[PATCH 2/2] nvmet-tcp: avoid circular locking dependency on install_queue()

[Hannes Reinecke]

nvmet_tcp_install_queue() is driven from the ->io_work workqueue
function, but will call flush_workqueue() which might trigger
->release_work() which in itself calls flush_work on ->io_work.

To avoid that check for pending queue in disconnecting status,
and return 'controller busy' until all disconnects are completed.

Signed-off-by: Hannes Reinecke <hare at suse.de>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>
---
 drivers/nvme/target/tcp.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index b3c1cc6690f6..850e40eb70a0 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -2121,8 +2121,17 @@ static u16 nvmet_tcp_install_queue(struct nvmet_sq *sq)
 		container_of(sq, struct nvmet_tcp_queue, nvme_sq);
 
 	if (sq->qid == 0) {
-		/* Let inflight controller teardown complete */
-		flush_workqueue(nvmet_wq);
+		struct nvmet_tcp_queue *q;
+
+		mutex_lock(&nvmet_tcp_queue_mutex);
+		list_for_each_entry(q, &nvmet_tcp_queue_list, queue_list) {
+			if (q->state == NVMET_TCP_Q_DISCONNECTING) {
+				/* Retry for pending controller teardown */
+				mutex_unlock(&nvmet_tcp_queue_mutex);
+				return NVME_SC_CONNECT_CTRL_BUSY;
+			}
+		}
+		mutex_unlock(&nvmet_tcp_queue_mutex);
 	}
 
 	queue->nr_cmds = sq->size * 2;
-- 
2.35.3