GENL_MIN_ID
return ((uint16_t)(gf - &families[0]) + GENL_MIN_ID);
family_id = hdr->nlmsg_type - GENL_MIN_ID;
gf = &families[family_id - GENL_MIN_ID];
KASSERT(family_id - GENL_MIN_ID < MAX_FAMILIES &&
#define GENL_ID_CTRL GENL_MIN_ID