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. 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.vanass...@sandisk.com>
Cc: Keith Busch <keith.bu...@intel.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Sagi Grimberg <s...@grimberg.me>
---
 drivers/nvme/host/core.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e4a6f2d..18a265d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -205,7 +205,7 @@ void nvme_requeue_req(struct request *req)
 
        blk_mq_requeue_request(req, false);
        spin_lock_irqsave(req->q->queue_lock, flags);
-       if (!blk_queue_stopped(req->q))
+       if (!blk_mq_queue_stopped(req->q))
                blk_mq_kick_requeue_list(req->q);
        spin_unlock_irqrestore(req->q->queue_lock, flags);
 }
@@ -2077,10 +2077,6 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
 
        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);
-
                blk_mq_cancel_requeue_work(ns->queue);
                blk_mq_stop_hw_queues(ns->queue);
        }
@@ -2094,7 +2090,6 @@ 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);
        }
-- 
2.10.1

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