linux-kernel - [PATCH] nvme: update keep alive interval when kato is modified

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Message-ID: <b7cde4c23c44485198f12739bb8fbca0@kioxia.com>
Date:   Mon, 2 Aug 2021 00:24:37 +0000
From:   sasaki tatsuya <tatsuya6.sasaki@...xia.com>
To:     "kbusch@...nel.org" <kbusch@...nel.org>,
        "axboe@...com" <axboe@...com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] nvme: update keep alive interval when kato is modified

Currently the connection between host and NVMe-oF target gets
disconnected by keep-alive timeout when a user connects to a target
with a relatively large kato value and then sets the smaller kato
with a set features command (e.g. connects with 60 seconds kato value
and then sets 10 seconds kato value).

The cause is that keep alive command interval on the host, which is
defined as unsigned int kato in nvme_ctrl structure, does not follow
the kato value changes.

This patch updates the keep alive interval in the following steps when
the kato is modified by a set features command: stops the keep alive
work queue, then sets the kato as new timer value and re-start the queue.

Signed-off-by: Tatsuya Sasaki <tatsuya6.sasaki@...xia.com>
---
 drivers/nvme/host/core.c  |  3 ++-
 drivers/nvme/host/ioctl.c | 17 +++++++++++++++++
 drivers/nvme/host/nvme.h  |  1 +
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 66973bb56..3e821a0be 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1242,13 +1242,14 @@ static void nvme_keep_alive_work(struct work_struct *work)
 	blk_execute_rq_nowait(NULL, rq, 0, nvme_keep_alive_end_io);
 }
 
-static void nvme_start_keep_alive(struct nvme_ctrl *ctrl)
+void nvme_start_keep_alive(struct nvme_ctrl *ctrl)
 {
 	if (unlikely(ctrl->kato == 0))
 		return;
 
 	nvme_queue_keep_alive_work(ctrl);
 }
+EXPORT_SYMBOL_GPL(nvme_start_keep_alive);
 
 void nvme_stop_keep_alive(struct nvme_ctrl *ctrl)
 {
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 9557ead02..574f956f0 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -225,6 +225,23 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			return -EFAULT;
 	}
 
+	/*
+	 * Keep alive commands interval on the host should be updated
+	 * when KATO is modified by Set Features commands.
+	 */
+	if (!status && c.common.opcode == nvme_admin_set_features &&
+	    ((u8)c.common.cdw10 & 0xFF) == NVME_FEAT_KATO) {
+		/* ms -> s */
+		unsigned int new_kato = DIV_ROUND_UP(c.common.cdw11, 1000);
+
+		dev_info(ctrl->device,
+			 "keep alive commands interval on the host is updated from %u milliseconds to %u milliseconds\n",
+			 ctrl->kato * 1000 / 2, new_kato * 1000 / 2);
+		nvme_stop_keep_alive(ctrl);
+		ctrl->kato = new_kato;
+		nvme_start_keep_alive(ctrl);
+	}
+
 	return status;
 }
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 0015860ec..150ad6d4d 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -666,6 +666,7 @@ int nvme_get_features(struct nvme_ctrl *dev, unsigned int fid,
 		      unsigned int dword11, void *buffer, size_t buflen,
 		      u32 *result);
 int nvme_set_queue_count(struct nvme_ctrl *ctrl, int *count);
+void nvme_start_keep_alive(struct nvme_ctrl *ctrl);
 void nvme_stop_keep_alive(struct nvme_ctrl *ctrl);
 int nvme_reset_ctrl(struct nvme_ctrl *ctrl);
 int nvme_reset_ctrl_sync(struct nvme_ctrl *ctrl);
-- 
2.25.1