From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] blk-mq: fix race between timeout and queue_rq
Date: Wed, 17 Sep 2014 18:44:00 +0200 [thread overview]
Message-ID: <20140917164400.GA18472@lst.de> (raw)
In-Reply-To: <1410947278-15733-2-git-send-email-ming.lei@canonical.com>
On Wed, Sep 17, 2014 at 05:47:57PM +0800, Ming Lei wrote:
> Either the request is from requeue or just being allocated from
> tag pool, its REQ_ATOM_STARTED flag has been cleared already, so
> don't test it in blk_mq_start_request().
>
> One memory barrier is needed between writing rq->deadline and
> setting REQ_ATOM_STARTED so that timeout can't happen too early
> if timeout handler reads obsolete rq->deadline caused by out
> of order of the two writes.
Looks reasonable to me,
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2014-09-17 16:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-17 9:47 [PATCH 0/2] blk-mq: fix race between timeout and queue_rq Ming Lei
2014-09-17 9:47 ` [PATCH 1/2] " Ming Lei
2014-09-17 16:44 ` Christoph Hellwig [this message]
2014-09-17 9:47 ` [PATCH 2/2] blk-mq: remove unnecessary blk_clear_rq_complete() Ming Lei
2014-09-17 16:48 ` Christoph Hellwig
2014-09-18 1:33 ` Ming Lei
2014-09-18 16:26 ` Christoph Hellwig
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