Commit 49e4d04f authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: Drop spurious might_sleep() from blk_put_queue() 



Dan reports the following smatch detected the following:

  block/blk-cgroup.c:1863 blkcg_schedule_throttle() warn: sleeping in atomic context

caused by blkcg_schedule_throttle() calling blk_put_queue() in an
non-sleepable context.

blk_put_queue() acquired might_sleep() in 63f93fd6 ("block: mark
blk_put_queue as potentially blocking") which transferred the might_sleep()
from blk_free_queue().

blk_free_queue() acquired might_sleep() in e8c7d14a ("block: revert back
to synchronous request_queue removal") while turning request_queue removal
synchronous. However, this isn't necessary as nothing in the free path
actually requires sleeping.

It's pretty unusual to require a sleeping context in a put operation and
it's not needed in the first place. Let's drop it.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarDan Carpenter <error27@gmail.com>
Link: https://lkml.kernel.org/r/Y7g3L6fntnTtOm63@kili


Cc: Christoph Hellwig <hch@lst.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Fixes: e8c7d14a ("block: revert back to synchronous request_queue removal") # v5.9+
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/Y7iFwjN+XzWvLv3y@slm.duckdns.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b2b50d57

block/blk-core.c

+0 −3
Original line number Diff line number Diff line
@@ -283,12 +283,9 @@ static void blk_free_queue(struct request_queue *q) 
 *

 * Decrements the refcount of the request_queue and free it when the refcount

 * reaches 0.

 *

 * Context: Can sleep.

 */

void blk_put_queue(struct request_queue *q)

{

	might_sleep();

	if (refcount_dec_and_test(&q->refs))

		blk_free_queue(q);

}