From: Sagi Grimberg <sagi@grimberg.me>
Date: Fri, 24 Jul 2020 15:10:12 -0700
Subject: [PATCH] nvme-tcp: fix controller reset hang during traffic
Patch-mainline: v5.9-rc1
Git-commit: 2875b0aecabe2f081a8432e2bc85b85df0529490
References: bsc#1181161

commit fe35ec58f0d3 ("block: update hctx map when use multiple maps")
exposed an issue where we may hang trying to wait for queue freeze
during I/O. We call blk_mq_update_nr_hw_queues which in case of multiple
queue maps (which we have now for default/read/poll) is attempting to
freeze the queue. However we never started queue freeze when starting the
reset, which means that we have inflight pending requests that entered the
queue that we will not complete once the queue is quiesced.

So start a freeze before we quiesce the queue, and unfreeze the queue
after we successfully connected the I/O queues (and make sure to call
blk_mq_update_nr_hw_queues only after we are sure that the queue was
already frozen).

This follows to how the pci driver handles resets.

Fixes: fe35ec58f0d3 ("block: update hctx map when use multiple maps")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 drivers/nvme/host/tcp.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1608,15 +1608,20 @@ static int nvme_tcp_configure_io_queues(
 				goto out_free_tag_set;
 			}
 		}
-	} else {
-		blk_mq_update_nr_hw_queues(ctrl->tagset,
-			ctrl->queue_count - 1);
 	}
 
 	ret = nvme_tcp_start_io_queues(ctrl);
 	if (ret)
 		goto out_cleanup_connect_q;
 
+	if (!new) {
+		nvme_start_queues(ctrl);
+		nvme_wait_freeze(ctrl);
+		blk_mq_update_nr_hw_queues(ctrl->tagset,
+			ctrl->queue_count - 1);
+		nvme_unfreeze(ctrl);
+	}
+
 	return 0;
 
 out_cleanup_connect_q:
@@ -1731,6 +1736,7 @@ static void nvme_tcp_teardown_io_queues(
 {
 	if (ctrl->queue_count <= 1)
 		return;
+	nvme_start_freeze(ctrl);
 	nvme_stop_queues(ctrl);
 	nvme_tcp_stop_io_queues(ctrl);
 	if (ctrl->tagset) {