From a23b2d6dc53613a8360c4e466b0a7381376b14d5 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Fri, 11 Nov 2016 17:05:27 -0800 Subject: [PATCH] dm rq: fix a race condition in rq_completed() 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 [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings --- drivers/md/dm.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 35caa4c17c3d..d043e50ebea7 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -868,6 +868,9 @@ static void end_clone_bio(struct bio *clone, int error) */ static void rq_completed(struct mapped_device *md, int rw, int run_queue) { + struct request_queue *q = md->queue; + unsigned long flags; + atomic_dec(&md->pending[rw]); /* nudge anyone waiting on suspend queue */ @@ -880,8 +883,11 @@ static void rq_completed(struct mapped_device *md, int rw, int run_queue) * back into ->request_fn() could deadlock attempting to grab the * queue lock again. */ - if (run_queue) - blk_run_queue_async(md->queue); + if (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