@ extern int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se); #ifdef CONFIG_BPF_SCHED bool bpf_sched_is_cpu_allowed(struct task_struct *p, int cpu); -#endif +#endif /* CONFIG_BPF_SCHED */ +#ifdef CONFIG_RT_MUTEXES +static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) +{ + if (pi_task) + prio = min(prio, pi_task->prio); + + return prio; +} + +static inline int rt_effective_prio(struct task_struct *p, int prio) +{ + struct task_struct *pi_task = rt_mutex_get_top_task(p); + + return __rt_effective_prio(pi_task, prio); +} +#else +static inline int rt_effective_prio(struct task_struct *p, int prio) +{ + return prio; +} +#endif /* CONFIG_RT_MUTEXES */ + +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)); +} + +extern int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user, bool pi); +extern int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx); +extern void __setscheduler_prio(struct task_struct *p, int prio); +extern void __setscheduler_params(struct task_struct *p, const struct sched_attr *attr); +extern void set_load_weight(struct task_struct *p, bool update_load); +extern void enqueue_task(struct rq *rq, struct task_struct *p, int flags); +extern void dequeue_task(struct rq *rq, struct task_struct *p, int flags); + +extern void check_class_changed(struct rq *rq, struct task_struct *p, + const struct sched_class *prev_class, + int oldprio); + +#ifdef CONFIG_SMP +extern struct balance_callback *splice_balance_callbacks(struct rq *rq); +extern void balance_callbacks(struct rq *rq, struct balance_callback *head); +#else + +static inline struct balance_callback *splice_balance_callbacks(struct rq *rq) +{ + return NULL; +} + +static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) +{ +} + +#endif /* CONFIG_SMP */ #ifdef CONFIG_SCHED_SOFT_DOMAIN void build_soft_domain(void); diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c new file mode 100644 index 000000000000..5f4eaecb90cd --- /dev/null +++ b/kernel/sched/syscalls.c @@ -0,0 +1,1693 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kernel/sched/syscalls.c + * + * Core kernel scheduler syscalls related code + * + * Copyright (C) 1991-2002 Linus Torvalds + * Copyright (C) 1998-2024 Ingo Molnar, Red Hat + */ +#include <linux/sched.h> +#include <linux/cpuset.h> +#include <linux/sched/debug.h> + +#include <uapi/linux/sched/types.h> + +#include "sched.h" +#include "autogroup.h" + +/* + * 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; +} + +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 + +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); + + /* rt-policy tasks do not have a timerslack */ + if (task_is_realtime(p)) { + p->timer_slack_ns = 0; + } else if (p->timer_slack_ns == 0) { + /* when switching back to non-rt policy, restore timerslack */ + p->timer_slack_ns = p->default_timer_slack_ns; + } + + /* + * __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)); +} + +#ifdef CONFIG_UCLAMP_TASK + +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); + } +} + +#else /* !CONFIG_UCLAMP_TASK: */ + +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) { } +#endif + +/* + * 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; +} + +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: + +#ifdef CONFIG_QOS_SCHED + /* + * If the scheduling policy of an offline task is set to a policy + * other than SCHED_IDLE, the online task preemption and cpu resource + * isolation will be invalid, so return -EINVAL in this case. + */ + if (unlikely(is_offline_level(task_group(p)->qos_level) && !idle_policy(policy))) { + retval = -EINVAL; + goto unlock; + } +#endif + + 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 /* CONFIG_SMP */ + +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 (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; +} + +/** + * 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 (raw_spinlock_irqsave, &p->pi_lock) { + 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); + +/** + * 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 -- 2.34.1