linux-kernel - Re: [PATCH] workqueue: detect uninitated work

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Message-ID: <20150309062243.GL13283@htj.duckdns.org>
Date:	Mon, 9 Mar 2015 02:22:43 -0400
From:	Tejun Heo <tj@...nel.org>
To:	"Du, Changbin" <changbin.du@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] workqueue: detect uninitated work_struct and BUG() if
 true

On Mon, Mar 09, 2015 at 04:43:11AM +0000, Du, Changbin wrote:
> From cdebb88ac0fb3f900ef28f28ccb4a12159c295db Mon Sep 17 00:00:00 2001
> From: "Du, Changbin" <changbin.du@...il.com>
> Date: Mon, 9 Mar 2015 12:06:43 +0800
> Subject: [PATCH] workqueue: detect uninitated work_struct and BUG() if true
> 
> Recently I encounter a driver issue that caused by missing initializing
> the work_struct. Then the work never get executed and stay in workqueue
> forever. This take me some time to locate the error. This issue can be
> seen early if detect it when queuing a work.
> 
> Signed-off-by: Du, Changbin <changbin.du@...el.com>
> ---
>  kernel/workqueue.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index f288493..5c1a5bc 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1295,6 +1295,9 @@ static void __queue_work(int cpu, struct workqueue_struct *wq,
>  	 */
>  	WARN_ON_ONCE(!irqs_disabled());
>  
> +	if (!work->func)
> +		BUG();
> +
>  	debug_work_activate(work);

Can't this be part of the debug_work mechanism?  I'm a bit wary of
adding essentially arbitrary checks.  I'd much prefer if it gets gated
by debug config somehow.

Thanks.

-- 
tejun
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