linux-kernel - Re: [PATCH 3/3] workqueue: add a check point in pwq_activate_delayed

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Message-ID: <20130605071754.GA7303@mtj.dyndns.org>
Date:	Wed, 5 Jun 2013 00:17:54 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] workqueue: add a check point in
 pwq_activate_delayed_work()

On Wed, Jun 05, 2013 at 03:11:35PM +0800, Michael Wang wrote:
> get_work_pwq() is possible to return NULL, add a check point for that in
> the context inside pwq_activate_delayed_work().
> 
> CC: Tejun Heo <tj@...nel.org>
> Signed-off-by: Michael Wang <wangyun@...ux.vnet.ibm.com>
> ---
>  kernel/workqueue.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index ee8e29a..ea2ec38 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1072,6 +1072,7 @@ static void put_pwq_unlocked(struct pool_workqueue *pwq)
>  static void pwq_activate_delayed_work(struct work_struct *work)
>  {
>  	struct pool_workqueue *pwq = get_work_pwq(work);
> +	BUG_ON(!pwq);

pwq deref right below is gonna crash anyway and it's not like that
crash is gonna difficult to identify.  How is this an improvement?

Thanks.

-- 
tejun
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