diff options
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 76 | ||||
| -rw-r--r-- | kernel/sched/deadline.c | 4 | ||||
| -rw-r--r-- | kernel/sched/rt.c | 4 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 32 |
4 files changed, 70 insertions, 46 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5800b0623ff3..daff72f00385 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4200,6 +4200,40 @@ out: return success; } +static bool __task_needs_rq_lock(struct task_struct *p) +{ + unsigned int state = READ_ONCE(p->__state); + + /* + * Since pi->lock blocks try_to_wake_up(), we don't need rq->lock when + * the task is blocked. Make sure to check @state since ttwu() can drop + * locks at the end, see ttwu_queue_wakelist(). + */ + if (state == TASK_RUNNING || state == TASK_WAKING) + return true; + + /* + * Ensure we load p->on_rq after p->__state, otherwise it would be + * possible to, falsely, observe p->on_rq == 0. + * + * See try_to_wake_up() for a longer comment. + */ + smp_rmb(); + if (p->on_rq) + return true; + +#ifdef CONFIG_SMP + /* + * Ensure the task has finished __schedule() and will not be referenced + * anymore. Again, see try_to_wake_up() for a longer comment. + */ + smp_rmb(); + smp_cond_load_acquire(&p->on_cpu, !VAL); +#endif + + return false; +} + /** * task_call_func - Invoke a function on task in fixed state * @p: Process for which the function is to be invoked, can be @current. @@ -4217,28 +4251,12 @@ out: int task_call_func(struct task_struct *p, task_call_f func, void *arg) { struct rq *rq = NULL; - unsigned int state; struct rq_flags rf; int ret; raw_spin_lock_irqsave(&p->pi_lock, rf.flags); - state = READ_ONCE(p->__state); - - /* - * Ensure we load p->on_rq after p->__state, otherwise it would be - * possible to, falsely, observe p->on_rq == 0. - * - * See try_to_wake_up() for a longer comment. - */ - smp_rmb(); - - /* - * Since pi->lock blocks try_to_wake_up(), we don't need rq->lock when - * the task is blocked. Make sure to check @state since ttwu() can drop - * locks at the end, see ttwu_queue_wakelist(). - */ - if (state == TASK_RUNNING || state == TASK_WAKING || p->on_rq) + if (__task_needs_rq_lock(p)) rq = __task_rq_lock(p, &rf); /* @@ -4823,10 +4841,10 @@ static inline void finish_task(struct task_struct *prev) #ifdef CONFIG_SMP -static void do_balance_callbacks(struct rq *rq, struct callback_head *head) +static void do_balance_callbacks(struct rq *rq, struct balance_callback *head) { void (*func)(struct rq *rq); - struct callback_head *next; + struct balance_callback *next; lockdep_assert_rq_held(rq); @@ -4853,15 +4871,15 @@ static void balance_push(struct rq *rq); * This abuse is tolerated because it places all the unlikely/odd cases behind * a single test, namely: rq->balance_callback == NULL. */ -struct callback_head balance_push_callback = { +struct balance_callback balance_push_callback = { .next = NULL, - .func = (void (*)(struct callback_head *))balance_push, + .func = balance_push, }; -static inline struct callback_head * +static inline struct balance_callback * __splice_balance_callbacks(struct rq *rq, bool split) { - struct callback_head *head = rq->balance_callback; + struct balance_callback *head = rq->balance_callback; if (likely(!head)) return NULL; @@ -4883,7 +4901,7 @@ __splice_balance_callbacks(struct rq *rq, bool split) return head; } -static inline struct callback_head *splice_balance_callbacks(struct rq *rq) +static inline struct balance_callback *splice_balance_callbacks(struct rq *rq) { return __splice_balance_callbacks(rq, true); } @@ -4893,7 +4911,7 @@ 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 callback_head *head) +static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) { unsigned long flags; @@ -4910,12 +4928,12 @@ static inline void __balance_callbacks(struct rq *rq) { } -static inline struct callback_head *splice_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 callback_head *head) +static inline void balance_callbacks(struct rq *rq, struct balance_callback *head) { } @@ -6188,7 +6206,7 @@ static void sched_core_balance(struct rq *rq) preempt_enable(); } -static DEFINE_PER_CPU(struct callback_head, core_balance_head); +static DEFINE_PER_CPU(struct balance_callback, core_balance_head); static void queue_core_balance(struct rq *rq) { @@ -7419,7 +7437,7 @@ static int __sched_setscheduler(struct task_struct *p, int oldpolicy = -1, policy = attr->sched_policy; int retval, oldprio, newprio, queued, running; const struct sched_class *prev_class; - struct callback_head *head; + struct balance_callback *head; struct rq_flags rf; int reset_on_fork; int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 86dea6a05267..9ae8f41e3372 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -644,8 +644,8 @@ static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) return rq->online && dl_task(prev); } -static DEFINE_PER_CPU(struct callback_head, dl_push_head); -static DEFINE_PER_CPU(struct callback_head, dl_pull_head); +static DEFINE_PER_CPU(struct balance_callback, dl_push_head); +static DEFINE_PER_CPU(struct balance_callback, dl_pull_head); static void push_dl_tasks(struct rq *); static void pull_dl_task(struct rq *); diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index d869bcf898cc..ed2a47e4ddae 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -410,8 +410,8 @@ static inline int has_pushable_tasks(struct rq *rq) return !plist_head_empty(&rq->rt.pushable_tasks); } -static DEFINE_PER_CPU(struct callback_head, rt_push_head); -static DEFINE_PER_CPU(struct callback_head, rt_pull_head); +static DEFINE_PER_CPU(struct balance_callback, rt_push_head); +static DEFINE_PER_CPU(struct balance_callback, rt_pull_head); static void push_rt_tasks(struct rq *); static void pull_rt_task(struct rq *); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1644242ecd11..a4a20046e586 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -938,6 +938,12 @@ struct uclamp_rq { DECLARE_STATIC_KEY_FALSE(sched_uclamp_used); #endif /* CONFIG_UCLAMP_TASK */ +struct rq; +struct balance_callback { + struct balance_callback *next; + void (*func)(struct rq *rq); +}; + /* * This is the main, per-CPU runqueue data structure. * @@ -1036,7 +1042,7 @@ struct rq { unsigned long cpu_capacity; unsigned long cpu_capacity_orig; - struct callback_head *balance_callback; + struct balance_callback *balance_callback; unsigned char nohz_idle_balance; unsigned char idle_balance; @@ -1182,6 +1188,14 @@ static inline bool is_migration_disabled(struct task_struct *p) #endif } +DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); + +#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) +#define this_rq() this_cpu_ptr(&runqueues) +#define task_rq(p) cpu_rq(task_cpu(p)) +#define cpu_curr(cpu) (cpu_rq(cpu)->curr) +#define raw_rq() raw_cpu_ptr(&runqueues) + struct sched_group; #ifdef CONFIG_SCHED_CORE static inline struct cpumask *sched_group_span(struct sched_group *sg); @@ -1269,7 +1283,7 @@ static inline bool sched_group_cookie_match(struct rq *rq, return true; for_each_cpu_and(cpu, sched_group_span(group), p->cpus_ptr) { - if (sched_core_cookie_match(rq, p)) + if (sched_core_cookie_match(cpu_rq(cpu), p)) return true; } return false; @@ -1384,14 +1398,6 @@ static inline void update_idle_core(struct rq *rq) static inline void update_idle_core(struct rq *rq) { } #endif -DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); - -#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) -#define this_rq() this_cpu_ptr(&runqueues) -#define task_rq(p) cpu_rq(task_cpu(p)) -#define cpu_curr(cpu) (cpu_rq(cpu)->curr) -#define raw_rq() raw_cpu_ptr(&runqueues) - #ifdef CONFIG_FAIR_GROUP_SCHED static inline struct task_struct *task_of(struct sched_entity *se) { @@ -1544,7 +1550,7 @@ struct rq_flags { #endif }; -extern struct callback_head balance_push_callback; +extern struct balance_callback balance_push_callback; /* * Lockdep annotation that avoids accidental unlocks; it's like a @@ -1724,7 +1730,7 @@ init_numa_balancing(unsigned long clone_flags, struct task_struct *p) static inline void queue_balance_callback(struct rq *rq, - struct callback_head *head, + struct balance_callback *head, void (*func)(struct rq *rq)) { lockdep_assert_rq_held(rq); @@ -1737,7 +1743,7 @@ queue_balance_callback(struct rq *rq, if (unlikely(head->next || rq->balance_callback == &balance_push_callback)) return; - head->func = (void (*)(struct callback_head *))func; + head->func = func; head->next = rq->balance_callback; rq->balance_callback = head; } |