GUS_LOCKED
sc->sc_flags |= GUS_LOCKED;
KASSERT((sc->sc_flags & (GUS_DMAOUT_ACTIVE | GUS_LOCKED)) == 0);
sc->sc_flags &= ~GUS_LOCKED;
if (sc->sc_dmaoutintr && !(sc->sc_flags & GUS_LOCKED)) {
if (sc->sc_playbuf == sc->sc_dmabuf && (sc->sc_flags & GUS_LOCKED)) {
sc->sc_flags &= ~(GUS_DMAOUT_ACTIVE|GUS_LOCKED);