nvme-tcp: fix timeout handler

Currently, we have several problems with the timeout
handler:
1. If we timeout on the controller establishment flow, we will hang
because we don't execute the error recovery (and we shouldn't because
the create_ctrl flow needs to fail and cleanup on its own)
2. We might also hang if we get a disconnet on a queue while the
controller is already deleting. This racy flow can cause the controller
disable/shutdown admin command to hang.

We cannot complete a timed out request from the timeout handler without
mutual exclusion from the teardown flow (e.g. nvme_rdma_error_recovery_work).
So we serialize it in the timeout handler and teardown io and admin
queues to guarantee that no one races with us from completing the
request.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/tcp.c

@@ -1948,20 +1948,23 @@ nvme_tcp_timeout(struct request *rq, bool reserved)
 	struct nvme_tcp_ctrl *ctrl = req->queue->ctrl;
 	struct nvme_tcp_cmd_pdu *pdu = req->pdu;
 
-	dev_dbg(ctrl->ctrl.device,
+	dev_warn(ctrl->ctrl.device,
 		"queue %d: timeout request %#x type %d\n",
-		nvme_tcp_queue_id(req->queue), rq->tag,
-		pdu->hdr.type);
+		nvme_tcp_queue_id(req->queue), rq->tag, pdu->hdr.type);
 
 	if (ctrl->ctrl.state != NVME_CTRL_LIVE) {
-		union nvme_result res = {};
-
-		nvme_req(rq)->flags |= NVME_REQ_CANCELLED;
-		nvme_end_request(rq, cpu_to_le16(NVME_SC_ABORT_REQ), res);
+		/*
+		 * Teardown immediately if controller times out while starting
+		 * or we are already started error recovery. all outstanding
+		 * requests are completed on shutdown, so we return BLK_EH_DONE.
+		 */
+		flush_work(&ctrl->err_work);
+		nvme_tcp_teardown_io_queues(&ctrl->ctrl, false);
+		nvme_tcp_teardown_admin_queue(&ctrl->ctrl, false);
 		return BLK_EH_DONE;
 	}
 
-	/* queue error recovery */
+	dev_warn(ctrl->ctrl.device, "starting error recovery\n");
 	nvme_tcp_error_recovery(&ctrl->ctrl);
 
 	return BLK_EH_RESET_TIMER;