blk-mq-debugfs: add missing debugfs_mutex in blk_mq_debugfs_register_hctxs()

hailan94 · Sasha Levin · commit 648aa7ce0bd8 · 2026-03-04T07:20:35.000-05:00
[ Upstream commit 9d20fd6 ] In blk_mq_update_nr_hw_queues(), debugfs_mutex is not held while creating debugfs entries for hctxs. Hence add debugfs_mutex there, it's safe because queue is not frozen. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
@@ -730,8 +730,10 @@ void blk_mq_debugfs_register_hctxs(struct request_queue *q)
 	struct blk_mq_hw_ctx *hctx;
 	unsigned long i;
 
+	mutex_lock(&q->debugfs_mutex);
 	queue_for_each_hw_ctx(q, hctx, i)
 		blk_mq_debugfs_register_hctx(q, hctx);
+	mutex_unlock(&q->debugfs_mutex);
 }
 
 void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)

Original file line number	Diff line number	Diff line change
`@@ -730,8 +730,10 @@ void blk_mq_debugfs_register_hctxs(struct request_queue *q)`
`730`	`730`	`struct blk_mq_hw_ctx *hctx;`
`731`	`731`	`unsigned long i;`
`732`	`732`
	`733`	`+ mutex_lock(&q->debugfs_mutex);`
`733`	`734`	`queue_for_each_hw_ctx(q, hctx, i)`
`734`	`735`	`blk_mq_debugfs_register_hctx(q, hctx);`
	`736`	`+ mutex_unlock(&q->debugfs_mutex);`
`735`	`737`	`}`
`736`	`738`
`737`	`739`	`void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)`