From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60352 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031831AbdADUMs (ORCPT ); Wed, 4 Jan 2017 15:12:48 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bart Van Assche , Mike Snitzer Subject: [PATCH 4.9 63/83] dm rq: fix a race condition in rq_completed() Date: Wed, 4 Jan 2017 21:06:55 +0100 Message-Id: <20170104200449.092657913@linuxfoundation.org> In-Reply-To: <20170104200446.541604386@linuxfoundation.org> References: <20170104200446.541604386@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bart Van Assche commit d15bb3a6467e102e60d954aadda5fb19ce6fd8ec upstream. It is required to hold the queue lock when calling blk_run_queue_async() to avoid that a race between blk_run_queue_async() and blk_cleanup_queue() is triggered. Signed-off-by: Bart Van Assche Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-rq.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -226,6 +226,9 @@ static void rq_end_stats(struct mapped_d */ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) { + struct request_queue *q = md->queue; + unsigned long flags; + atomic_dec(&md->pending[rw]); /* nudge anyone waiting on suspend queue */ @@ -238,8 +241,11 @@ static void rq_completed(struct mapped_d * back into ->request_fn() could deadlock attempting to grab the * queue lock again. */ - if (!md->queue->mq_ops && run_queue) - blk_run_queue_async(md->queue); + if (!q->mq_ops && run_queue) { + spin_lock_irqsave(q->queue_lock, flags); + blk_run_queue_async(q); + spin_unlock_irqrestore(q->queue_lock, flags); + } /* * dm_put() must be at the end of this function. See the comment above