linux-kernel - [PATCH 5.8 088/177] nvme-tcp: fix reset hang if controller died in the middle of a reset

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Message-Id: <20200915140657.860619665@linuxfoundation.org>
Date:   Tue, 15 Sep 2020 16:12:39 +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, Sagi Grimberg <sagi@...mberg.me>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 088/177] nvme-tcp: fix reset hang if controller died in the middle of a reset

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

[ Upstream commit e5c01f4f7f623e768e868bcc08d8e7ceb03b75d0 ]

If the controller becomes unresponsive in the middle of a reset, we will
hang because we are waiting for the freeze to complete, but that cannot
happen since we have commands that are inflight holding the
q_usage_counter, and we can't blindly fail requests that times out.

So give a timeout and if we cannot wait for queue freeze before
unfreezing, fail and have the error handling take care how to proceed
(either schedule a reconnect of remove the controller).

Signed-off-by: Sagi Grimberg <sagi@...mberg.me>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvme/host/tcp.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 65a3bad778104..f1f66bf96cbb9 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1753,7 +1753,15 @@ static int nvme_tcp_configure_io_queues(struct nvme_ctrl *ctrl, bool new)
 
 	if (!new) {
 		nvme_start_queues(ctrl);
-		nvme_wait_freeze(ctrl);
+		if (!nvme_wait_freeze_timeout(ctrl, NVME_IO_TIMEOUT)) {
+			/*
+			 * If we timed out waiting for freeze we are likely to
+			 * be stuck.  Fail the controller initialization just
+			 * to be safe.
+			 */
+			ret = -ENODEV;
+			goto out_wait_freeze_timed_out;
+		}
 		blk_mq_update_nr_hw_queues(ctrl->tagset,
 			ctrl->queue_count - 1);
 		nvme_unfreeze(ctrl);
@@ -1761,6 +1769,9 @@ static int nvme_tcp_configure_io_queues(struct nvme_ctrl *ctrl, bool new)
 
 	return 0;
 
+out_wait_freeze_timed_out:
+	nvme_stop_queues(ctrl);
+	nvme_tcp_stop_io_queues(ctrl);
 out_cleanup_connect_q:
 	if (new)
 		blk_cleanup_queue(ctrl->connect_q);
-- 
2.25.1