linux-kernel - [PATCH 4.9 51/94] nvme: use blk_mq_start_hw_queues() in nvme_kill

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Message-Id: <20170605153105.308674452@linuxfoundation.org>
Date:   Mon,  5 Jun 2017 18:17:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhang Yi <yizhan@...hat.com>,
        Keith Busch <keith.busch@...el.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Ming Lei <ming.lei@...hat.com>, Christoph Hellwig <hch@....de>
Subject: [PATCH 4.9 51/94] nvme: use blk_mq_start_hw_queues() in nvme_kill_queues()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ming Lei <ming.lei@...hat.com>

commit 806f026f9b901eaf1a6baeb48b5da18d6a4f818e upstream.

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.

Reported-by: Zhang Yi <yizhan@...hat.com>
Reviewed-by: Keith Busch <keith.busch@...el.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/nvme/host/core.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2049,7 +2049,13 @@ void nvme_kill_queues(struct nvme_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);
 }