[PATCH v3 1/3] nvme: use blk_mq_start_hw_queues() in nvme_kill_queues()

[Ming Lei]

Inside nvme_kill_queues(), we have to start hw queues for
draining requests in sw queues, .dispatch list and requeue list,
so use blk_mq_start_hw_queues() instead of blk_mq_start_stopped_hw_queues()
which only run queues if queues are stopped, but the queues may have
been started already, for example nvme_start_queues() is called in reset work
function.

blk_mq_start_hw_queues() run hw queues in current context, instead
of running asynchronously like before. Given nvme_kill_queues() is
run from either remove context or reset worker context, both are fine
to run hw queue directly. And the mutex of namespaces_mutex isn't a
problem too becasue nvme_start_freeze() runs hw queue in this way
already.

Cc: stable at vger.kernel.org
Reported-by: Zhang Yi <yizhan at redhat.com>
Reviewed-by: Keith Busch <keith.busch at intel.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 drivers/nvme/host/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index d5e0906262ea..40d5e4a9e8d7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2437,7 +2437,13 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
 		revalidate_disk(ns->disk);
 		blk_set_queue_dying(ns->queue);
 		blk_mq_abort_requeue_list(ns->queue);
-		blk_mq_start_stopped_hw_queues(ns->queue, true);
+
+		/*
+		 * Forcibly start all queues to avoid having stuck requests.
+		 * Note that we must ensure the queues are not stopped
+		 * when the final removal happens.
+		 */
+		blk_mq_start_hw_queues(ns->queue);
 	}
 	mutex_unlock(&ctrl->namespaces_mutex);
 }
-- 
2.9.4