linux-kernel - Re: [PATCH] workqueue: sanity check pool->cpu in wq_worker

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Message-ID: <20140619163209.GN26904@htj.dyndns.org>
Date:	Thu, 19 Jun 2014 12:32:09 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] workqueue: sanity check pool->cpu in wq_worker_sleeping()

On Tue, Jun 03, 2014 at 03:33:08PM +0800, Lai Jiangshan wrote:
> In theory, pool->cpu is equals to @cpu in wq_worker_sleeping() after
> worker->flags is checked.
> 
> And "pool->cpu != cpu" sanity check will help us if something wrong.
> 
> Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
> ---
>  kernel/workqueue.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 9f53abd..61381a2 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -843,7 +843,7 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
>  	pool = worker->pool;
>  
>  	/* this can only happen on the local cpu */
> -	if (WARN_ON_ONCE(cpu != raw_smp_processor_id()))
> +	if (WARN_ON_ONCE(cpu != raw_smp_processor_id() || pool->cpu != cpu))

Hmmm... yeah, this can catch work functions hijacking and binding
per-cpu worker to another cpu.

Applied to wq/for-3.17.

Thanks.

-- 
tejun
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