NLSE_ATTR_SUBSYSTEM
{ .type = NLSE_ATTR_SUBSYSTEM, .off = _OUT(subsystem), .cb = snl_attr_get_string },
nlattr_add_string(&nw, NLSE_ATTR_SUBSYSTEM, subsystem);
{ .type = NLSE_ATTR_SUBSYSTEM, .off = _OUT(subsystem), .cb = snl_attr_get_string },
{ .type = NLSE_ATTR_SUBSYSTEM, .off = _OUT(subsystem), .cb = snl_attr_get_string },