blk-mq: avoid sleep in blk_mq_alloc_request_hctx
authorKemeng Shi <shikemeng@huaweicloud.com>
Wed, 18 Jan 2023 09:37:13 +0000 (17:37 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 10 Mar 2023 08:32:43 +0000 (09:32 +0100)
commit14cea6cc8ad3c031394da8c7c1468555fe9ee47e
treeb53f47ad6282abf4f0c3ffc9d0dcbd47ed25e6b2
parent76e64c9a0a8220957b81a741de0a1c85e0e85494
blk-mq: avoid sleep in blk_mq_alloc_request_hctx

[ Upstream commit 6ee858a3d3270a68902d66bb47c151a83622535c ]

Commit 1f5bd336b9150 ("blk-mq: add blk_mq_alloc_request_hctx") add
blk_mq_alloc_request_hctx to send commands to a specific queue. If
BLK_MQ_REQ_NOWAIT is not set in tag allocation, we may change to different
hctx after sleep and get tag from unexpected hctx. So BLK_MQ_REQ_NOWAIT
must be set in flags for blk_mq_alloc_request_hctx.
After commit 600c3b0cea784 ("blk-mq: open code __blk_mq_alloc_request in
blk_mq_alloc_request_hctx"), blk_mq_alloc_request_hctx return -EINVAL
if both BLK_MQ_REQ_NOWAIT and BLK_MQ_REQ_RESERVED are not set instead of
if BLK_MQ_REQ_NOWAIT is not set. So if BLK_MQ_REQ_NOWAIT is not set and
BLK_MQ_REQ_RESERVED is set, blk_mq_alloc_request_hctx could alloc tag
from unexpected hctx. I guess what we need here is that return -EINVAL
if either BLK_MQ_REQ_NOWAIT or BLK_MQ_REQ_RESERVED is not set.

Currently both BLK_MQ_REQ_NOWAIT and BLK_MQ_REQ_RESERVED will be set if
specific hctx is needed in nvme_auth_submit, nvmf_connect_io_queue
and nvmf_connect_admin_queue. Fix the potential BLK_MQ_REQ_NOWAIT missed
case in future.

Fixes: 600c3b0cea78 ("blk-mq: open code __blk_mq_alloc_request in blk_mq_alloc_request_hctx")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
block/blk-mq.c