Queue can be started by other blk-mq APIs and can be used in different cases, this limits uses of blk_mq_quiesce_queue() if it is based on stopping queue, and make its usage very difficult, especially users have to use the stop queue APIs carefully for avoiding to break blk_mq_quiesce_queue().
We have applied the QUIESCED flag for draining and blocking dispatch, so it isn't necessary to stop queue any more. After stopping queue is removed, blk_mq_quiesce_queue() can be used safely and easily, then users won't worry about queue restarting during quiescing at all. Signed-off-by: Ming Lei <[email protected]> --- block/blk-mq.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 032045841856..84cce67caee3 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -168,8 +168,6 @@ void blk_mq_quiesce_queue(struct request_queue *q) unsigned int i; bool rcu = false; - __blk_mq_stop_hw_queues(q, true); - spin_lock_irq(q->queue_lock); queue_flag_set(QUEUE_FLAG_QUIESCED, q); spin_unlock_irq(q->queue_lock); @@ -198,7 +196,12 @@ void blk_mq_unquiesce_queue(struct request_queue *q) queue_flag_clear(QUEUE_FLAG_QUIESCED, q); spin_unlock_irq(q->queue_lock); - blk_mq_start_stopped_hw_queues(q, true); + /* + * During quiescing, requests can be inserted + * to scheduler's queue or sw queue, so we run + * queues for dispatching these requests. + */ + blk_mq_start_hw_queues(q); } EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue); -- 2.9.4
