Messages in this thread |  | | | Date | Tue, 10 Feb 2009 12:53:44 -0800 | | From | Andrew Morton <> | | Subject | Re: [PATCH 2/3] workqueue: not allow recursion run_workqueue |
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On Fri, 06 Feb 2009 09:46:29 +0800 Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
> Hi, Ingo > > This is new changelog, I didn't change the patch, > except use WARN_ON instead BUG_ON. > > Thanks, Lai > > From: Lai Jiangshan <laijs@cn.fujitsu.com> > > 1) lockdep will complain when recursion run_workqueue() > 2) The recursive implement of run_workqueue() makes flush_workqueue() > and it's doc are inconsistent. It may hide deadlock and other bugs. > 3) recursion run_workqueue() will poison cwq->current_work, > but flush_work() and __cancel_work_timer() ...etc. need > reliable cwq->current_work. > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index 2f44583..1129cde 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -48,8 +48,6 @@ struct cpu_workqueue_struct { > > struct workqueue_struct *wq; > struct task_struct *thread; > - > - int run_depth; /* Detect run_workqueue() recursion depth */ > } ____cacheline_aligned; > > /* > @@ -262,13 +260,6 @@ EXPORT_SYMBOL_GPL(queue_delayed_work_on); > static void run_workqueue(struct cpu_workqueue_struct *cwq) > { > spin_lock_irq(&cwq->lock); > - cwq->run_depth++; > - if (cwq->run_depth > 3) { > - /* morton gets to eat his hat */ > - printk("%s: recursion depth exceeded: %d\n", > - __func__, cwq->run_depth); > - dump_stack(); > - }
I never did get to eat my hat.
Do we know of any cases where there was ever any recursion here? Even single-level recursion?
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