Commit f8acc450 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

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
parents 505608d2 971ee28c

kernel/sched/core.c

+11 −9
Original line number Diff line number Diff line
@@ -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;