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sched: Also serialize ttwu_local() with p->pi_lock 

Since we now serialize ttwu() using p->pi_lock, we also need to
serialize ttwu_local() using that, otherwise, once we drop the
rq->lock from ttwu() it can race with ttwu_local().

Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110405152729.192366907@chello.nl
hifive-unleashed-5.1
Peter Zijlstra 2011-04-05 17:23:50 +02:00 committed by Ingo Molnar
parent a8e4f2eaec
commit 2acca55ed9
1 changed files with 19 additions and 12 deletions
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31
kernel/sched.c
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@ -2566,9 +2566,9 @@ out:
* try_to_wake_up_local - try to wake up a local task with rq lock held
* @p: the thread to be awakened
*
* Put @p on the run-queue if it's not already there. The caller must
* Put @p on the run-queue if it's not already there. The caller must
* ensure that this_rq() is locked, @p is bound to this_rq() and not
* the current task. this_rq() stays locked over invocation.
* the current task.
*/
static void try_to_wake_up_local(struct task_struct *p)
{
@ -2578,14 +2578,22 @@ static void try_to_wake_up_local(struct task_struct *p)
BUG_ON(p == current);
lockdep_assert_held(&rq->lock);
if (!raw_spin_trylock(&p->pi_lock)) {
raw_spin_unlock(&rq->lock);
raw_spin_lock(&p->pi_lock);
raw_spin_lock(&rq->lock);
}
if (!(p->state & TASK_NORMAL))
return;
goto out;
if (!p->on_rq)
ttwu_activate(rq, p, ENQUEUE_WAKEUP);
ttwu_post_activation(p, rq, 0);
ttwu_stat(rq, p, smp_processor_id(), 0);
out:
raw_spin_unlock(&p->pi_lock);
}
/**
@ -4114,11 +4122,13 @@ need_resched:
if (unlikely(signal_pending_state(prev->state, prev))) {
prev->state = TASK_RUNNING;
} else {
deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
/*
* If a worker is going to sleep, notify and
* ask workqueue whether it wants to wake up a
* task to maintain concurrency. If so, wake
* up the task.
* If a worker went to sleep, notify and ask workqueue
* whether it wants to wake up a task to maintain
* concurrency.
*/
if (prev->flags & PF_WQ_WORKER) {
struct task_struct *to_wakeup;
@ -4128,12 +4138,9 @@ need_resched:
try_to_wake_up_local(to_wakeup);
}
deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
/*
* If we are going to sleep and we have plugged IO queued, make
* sure to submit it to avoid deadlocks.
* If we are going to sleep and we have plugged IO
* queued, make sure to submit it to avoid deadlocks.
*/
if (blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);