From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [PATCH 3/5] MTD: blktrans: fix a race vs kthread_stop.
From: David Woodhouse <dwmw2@infradead.org>
To: Maxim Levitsky <maximlevitsky@gmail.com>
In-Reply-To: <1287156047-17439-4-git-send-email-maximlevitsky@gmail.com>
References: <1287156047-17439-1-git-send-email-maximlevitsky@gmail.com>
	<1287156047-17439-4-git-send-email-maximlevitsky@gmail.com>
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Date: Mon, 25 Oct 2010 01:31:51 +0100
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Cc: linux-mtd@lists.infradead.org, Andrew Morton <akpm@linux-foundation.org>,
	Maxim Levitsky <maximlevisky@gmail.com>,
	Maciej Rutecki <maciej.rutecki@gmail.com>
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On Fri, 2010-10-15 at 17:20 +0200, Maxim Levitsky wrote:
> There is small race window that could make kthread_stop hang forever.
> I found that while hacking the IR subsystem.
> 
> Signed-off-by: Maxim Levitsky <maximlevisky@gmail.com>
> ---
>  drivers/mtd/mtd_blkdevs.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> index 040c2d9..a919587 100644
> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -133,6 +133,10 @@ static int mtd_blktrans_thread(void *arg)
>  
>  		if (!req && !(req = blk_fetch_request(rq))) {
>  			set_current_state(TASK_INTERRUPTIBLE);
> +
> +			if (kthread_should_stop())
> +				set_current_state(TASK_RUNNING);
> +
>  			spin_unlock_irq(rq->queue_lock);
>  			schedule();
>  			spin_lock_irq(rq->queue_lock);


Shouldn't we add a break in there too, so it immediately breaks out of
the loop (with the lock held)?

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation