diff options
author | Gary S. Robertson <gary.robertson@linaro.org> | 2016-01-20 15:36:59 -0600 |
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committer | Gary S. Robertson <gary.robertson@linaro.org> | 2016-01-20 15:36:59 -0600 |
commit | 370e05d463d66eaada3b4bb9266f019563920eb0 (patch) | |
tree | 348834a36436338eea1e9f17f1823cae213f92fc /kernel/sched/core.c | |
parent | f93328edc6d139b9b1b5ed6944f7b80b8699cdf7 (diff) | |
parent | 906d9eadd3b6698fa6ceb9bcdf41da6aa56d0a24 (diff) |
Merge tag 'lsk-v4.1-15.12-rt' of http://git.linaro.org/kernel/linux-linaro-stable into linux-linaro-lng-v4.1-rtlinux-lng-preempt-rt-4.1.14-2016.03linux-lng-preempt-rt-4.1.14-2016.02linux-lng-preempt-rt-4.1.14-2016.01linux-linaro-lng-v4.1-rt
LSK RT 15.12 v4.1
Conflicts:
linaro/configs/linaro-base.conf
linaro/configs/preempt-rt.conf
linaro/configs/vexpress64.conf
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r-- | kernel/sched/core.c | 47 |
1 files changed, 32 insertions, 15 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5f032b682fca..26717308d9a3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1558,9 +1558,9 @@ static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) { check_preempt_curr(rq, p, wake_flags); - trace_sched_wakeup(p, true); - p->state = TASK_RUNNING; + trace_sched_wakeup(p); + #ifdef CONFIG_SMP if (p->sched_class->task_woken) p->sched_class->task_woken(rq, p); @@ -1784,6 +1784,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) if (!(wake_flags & WF_LOCK_SLEEPER)) p->saved_state = TASK_RUNNING; + trace_sched_waking(p); + success = 1; /* we're going to change ->state */ cpu = task_cpu(p); @@ -2188,7 +2190,7 @@ void wake_up_new_task(struct task_struct *p) rq = __task_rq_lock(p); activate_task(rq, p, 0); p->on_rq = TASK_ON_RQ_QUEUED; - trace_sched_wakeup_new(p, true); + trace_sched_wakeup_new(p); check_preempt_curr(rq, p, WF_FORK); #ifdef CONFIG_SMP if (p->sched_class->task_woken) @@ -2311,11 +2313,11 @@ static struct rq *finish_task_switch(struct task_struct *prev) * If a task dies, then it sets TASK_DEAD in tsk->state and calls * schedule one last time. The schedule call will never return, and * the scheduled task must drop that reference. - * The test for TASK_DEAD must occur while the runqueue locks are - * still held, otherwise prev could be scheduled on another cpu, die - * there before we look at prev->state, and then the reference would - * be dropped twice. - * Manfred Spraul <manfred@colorfullife.com> + * + * We must observe prev->state before clearing prev->on_cpu (in + * finish_lock_switch), otherwise a concurrent wakeup can get prev + * running on another CPU and we could rave with its RUNNING -> DEAD + * transition, resulting in a double drop. */ prev_state = prev->state; vtime_task_switch(prev); @@ -2456,13 +2458,20 @@ unsigned long nr_running(void) /* * Check if only the current task is running on the cpu. + * + * Caution: this function does not check that the caller has disabled + * preemption, thus the result might have a time-of-check-to-time-of-use + * race. The caller is responsible to use it correctly, for example: + * + * - from a non-preemptable section (of course) + * + * - from a thread that is bound to a single CPU + * + * - in a loop with very short iterations (e.g. a polling loop) */ bool single_task_running(void) { - if (cpu_rq(smp_processor_id())->nr_running == 1) - return true; - else - return false; + return raw_rq()->nr_running == 1; } EXPORT_SYMBOL(single_task_running); @@ -4489,7 +4498,7 @@ SYSCALL_DEFINE0(sched_yield) int __sched _cond_resched(void) { - if (should_resched()) { + if (should_resched(0)) { preempt_schedule_common(); return 1; } @@ -4507,7 +4516,7 @@ EXPORT_SYMBOL(_cond_resched); */ int __cond_resched_lock(spinlock_t *lock) { - int resched = should_resched(); + int resched = should_resched(PREEMPT_LOCK_OFFSET); int ret = 0; lockdep_assert_held(lock); @@ -4530,7 +4539,7 @@ int __sched __cond_resched_softirq(void) { BUG_ON(!in_softirq()); - if (should_resched()) { + if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { local_bh_enable(); preempt_schedule_common(); local_bh_disable(); @@ -5686,6 +5695,14 @@ static int sched_cpu_active(struct notifier_block *nfb, case CPU_STARTING: set_cpu_rq_start_time(); return NOTIFY_OK; + case CPU_ONLINE: + /* + * At this point a starting CPU has marked itself as online via + * set_cpu_online(). But it might not yet have marked itself + * as active, which is essential from here on. + * + * Thus, fall-through and help the starting CPU along. + */ case CPU_DOWN_FAILED: set_cpu_active((long)hcpu, true); return NOTIFY_OK; |