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
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@ -2566,9 +2566,9 @@ out:
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* try_to_wake_up_local - try to wake up a local task with rq lock held
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* @p: the thread to be awakened
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*
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* Put @p on the run-queue if it's not already there. The caller must
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* Put @p on the run-queue if it's not already there. The caller must
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* ensure that this_rq() is locked, @p is bound to this_rq() and not
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* the current task. this_rq() stays locked over invocation.
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* the current task.
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*/
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static void try_to_wake_up_local(struct task_struct *p)
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{
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@ -2578,14 +2578,22 @@ static void try_to_wake_up_local(struct task_struct *p)
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BUG_ON(p == current);
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lockdep_assert_held(&rq->lock);
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if (!raw_spin_trylock(&p->pi_lock)) {
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raw_spin_unlock(&rq->lock);
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raw_spin_lock(&p->pi_lock);
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raw_spin_lock(&rq->lock);
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}
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if (!(p->state & TASK_NORMAL))
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return;
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goto out;
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if (!p->on_rq)
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ttwu_activate(rq, p, ENQUEUE_WAKEUP);
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ttwu_post_activation(p, rq, 0);
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ttwu_stat(rq, p, smp_processor_id(), 0);
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out:
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raw_spin_unlock(&p->pi_lock);
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}
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/**
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@ -4114,11 +4122,13 @@ need_resched:
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if (unlikely(signal_pending_state(prev->state, prev))) {
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prev->state = TASK_RUNNING;
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} else {
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deactivate_task(rq, prev, DEQUEUE_SLEEP);
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prev->on_rq = 0;
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/*
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* If a worker is going to sleep, notify and
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* ask workqueue whether it wants to wake up a
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* task to maintain concurrency. If so, wake
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* up the task.
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* If a worker went to sleep, notify and ask workqueue
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* whether it wants to wake up a task to maintain
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* concurrency.
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*/
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if (prev->flags & PF_WQ_WORKER) {
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struct task_struct *to_wakeup;
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@ -4128,12 +4138,9 @@ need_resched:
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try_to_wake_up_local(to_wakeup);
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}
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deactivate_task(rq, prev, DEQUEUE_SLEEP);
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prev->on_rq = 0;
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/*
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* If we are going to sleep and we have plugged IO queued, make
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* sure to submit it to avoid deadlocks.
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* If we are going to sleep and we have plugged IO
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* queued, make sure to submit it to avoid deadlocks.
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*/
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if (blk_needs_flush_plug(prev)) {
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raw_spin_unlock(&rq->lock);
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