+void ena_debugfs_init(struct net_device *dev)
+{
+	struct ena_adapter *adapter = netdev_priv(dev);
+
+	adapter->debugfs_base =
+		debugfs_create_dir(dev_name(&adapter->pdev->dev), NULL);
+	if (IS_ERR(adapter->debugfs_base))
+		netdev_err(dev, "Failed to create debugfs dir\n");

Don't check return codes from debugfs_ calls. It does not matter if it
fails, it is just debug, and all debugfs_ calls are happy to take a
NULL pointer, ERR_PTR() etc.

	Andrew