nvme: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code

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>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 75565b5951d92afbacd58e814f72edea4da9c514..ef34f2f3566ae6b536b4d5ba4e7bbecbe68c1ddd 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -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);
        }