From 36aa9dfc39bf473780439f5629c30f59d677e793 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 9 May 2007 02:34:08 -0700 Subject: [PATCH] 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: Oleg Nesterov Cc: Srivatsa Vaddagiri Cc: "Pallipadi, Venkatesh" Cc: Gautham shenoy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/workqueue.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 1d1933cf377..398c34ff6a5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -625,17 +625,12 @@ EXPORT_SYMBOL_GPL(__create_workqueue); static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu) { - struct cpu_workqueue_struct *cwq; - unsigned long flags; - struct task_struct *p; + struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); - cwq = per_cpu_ptr(wq->cpu_wq, cpu); - spin_lock_irqsave(&cwq->lock, flags); - p = cwq->thread; - cwq->thread = NULL; - spin_unlock_irqrestore(&cwq->lock, flags); - if (p) - kthread_stop(p); + if (cwq->thread) { + kthread_stop(cwq->thread); + cwq->thread = NULL; + } } /**