From: Sagi Grimberg <sagi@grimberg.me>
Date: Thu, 21 Dec 2017 14:54:15 +0200
Subject: nvme-rdma: fix concurrent reset and reconnect
Patch-mainline: v4.15-rc8
Git-commit: d5bf4b7f437c250821d40c3e32158729e6b484ce
References: FATE#323952, FATE#322506

Now ctrl state machine allows to transition from RESETTING to
RECONNECTING.  In nvme-rdma when we receive a rdma cm DISONNECTED event,
we trigger nvme_rdma_error_recovery. This happens also when we execute a
controller reset, issue a cm diconnect request and receive a cm
disconnect reply, as a result, the reset work and the error recovery work
can run concurrently.

Until now the state machine prevented from the error recovery work from
running as a result of a controller reset (RESETTING -> RECONNECTING was
not allowed).

To fix this, we adopt the FC state machine approach, we always transition
from LIVE to RESETTING and only then to RECONNECTING.  We do this both
for the error recovery work and the controller reset work:

 1. transition to RESETTING
 2. teardown the controller association
 3. transition to RECONNECTING

This will restore the protection against reset work and error recovery work
from concurrently running together.

Fixes: 3cec7f9de448 ("nvme: allow controller RESETTING to RECONNECTING transition")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/nvme/host/rdma.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -974,12 +974,18 @@ static void nvme_rdma_error_recovery_wor
 	blk_mq_unquiesce_queue(ctrl->ctrl.admin_q);
 	nvme_start_queues(&ctrl->ctrl);
 
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RECONNECTING)) {
+		/* state change failure should never happen */
+		WARN_ON_ONCE(1);
+		return;
+	}
+
 	nvme_rdma_reconnect_or_remove(ctrl);
 }
 
 static void nvme_rdma_error_recovery(struct nvme_rdma_ctrl *ctrl)
 {
-	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RECONNECTING))
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RESETTING))
 		return;
 
 	queue_work(nvme_wq, &ctrl->err_work);
@@ -1753,6 +1759,12 @@ static void nvme_rdma_reset_ctrl_work(st
 	nvme_stop_ctrl(&ctrl->ctrl);
 	nvme_rdma_shutdown_ctrl(ctrl, false);
 
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RECONNECTING)) {
+		/* state change failure should never happen */
+		WARN_ON_ONCE(1);
+		return;
+	}
+
 	ret = nvme_rdma_configure_admin_queue(ctrl, false);
 	if (ret)
 		goto out_fail;