batadv_v_ogm_len
unsigned int ogm_len = batadv_v_ogm_len(skb);
hard_iface->bat_v.aggr_len -= batadv_v_ogm_len(skb);
ogm_len = batadv_v_ogm_len(skb);
hard_iface->bat_v.aggr_len += batadv_v_ogm_len(skb);