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 <jinpu.wang@profitbricks.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 4ea4dd8..fe822aa 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -380,15 +380,13 @@
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 @@
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 @@
}
if (ret)
- blk_mq_unregister_disk(disk);
+ __blk_mq_unregister_disk(disk);
else
q->mq_sysfs_init_done = true;
out: