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[2403:580b:97e8:0:82ce:f179:8a79:69f4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7722a4bf378sm12085276b3a.60.2025.09.01.20.52.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Sep 2025 20:52:19 -0700 (PDT) From: alistair23@gmail.com X-Google-Original-From: alistair.francis@wdc.com To: kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, linux-nvme@lists.infradead.org Cc: linux-kernel@vger.kernel.org, alistair23@gmail.com, Alistair Francis Subject: [PATCH] nvme: Use non zero KATO for persistent discovery connections Date: Tue, 2 Sep 2025 13:52:11 +1000 Message-ID: <20250902035211.2953174-1-alistair.francis@wdc.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Alistair Francis 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 Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke --- drivers/nvme/host/core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 812c1565114f..bb9685b67338 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4986,8 +4986,14 @@ 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 =3D NVME_DEFAULT_KATO; + nvme_start_keep_alive(ctrl); + } nvme_change_uevent(ctrl, "NVME_EVENT=3Drediscover"); + } =20 if (ctrl->queue_count > 1) { nvme_queue_scan(ctrl); --=20 2.50.1