Commit 4cd57f97 authored Mar 31, 2015 by Juri Lelli Committed by Ingo Molnar Apr 02, 2015

sched/deadline: Always enqueue on previous rq when dl_task_timer() fires



dl_task_timer() may fire on a different rq from where a task was removed
after throttling. Since the call path is:

  dl_task_timer() ->
    enqueue_task_dl() ->
      enqueue_dl_entity() ->
        replenish_dl_entity()

and replenish_dl_entity() uses dl_se's rq, we can't use current's rq
in dl_task_timer(), but we need to lock the task's previous one.

Tested-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kirill Tkhai <ktkhai@parallels.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Fixes: 3960c8c0 ("sched: Make dl_task_time() use task_rq_lock()")
Link: http://lkml.kernel.org/r/1427792017-7356-1-git-send-email-juri.lelli@arm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 07c54f7a

kernel/sched/deadline.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -514,7 +514,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
		unsigned long flags;
		struct rq *rq;

		rq = task_rq_lock(current, &flags);
		rq = task_rq_lock(p, &flags);

		/*
		* We need to take care of several possible races here:
		@@ -569,7 +569,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
		push_dl_task(rq);
		#endif
		unlock:
		task_rq_unlock(rq, current, &flags);
		task_rq_unlock(rq, p, &flags);

		return HRTIMER_NORESTART;
		}

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