UDAV_FLAG_LINK
sc->sc_flags |= UDAV_FLAG_LINK;
if ((sc->sc_flags & UDAV_FLAG_LINK) == 0) {
sc->sc_flags &= ~UDAV_FLAG_LINK;
sc->sc_flags &= ~UDAV_FLAG_LINK;
if ((sc->sc_flags & UDAV_FLAG_LINK) == 0
sc->sc_flags |= UDAV_FLAG_LINK;