From: Christoph Hellwig <hch@lst.de>
Date: Wed, 3 Mar 2021 13:51:47 +0100
Subject: nvme: allocate the keep alive request using BLK_MQ_REQ_NOWAIT
Patch-mainline: v5.12-rc4
Git-commit: 985c5a329dfe5ecb782551cddef48912961b83f1
References: bsc#1182077

To avoid an error recovery deadlock where the keep alive work is waiting
for a request and thus can't be flushed to make progress for tearing down
the controller.  Also print the error code returned from
blk_mq_alloc_request to help debugging any future issues in this code.

Based on an earlier patch from Hannes Reinecke <hare@suse.de>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/nvme/host/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -985,11 +985,11 @@ static void nvme_keep_alive_work(struct
 	}
 
 	rq = nvme_alloc_request(ctrl->admin_q, &ctrl->ka_cmd,
-				BLK_MQ_REQ_RESERVED,
+				BLK_MQ_REQ_RESERVED | BLK_MQ_REQ_NOWAIT,
 				NVME_QID_ANY);
 	if (IS_ERR(rq)) {
 		/* allocation failure, reset the controller */
-		dev_err(ctrl->device, "keep-alive failed\n");
+		dev_err(ctrl->device, "keep-alive failed: %ld\n", PTR_ERR(rq));
 		nvme_reset_ctrl(ctrl);
 		return;
 	}