linux-kernel - [PATCH 5.12 042/173] nvmet: fix false keep-alive timeout when a controller is torn down

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Message-Id: <20210614102659.567114639@linuxfoundation.org>
Date:   Mon, 14 Jun 2021 12:26:14 +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, Yi Zhang <yi.zhang@...hat.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Chaitanya Kulkarni <chaitanya.kulkarni@....com>,
        Hannes Reinecke <hare@...e.de>, Christoph Hellwig <hch@....de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 042/173] nvmet: fix false keep-alive timeout when a controller is torn down

From: Sagi Grimberg <sagi@...mberg.me>

[ Upstream commit aaeadd7075dc9e184bc7876e9dd7b3bada771df2 ]

Controller teardown flow may take some time in case it has many I/O
queues, and the host may not send us keep-alive during this period.
Hence reset the traffic based keep-alive timer so we don't trigger
a controller teardown as a result of a keep-alive expiration.

Reported-by: Yi Zhang <yi.zhang@...hat.com>
Signed-off-by: Sagi Grimberg <sagi@...mberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@....com>
Reviewed-by: Hannes Reinecke <hare@...e.de>
Tested-by: Yi Zhang <yi.zhang@...hat.com>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvme/target/core.c  | 15 +++++++++++----
 drivers/nvme/target/nvmet.h |  2 +-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 7d16cb4cd8ac..83921dab8368 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -388,10 +388,10 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 {
 	struct nvmet_ctrl *ctrl = container_of(to_delayed_work(work),
 			struct nvmet_ctrl, ka_work);
-	bool cmd_seen = ctrl->cmd_seen;
+	bool reset_tbkas = ctrl->reset_tbkas;
 
-	ctrl->cmd_seen = false;
-	if (cmd_seen) {
+	ctrl->reset_tbkas = false;
+	if (reset_tbkas) {
 		pr_debug("ctrl %d reschedule traffic based keep-alive timer\n",
 			ctrl->cntlid);
 		schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
@@ -804,6 +804,13 @@ void nvmet_sq_destroy(struct nvmet_sq *sq)
 	percpu_ref_exit(&sq->ref);
 
 	if (ctrl) {
+		/*
+		 * The teardown flow may take some time, and the host may not
+		 * send us keep-alive during this period, hence reset the
+		 * traffic based keep-alive timer so we don't trigger a
+		 * controller teardown as a result of a keep-alive expiration.
+		 */
+		ctrl->reset_tbkas = true;
 		nvmet_ctrl_put(ctrl);
 		sq->ctrl = NULL; /* allows reusing the queue later */
 	}
@@ -953,7 +960,7 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 	}
 
 	if (sq->ctrl)
-		sq->ctrl->cmd_seen = true;
+		sq->ctrl->reset_tbkas = true;
 
 	return true;
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 5aad34b106dc..43a668dc8bc4 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -166,7 +166,7 @@ struct nvmet_ctrl {
 	struct nvmet_subsys	*subsys;
 	struct nvmet_sq		**sqs;
 
-	bool			cmd_seen;
+	bool			reset_tbkas;
 
 	struct mutex		lock;
 	u64			cap;
-- 
2.30.2