NIU_FLAGS_VPD_VALID
np->flags |= NIU_FLAGS_VPD_VALID;
np->flags &= ~NIU_FLAGS_VPD_VALID;
np->flags &= ~NIU_FLAGS_VPD_VALID;
if (np->flags & NIU_FLAGS_VPD_VALID) {
if (!(np->flags & NIU_FLAGS_VPD_VALID)) {