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