On Mon, 2017-06-05 at 23:59 +0800, Ming Lei wrote: > 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. Hello Ming, Since this patch depends on patch 1 I will wait with reviewing this patch until there is agreement about patch 1 in this series. Bart.
