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Commit 1019a359 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/deadline: Fix stale yield state 



When we fail to start the deadline timer in update_curr_dl(), we
forget to clear ->dl_yielded, resulting in wrecked time keeping.

Since the natural place to clear both ->dl_yielded and ->dl_throttled
is in replenish_dl_entity(); both are after all waiting for that event;
make it so.

Luckily since 67dfa1b7 ("sched/deadline: Implement
cancel_dl_timer() to use in switched_from_dl()") the
task_on_rq_queued() condition in dl_task_timer() must be true, and can
therefore call enqueue_task_dl() unconditionally.

Reported-by: default avatarWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1416962647-76792-4-git-send-email-wanpeng.li@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a7bebf48

kernel/sched/deadline.c

+19 −19
Original line number Diff line number Diff line
@@ -350,6 +350,11 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se, 
		dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;

		dl_se->runtime = pi_se->dl_runtime;

	}



	if (dl_se->dl_yielded)

		dl_se->dl_yielded = 0;

	if (dl_se->dl_throttled)

		dl_se->dl_throttled = 0;

}



/*
@@ -536,9 +541,6 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) 


	sched_clock_tick();

	update_rq_clock(rq);

	dl_se->dl_throttled = 0;

	dl_se->dl_yielded = 0;

	if (task_on_rq_queued(p)) {

	enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);

	if (dl_task(rq->curr))

		check_preempt_curr_dl(rq, p, 0);
@@ -552,7 +554,6 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) 
	if (has_pushable_dl_tasks(rq))

		push_dl_task(rq);

#endif

	}

unlock:

	raw_spin_unlock(&rq->lock);
@@ -613,10 +614,9 @@ static void update_curr_dl(struct rq *rq) 


	dl_se->runtime -= dl_se->dl_yielded ? 0 : delta_exec;

	if (dl_runtime_exceeded(rq, dl_se)) {

		__dequeue_task_dl(rq, curr, 0);

		if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))

		dl_se->dl_throttled = 1;

		else

		__dequeue_task_dl(rq, curr, 0);

		if (unlikely(!start_dl_timer(dl_se, curr->dl.dl_boosted)))

			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);



		if (!is_leftmost(curr, &rq->dl))
@@ -853,7 +853,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) 
	 * its rq, the bandwidth timer callback (which clearly has not

	 * run yet) will take care of this.

	 */

	if (p->dl.dl_throttled)

	if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH))

		return;



	enqueue_dl_entity(&p->dl, pi_se, flags);