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sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task()

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Do not call dequeue_pushable_task() when failing to push an eligible
task, as it remains pushable, merely not at this particular moment.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Mike Galbraith <mgalbraith@gmx.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Link: http://lkml.kernel.org/r/1306895385.4791.26.camel@marge.simson.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Hillf Danton 2011-06-16 21:55:20 -04:00 committed by Ingo Molnar
parent 0835471697
commit 311e800e16
1 changed files with 8 additions and 7 deletions
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15
kernel/sched_rt.c
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@ -1394,6 +1394,7 @@ static int push_rt_task(struct rq *rq)
{ {
struct task_struct *next_task; struct task_struct *next_task;
struct rq *lowest_rq; struct rq *lowest_rq;
int ret = 0;
if (!rq->rt.overloaded) if (!rq->rt.overloaded)
return 0; return 0;
@ -1426,7 +1427,7 @@ retry:
if (!lowest_rq) { if (!lowest_rq) {
struct task_struct *task; struct task_struct *task;
/* /*
* find lock_lowest_rq releases rq->lock * find_lock_lowest_rq releases rq->lock
* so it is possible that next_task has migrated. * so it is possible that next_task has migrated.
* *
* We need to make sure that the task is still on the same * We need to make sure that the task is still on the same
@ -1436,12 +1437,11 @@ retry:
task = pick_next_pushable_task(rq); task = pick_next_pushable_task(rq);
if (task_cpu(next_task) == rq->cpu && task == next_task) { if (task_cpu(next_task) == rq->cpu && task == next_task) {
/* /*
* If we get here, the task hasn't moved at all, but * The task hasn't migrated, and is still the next
* it has failed to push. We will not try again, * eligible task, but we failed to find a run-queue
* since the other cpus will pull from us when they * to push it to. Do not retry in this case, since
* are ready. * other cpus will pull from us when ready.
*/ */
dequeue_pushable_task(rq, next_task);
goto out; goto out;
} }
@ -1460,6 +1460,7 @@ retry:
deactivate_task(rq, next_task, 0); deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu); set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0); activate_task(lowest_rq, next_task, 0);
ret = 1;
resched_task(lowest_rq->curr); resched_task(lowest_rq->curr);
@ -1468,7 +1469,7 @@ retry:
out: out:
put_task_struct(next_task); put_task_struct(next_task);
return 1; return ret;
} }
static void push_rt_tasks(struct rq *rq) static void push_rt_tasks(struct rq *rq)