IFLA_MACVLAN_MACADDR_DATA
if (data[IFLA_MACVLAN_MACADDR_DATA]) {
head = nla_data(data[IFLA_MACVLAN_MACADDR_DATA]);
len = nla_len(data[IFLA_MACVLAN_MACADDR_DATA]);
if (!data[IFLA_MACVLAN_MACADDR_DATA])
head = nla_data(data[IFLA_MACVLAN_MACADDR_DATA]);
len = nla_len(data[IFLA_MACVLAN_MACADDR_DATA]);
nest = nla_nest_start_noflag(skb, IFLA_MACVLAN_MACADDR_DATA);
[IFLA_MACVLAN_MACADDR_DATA] = { .type = NLA_NESTED },