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Commit 36aa9dfc authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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workqueue: don't clear cwq->thread until it exits 



Pointed out by Srivatsa Vaddagiri.

cleanup_workqueue_thread() sets cwq->thread = NULL and does kthread_stop().
This breaks the "if (cwq->thread == current)" logic in flush_cpu_workqueue()
and leads to deadlock.

Kill the thead first, then clear cwq->thread. workqueue_mutex protects us
from create_workqueue_thread() so we don't need cwq->lock.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: Gautham shenoy <ego@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d721304d

kernel/workqueue.c

+5 −10
Original line number Original line Diff line number Diff line
@@ -625,17 +625,12 @@ EXPORT_SYMBOL_GPL(__create_workqueue); 




static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)

static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)

{

{

	struct cpu_workqueue_struct *cwq;

	struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);

	unsigned long flags;

	struct task_struct *p;





	cwq = per_cpu_ptr(wq->cpu_wq, cpu);

	if (cwq->thread) {

	spin_lock_irqsave(&cwq->lock, flags);

		kthread_stop(cwq->thread);

	p = cwq->thread;

		cwq->thread = NULL;

		cwq->thread = NULL;

	spin_unlock_irqrestore(&cwq->lock, flags);

	}

	if (p)

		kthread_stop(p);

}

}





/**

/**