Date: Fri, 30 Nov 2012 23:15:50 -0500 (EST)
From: Anders Kaseorg <andersk@MIT.EDU>
To: Tejun Heo <tj@kernel.org>
cc: Herbert Xu <herbert@gondor.hengli.com.au>,
	"John W. Linville" <linville@tuxdriver.com>,
	netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: Wireless regression in workqueue: use mod_delayed_work() instead
 of __cancel + queue
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On Fri, 30 Nov 2012, Tejun Heo wrote:
> Hey, again.
> 
> Can you please test whether the following patch makes any difference?
> 
> Thanks!
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 042d221..26368ef 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1477,7 +1477,10 @@ bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
>  	} while (unlikely(ret == -EAGAIN));
>  
>  	if (likely(ret >= 0)) {
> -		__queue_delayed_work(cpu, wq, dwork, delay);
> +		if (!delay)
> +			__queue_work(cpu, wq, &dwork->work);
> +		else
> +			__queue_delayed_work(cpu, wq, dwork, delay);
>  		local_irq_restore(flags);
>  	}
>  

Yes.  I tested that both directly on top of the bad commit, and on 
v3.7-rc7, and it fixes the bug in both cases.

Thanks,
Anders