From f4560ffe8cec1361b1021d81aca6a4173f8e7c87 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sun, 18 Jun 2017 14:24:27 -0600 Subject: blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue It is required that no dispatch can happen any more once blk_mq_quiesce_queue() returns, and we don't have such requirement on APIs of stopping queue. But blk_mq_quiesce_queue() still may not block/drain dispatch in the the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical sections for fixing this issue. Also blk_mq_quiesce_queue() is implemented via stopping queue, which limits its uses, and easy to cause race, because any queue restart in other paths may break blk_mq_quiesce_queue(). With the introduced flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue for quiescing any more. Signed-off-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- include/linux/blk-mq.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/blk-mq.h') diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 787d8a2a2ac6..de6536c14ae7 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -268,6 +268,10 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues); */ static inline void blk_mq_quiesce_queue_nowait(struct request_queue *q) { + spin_lock_irq(q->queue_lock); + queue_flag_set(QUEUE_FLAG_QUIESCED, q); + spin_unlock_irq(q->queue_lock); + blk_mq_stop_hw_queues(q); } -- cgit