mac_add_vlan_tag
mp_chain = mac_add_vlan_tag(mp_chain, 0,
(mp) = mac_add_vlan_tag((mp), 0, vid); \
if ((mp = mac_add_vlan_tag(mp, pri, vid)) == NULL) {
extern mblk_t *mac_add_vlan_tag(mblk_t *, uint_t, uint16_t);