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sched/deadline: Fix stale yield state

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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 67dfa1b756 ("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: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2014-11-26 08:44:03 +08:00 • committed by Ingo Molnar
commit 1019a359d3
1 changed files with 19 additions and 19 deletions
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38
kernel/sched/deadline.c
View file

@ -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;
}
/*
@ -536,23 +541,19 @@ again:
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);
else
resched_curr(rq);
enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
if (dl_task(rq->curr))
check_preempt_curr_dl(rq, p, 0);
else
resched_curr(rq);
#ifdef CONFIG_SMP
/*
* Queueing this task back might have overloaded rq,
* check if we need to kick someone away.
*/
if (has_pushable_dl_tasks(rq))
push_dl_task(rq);
/*
* Queueing this task back might have overloaded rq,
* check if we need to kick someone away.
*/
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)) {
dl_se->dl_throttled = 1;
__dequeue_task_dl(rq, curr, 0);
if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))
dl_se->dl_throttled = 1;
else
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);