diff options
| author | Akinobu Mita <akinobu.mita@gmail.com> | 2015-09-27 02:09:22 +0900 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-09-29 11:32:48 -0600 |
| commit | 0e6263682014d480b8d7b8c10287f4536066b54f (patch) | |
| tree | 6ebd842a4a9ef717cfc4a05c99fddede9fb4328e | |
| parent | a723bab3d7529133f71fc8a5e96f86e3639a0d13 (diff) | |
blk-mq: fix q->mq_usage_counter access race
CPU hotplug handling for blk-mq (blk_mq_queue_reinit) accesses
q->mq_usage_counter while freezing all request queues in all_q_list.
On the other hand, q->mq_usage_counter is deinitialized in
blk_mq_free_queue() before deleting the queue from all_q_list.
So if CPU hotplug event occurs in the window, percpu_ref_kill() is
called with q->mq_usage_counter which has already been marked dead,
and it triggers warning. Fix it by deleting the queue from all_q_list
earlier than destroying q->mq_usage_counter.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | block/blk-mq.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 92648d8d6a4a..3a39184e82e5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2067,15 +2067,16 @@ void blk_mq_free_queue(struct request_queue *q) { struct blk_mq_tag_set *set = q->tag_set; + mutex_lock(&all_q_mutex); + list_del_init(&q->all_q_node); + mutex_unlock(&all_q_mutex); + blk_mq_del_queue_tag_set(q); blk_mq_exit_hw_queues(q, set, set->nr_hw_queues); blk_mq_free_hw_queues(q, set); percpu_ref_exit(&q->mq_usage_counter); - mutex_lock(&all_q_mutex); - list_del_init(&q->all_q_node); - mutex_unlock(&all_q_mutex); } /* Basically redo blk_mq_init_queue with queue frozen */ |