Commit 00e885ef authored by Chris Leech's avatar Chris Leech Committed by Jens Axboe
Browse files

blk-mq: fix "bad unlock balance detected" on q->srcu in __blk_mq_run_dispatch_ops 



The 'q' parameter of the macro __blk_mq_run_dispatch_ops may not be one
local variable, such as, it is rq->q, then request queue pointed by
this variable could be changed to another queue in case of
BLK_MQ_F_TAG_QUEUE_SHARED after 'dispatch_ops' returns, then
'bad unlock balance' is triggered.

Fixes the issue by adding one local variable for doing srcu lock/unlock.

Fixes: 2a904d00 ("blk-mq: remove hctx_lock and hctx_unlock")
Cc: Marco Patalano <mpatalan@redhat.com>
Signed-off-by: default avatarChris Leech <cleech@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230310010913.1014789-1-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9b0cb770

block/blk-mq.h

+3 −2
Original line number Diff line number Diff line
@@ -378,12 +378,13 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, 
#define __blk_mq_run_dispatch_ops(q, check_sleep, dispatch_ops)	\

do {								\

	if ((q)->tag_set->flags & BLK_MQ_F_BLOCKING) {		\

		struct blk_mq_tag_set *__tag_set = (q)->tag_set; \

		int srcu_idx;					\

								\

		might_sleep_if(check_sleep);			\

		srcu_idx = srcu_read_lock((q)->tag_set->srcu);	\

		srcu_idx = srcu_read_lock(__tag_set->srcu);	\

		(dispatch_ops);					\

		srcu_read_unlock((q)->tag_set->srcu, srcu_idx);	\

		srcu_read_unlock(__tag_set->srcu, srcu_idx);	\

	} else {						\

		rcu_read_lock();				\

		(dispatch_ops);					\