int interface_add_data(struct interface *iface, const struct blob_attr *data);
int interface_parse_data(struct interface *iface, const struct blob_attr *attr);
-void interface_update_start(struct interface *iface);
+void interface_update_start(struct interface *iface, const bool keep_old);
void interface_update_complete(struct interface *iface);
void interface_start_pending(void);