primary_smach
dsmp = primary_smach(isv6);
if (primary_smach(isv6) == NULL &&
(alt_primary = primary_smach(!isv6)) != NULL) {
if ((old_primary = primary_smach(dsmp->dsm_isv6)) != NULL)
alt_primary = primary_smach(!dsmp->dsm_isv6);
dhcp_smach_t *primary_smach(boolean_t);