dc_newbuf
int dc_newbuf(struct dc_softc *, int, struct mbuf *);
if (dc_newbuf(sc, i, NULL) == ENOBUFS)
dc_newbuf(sc, i, m);
dc_newbuf(sc, i, m);
dc_newbuf(sc, i, m);
dc_newbuf(sc, i, m);