nvmet-rdma: check for timeout in nvme_rdma_wait_for_cm()

Check whether queue->cm_error holds a value before reading it. This patch
addresses Coverity ID 1373774: unchecked return value.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/rdma.c

@@ -233,8 +233,15 @@ static void nvme_rdma_qp_event(struct ib_event *event, void *context)
 
 static int nvme_rdma_wait_for_cm(struct nvme_rdma_queue *queue)
 {
-	wait_for_completion_interruptible_timeout(&queue->cm_done,
+	int ret;
+
+	ret = wait_for_completion_interruptible_timeout(&queue->cm_done,
 			msecs_to_jiffies(NVME_RDMA_CONNECT_TIMEOUT_MS) + 1);
+	if (ret < 0)
+		return ret;
+	if (ret == 0)
+		return -ETIMEDOUT;
+	WARN_ON_ONCE(queue->cm_error > 0);
 	return queue->cm_error;
 }