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Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull scheduler fix from Thomas Gleixner:
 "Fix a potential deadlock versus hrtimers"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix HRTICK
This commit is contained in:
Linus Torvalds 2013-07-13 15:37:57 -07:00
commit f8acc450e1
1 changed files with 11 additions and 9 deletions
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20
kernel/sched/core.c
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@ -370,13 +370,6 @@ static struct rq *this_rq_lock(void)
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
*
* Its all a bit involved since we cannot program an hrt while holding the
* rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
* reschedule event.
*
* When we get rescheduled we reprogram the hrtick_timer outside of the
* rq->lock.
*/
static void hrtick_clear(struct rq *rq)
@ -404,6 +397,15 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer)
}
#ifdef CONFIG_SMP
static int __hrtick_restart(struct rq *rq)
{
struct hrtimer *timer = &rq->hrtick_timer;
ktime_t time = hrtimer_get_softexpires(timer);
return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
}
/*
* called from hardirq (IPI) context
*/
@ -412,7 +414,7 @@ static void __hrtick_start(void *arg)
struct rq *rq = arg;
raw_spin_lock(&rq->lock);
hrtimer_restart(&rq->hrtick_timer);
__hrtick_restart(rq);
rq->hrtick_csd_pending = 0;
raw_spin_unlock(&rq->lock);
}
@ -430,7 +432,7 @@ void hrtick_start(struct rq *rq, u64 delay)
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
hrtimer_restart(timer);
__hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
__smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;