From: Alistair Francis <alistair.francis@wdc.com>
Date: Tue, 2 Sep 2025 03:52:11 +0000 (+1000)
Subject: nvme: Use non zero KATO for persistent discovery connections
X-Git-Tag: v6.12.58~408
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a8576f1e80d99c9aa7abad0e28ad8c51f4fe6362;p=thirdparty%2Fkernel%2Fstable.git

nvme: Use non zero KATO for persistent discovery connections

[ Upstream commit 2e482655019ab6fcfe8865b62432c6d03f0b5f80 ]

The NVMe Base Specification 2.1 states that:

"""
A host requests an explicit persistent connection ... by specifying a
non-zero Keep Alive Timer value in the Connect command.
"""

As such if we are starting a persistent connection to a discovery
controller and the KATO is currently 0 we need to update KATO to a non
zero value to avoid continuous timeouts on the target.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 24d82d35041b5..a3b9f8ea235f7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4740,8 +4740,14 @@ void nvme_start_ctrl(struct nvme_ctrl *ctrl)
 	 * checking that they started once before, hence are reconnecting back.
 	 */
 	if (test_bit(NVME_CTRL_STARTED_ONCE, &ctrl->flags) &&
-	    nvme_discovery_ctrl(ctrl))
+	    nvme_discovery_ctrl(ctrl)) {
+		if (!ctrl->kato) {
+			nvme_stop_keep_alive(ctrl);
+			ctrl->kato = NVME_DEFAULT_KATO;
+			nvme_start_keep_alive(ctrl);
+		}
 		nvme_change_uevent(ctrl, "NVME_EVENT=rediscover");
+	}
 
 	if (ctrl->queue_count > 1) {
 		nvme_queue_scan(ctrl);