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sched/deadline: Fix switching to -deadline

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Fix a bug introduced in:

  72f9f3fdc9 ("sched/deadline: Remove dl_new from struct sched_dl_entity")

After that commit, when switching to -deadline if the scheduling
deadline of a task is in the past then switched_to_dl() calls
setup_new_entity() to properly initialize the scheduling deadline
and runtime.

The problem is that the task is enqueued _before_ having its parameters
initialized by setup_new_entity(), and this can cause problems.
For example, a task with its out-of-date deadline in the past will
potentially be enqueued as the highest priority one; however, its
adjusted deadline may not be the earliest one.

This patch fixes the problem by initializing the task's parameters before
enqueuing it.

Signed-off-by: luca abeni <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Daniel Bristot de Oliveira <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Luca Abeni 2017-09-07 12:09:29 +02:00 • committed by Ingo Molnar
commit 295d6d5e37
1 changed files with 4 additions and 7 deletions
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11
kernel/sched/deadline.c
View file

@ -1364,6 +1364,10 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se,
update_dl_entity(dl_se, pi_se);
} else if (flags & ENQUEUE_REPLENISH) {
replenish_dl_entity(dl_se, pi_se);
} else if ((flags & ENQUEUE_RESTORE) &&
dl_time_before(dl_se->deadline,
rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
setup_new_dl_entity(dl_se);
}
__enqueue_dl_entity(dl_se);
@ -2255,13 +2259,6 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
return;
}
/*
* If p is boosted we already updated its params in
* rt_mutex_setprio()->enqueue_task(..., ENQUEUE_REPLENISH),
* p's deadline being now already after rq_clock(rq).
*/
if (dl_time_before(p->dl.deadline, rq_clock(rq)))
setup_new_dl_entity(&p->dl);
if (rq->curr != p) {
#ifdef CONFIG_SMP