From c0f3fd2b387448d67ae83c4ce1cc69da375b9186 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 2 Aug 2016 08:45:44 -0600 Subject: 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: Jinpu Wang Signed-off-by: Jens Axboe --- block/blk-mq-sysfs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index 4ea4dd8a1eed..fe822aa5b8e4 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -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: -- cgit