Commit 08c875cb authored Jul 28, 2020 by Daniel Wagner Committed by Jens Axboe Jul 28, 2020

block: Use non _rcu version of list functions for tag_set_list



tag_set_list is only accessed under the tag_set_lock lock. There is
no need for using the _rcu list functions.

The _rcu list function were introduced to allow read access to the
tag_set_list protected under RCU, see 705cda97 ("blk-mq: Make it
safe to use RCU to iterate over blk_mq_tag_set.tag_list") and
05b79413 ("Revert "blk-mq: don't handle TAG_SHARED in restart"").
Those changes got reverted later but the cleanup commit missed a
couple of places to undo the changes.

Fixes: 97889f9a ("blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()"
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent ef45fe47

block/blk-mq.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2899,7 +2899,7 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
		struct blk_mq_tag_set *set = q->tag_set;

		mutex_lock(&set->tag_list_lock);
		list_del_rcu(&q->tag_set_list);
		list_del(&q->tag_set_list);
		if (list_is_singular(&set->tag_list)) {
		/* just transitioned to unshared */
		set->flags &= ~BLK_MQ_F_TAG_SHARED;
		@@ -2926,7 +2926,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
		}
		if (set->flags & BLK_MQ_F_TAG_SHARED)
		queue_set_hctx_shared(q, true);
		list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
		list_add_tail(&q->tag_set_list, &set->tag_list);

		mutex_unlock(&set->tag_list_lock);
		}

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