diff options
| author | Tejun Heo <tj@kernel.org> | 2014-08-16 08:02:24 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-08-21 20:37:51 -0500 |
| commit | cddd5d17642cc6881352732693c2ae6930e9ce65 (patch) | |
| tree | 5fad9444dbe5b3d2347d43c2bfe77383573b9031 | |
| parent | a68aafa5b297d99c2d0c38689089a752126e9e79 (diff) | |
| download | linux-cddd5d17642cc6881352732693c2ae6930e9ce65.tar.bz2 | |
blk-mq: blk_mq_freeze_queue() should allow nesting
While converting to percpu_ref for freezing, add703fda981 ("blk-mq:
use percpu_ref for mq usage count") incorrectly made
blk_mq_freeze_queue() misbehave when freezing is nested due to
percpu_ref_kill() being invoked on an already killed ref.
Fix it by making blk_mq_freeze_queue() kill and kick the queue only
for the outermost freeze attempt. All the nested ones can simply wait
for the ref to reach zero.
While at it, remove unnecessary @wake initialization from
blk_mq_unfreeze_queue().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | block/blk-mq.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index a0565bb20fd5..7950f8d7c1bb 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -112,18 +112,22 @@ static void blk_mq_usage_counter_release(struct percpu_ref *ref) */ void blk_mq_freeze_queue(struct request_queue *q) { + bool freeze; + spin_lock_irq(q->queue_lock); - q->mq_freeze_depth++; + freeze = !q->mq_freeze_depth++; spin_unlock_irq(q->queue_lock); - percpu_ref_kill(&q->mq_usage_counter); - blk_mq_run_queues(q, false); + if (freeze) { + percpu_ref_kill(&q->mq_usage_counter); + blk_mq_run_queues(q, false); + } wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter)); } static void blk_mq_unfreeze_queue(struct request_queue *q) { - bool wake = false; + bool wake; spin_lock_irq(q->queue_lock); wake = !--q->mq_freeze_depth; |