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dm rq: don't call blk_mq_queue_stopped() in dm_stop_queue()

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[ Upstream commit e766668c6cd49d741cfb49eaeb38998ba34d27bc ]

dm_stop_queue() only uses blk_mq_quiesce_queue() so it doesn't
formally stop the blk-mq queue; therefore there is no point making the
blk_mq_queue_stopped() check -- it will never be stopped.

In addition, even though dm_stop_queue() actually tries to quiesce hw
queues via blk_mq_quiesce_queue(), checking with blk_queue_quiesced()
to avoid unnecessary queue quiesce isn't reliable because: the
QUEUE_FLAG_QUIESCED flag is set before synchronize_rcu() and
dm_stop_queue() may be called when synchronize_rcu() from another
blk_mq_quiesce_queue() is in-progress.

Fixes: 7b17c2f7292ba ("dm: Fix a race condition related to stopping and starting queues")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ming Lei 2020-06-19 16:42:14 +08:00 committed by Greg Kroah-Hartman
parent 386f82040c
commit 0e0a146f97
1 changed files with 0 additions and 3 deletions
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3
drivers/md/dm-rq.c
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@ -70,9 +70,6 @@ void dm_start_queue(struct request_queue *q)
void dm_stop_queue(struct request_queue *q)
{
if (blk_mq_queue_stopped(q))
return;
blk_mq_quiesce_queue(q);
}