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Commit c0f3fd2b authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: fix deadlock in blk_mq_register_disk() error path 



If we fail registering any of the hardware queues, we call
into blk_mq_unregister_disk() with the hotplug mutex already
held. Since blk_mq_unregister_disk() attempts to acquire the
same mutex, we end up in a less than happy place.

Reported-by: default avatarJinpu Wang <jinpu.wang@profitbricks.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 6d25ec14

block/blk-mq-sysfs.c

+8 −4
Original line number Diff line number Diff line
@@ -380,15 +380,13 @@ static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx) 
	return ret;

}



void blk_mq_unregister_disk(struct gendisk *disk)

static void __blk_mq_unregister_disk(struct gendisk *disk)

{

	struct request_queue *q = disk->queue;

	struct blk_mq_hw_ctx *hctx;

	struct blk_mq_ctx *ctx;

	int i, j;



	blk_mq_disable_hotplug();



	queue_for_each_hw_ctx(q, hctx, i) {

		blk_mq_unregister_hctx(hctx);
@@ -405,6 +403,12 @@ void blk_mq_unregister_disk(struct gendisk *disk) 
	kobject_put(&disk_to_dev(disk)->kobj);



	q->mq_sysfs_init_done = false;

}



void blk_mq_unregister_disk(struct gendisk *disk)

{

	blk_mq_disable_hotplug();

	__blk_mq_unregister_disk(disk);

	blk_mq_enable_hotplug();

}
@@ -450,7 +454,7 @@ int blk_mq_register_disk(struct gendisk *disk) 
	}



	if (ret)

		blk_mq_unregister_disk(disk);

		__blk_mq_unregister_disk(disk);

	else

		q->mq_sysfs_init_done = true;

out: