Make sure that the tag_list_lock mutex is no longer held than necessary. This change reduces latency if e.g. blk_mq_quiesce_tagset() is called concurrently from more than one thread. This function is used by the NVMe core and also by the UFS driver.

Reported-by: Peter Wang peter.wang@mediatek.com Cc: Chao Leng lengchao@huawei.com Cc: Ming Lei ming.lei@redhat.com Cc: stable@vger.kernel.org Fixes: commit 414dd48e882c ("blk-mq: add tagset quiesce interface") Signed-off-by: Bart Van Assche bvanassche@acm.org --- block/blk-mq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c index 4b2c8e940f59..1ef227dfb9ba 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -283,8 +283,9 @@ void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set) if (!blk_queue_skip_tagset_quiesce(q)) blk_mq_quiesce_queue_nowait(q); } - blk_mq_wait_quiesce_done(set); mutex_unlock(&set->tag_list_lock); + + blk_mq_wait_quiesce_done(set); } EXPORT_SYMBOL_GPL(blk_mq_quiesce_tagset);