nvme: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code (a6eaa884) · Commits · 戴 / test

Make nvme_requeue_req() check BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED. Remove the QUEUE_FLAG_STOPPED manipulations that became superfluous because of this change. Change blk_queue_stopped() tests into blk_mq_queue_stopped(). This patch fixes a race condition: using queue_flag_clear_unlocked() is not safe if any other function that manipulates the queue flags can be called concurrently, e.g. blk_cleanup_queue(). Signed-off-by:

Bart Van Assche <bart.vanassche@sandisk.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Sagi Grimberg <sagi@grimberg.me> Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Jens Axboe <axboe@fb.com>

drivers/nvme/host/core.c

+2 −14

Original line number	Diff line number	Diff line
		@@ -201,13 +201,7 @@ fail:

		void nvme_requeue_req(struct request *req)
		{
		unsigned long flags;

		blk_mq_requeue_request(req, false);
		spin_lock_irqsave(req->q->queue_lock, flags);
		if (!blk_queue_stopped(req->q))
		blk_mq_kick_requeue_list(req->q);
		spin_unlock_irqrestore(req->q->queue_lock, flags);
		blk_mq_requeue_request(req, !blk_mq_queue_stopped(req->q));
		}
		EXPORT_SYMBOL_GPL(nvme_requeue_req);

		@@ -2076,13 +2070,8 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
		struct nvme_ns *ns;

		mutex_lock(&ctrl->namespaces_mutex);
		list_for_each_entry(ns, &ctrl->namespaces, list) {
		spin_lock_irq(ns->queue->queue_lock);
		queue_flag_set(QUEUE_FLAG_STOPPED, ns->queue);
		spin_unlock_irq(ns->queue->queue_lock);

		list_for_each_entry(ns, &ctrl->namespaces, list)
		blk_mq_quiesce_queue(ns->queue);
		}
		mutex_unlock(&ctrl->namespaces_mutex);
		}
		EXPORT_SYMBOL_GPL(nvme_stop_queues);
		@@ -2093,7 +2082,6 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)

		mutex_lock(&ctrl->namespaces_mutex);
		list_for_each_entry(ns, &ctrl->namespaces, list) {
		queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, ns->queue);
		blk_mq_start_stopped_hw_queues(ns->queue, true);
		blk_mq_kick_requeue_list(ns->queue);
		}

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