linux-kernel - [PATCH v3 3/3] nvme: handle connectivity loss in nvme_set_queue

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Message-Id: <20241129-nvme-fc-handle-com-lost-v3-3-d8967b3cae54@kernel.org>
Date: Fri, 29 Nov 2024 10:28:25 +0100
From: Daniel Wagner <wagi@...nel.org>
To: James Smart <james.smart@...adcom.com>, Keith Busch <kbusch@...nel.org>, 
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>, 
 Hannes Reinecke <hare@...e.de>, Paul Ely <paul.ely@...adcom.com>
Cc: linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Daniel Wagner <wagi@...nel.org>
Subject: [PATCH v3 3/3] nvme: handle connectivity loss in
 nvme_set_queue_count

When the set feature attempts fails with any NVME status code set in
nvme_set_queue_count, the function still report success. Though the
numbers of queues set to 0. This is done to support controllers in
degraded state (the admin queue is still up and running but no IO
queues).

Though there is an exception. When nvme_set_features reports an host
path error, nvme_set_queue_count should propagate this error as the
connectivity is lost, which means also the admin queue is not working
anymore.

Fixes: 9a0be7abb62f ("nvme: refactor set_queue_count")
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Daniel Wagner <wagi@...nel.org>
---
 drivers/nvme/host/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2a07c2c540b26c8cbe886711abaf6f0afbe6c4df..aa2a7c7d4d0ae7bd1f7fb704e55c0a8d724b9d56 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1677,7 +1677,12 @@ int nvme_set_queue_count(struct nvme_ctrl *ctrl, int *count)
 
 	status = nvme_set_features(ctrl, NVME_FEAT_NUM_QUEUES, q_count, NULL, 0,
 			&result);
-	if (status < 0)
+	/*
+	 * It's either a kernel error or the host observed a connection
+	 * lost. In either case it's not possible communicate with the
+	 * controller and thus enter the error code path.
+	 */
+	if (status < 0 || status == NVME_SC_HOST_PATH_ERROR)
 		return status;
 
 	/*

-- 
2.47.0