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From: Yong Zhang <yong.zhang0@gmail.com>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
	netdev@vger.kernel.org, Ben Dooks <ben-linux@fluff.org>
Subject: Re: [PATCH 1/2] workqueue: Catch more locking problems with flush_work()
Date: Fri, 20 Apr 2012 13:26:33 +0800	[thread overview]
Message-ID: <20120420052633.GA16219@zhy> (raw)
In-Reply-To: <4F905B30.4080501@codeaurora.org>

On Thu, Apr 19, 2012 at 11:36:32AM -0700, Stephen Boyd wrote:
> Does looking at the second patch help? Basically schedule_work() can run
> the callback right between the time the mutex is acquired and
> flush_work() is called:
> 
> CPU0                        CPU1
> 
> <irq>
>   schedule_work()           mutex_lock(&mutex)
> <irq return>
>     my_work()               flush_work() 
>       mutex_lock(&mutex)    
>       <deadlock>

Get you point. It is a problem. But your patch could introduece false
positive since when flush_work() is called that very work may finish
running already.

So I think we need the lock_map_acquire()/lock_map_release() only when
the work is under processing, no?

Thanks,
Yong

  reply	other threads:[~2012-04-20  5:33 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-19  3:25 [PATCH 1/2] workqueue: Catch more locking problems with flush_work() Stephen Boyd
2012-04-19  3:25 ` [PATCH 2/2] ks8851: Fix mutex deadlock in ks8851_net_stop() Stephen Boyd
2012-04-21 19:34   ` David Miller
2012-04-19  8:10 ` [PATCH 1/2] workqueue: Catch more locking problems with flush_work() Yong Zhang
2012-04-19 18:36   ` Stephen Boyd
2012-04-20  5:26     ` Yong Zhang [this message]
2012-04-20  6:01       ` Yong Zhang
2012-04-20  6:26         ` Stephen Boyd
2012-04-20  7:18           ` Yong Zhang
2012-04-20  8:18             ` Stephen Boyd
2012-04-20  8:32               ` Yong Zhang
2012-04-21  0:32                 ` Yong Zhang
2012-04-19 15:28 ` Tejun Heo
2012-04-19 18:10   ` Stephen Boyd
2012-04-20 17:35     ` Tejun Heo
2012-04-20 23:15       ` Stephen Boyd
2012-04-21  0:28       ` [PATCHv2] " Stephen Boyd
2012-04-21  0:34         ` Yong Zhang
2012-04-23 18:07         ` Tejun Heo

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