mixer_ev
struct mixer_ev *next;
sizeof(struct mixer_ev), M_DEVBUF, M_WAITOK | M_ZERO);
free(sc->mix_evbuf, M_DEVBUF, sc->mix_nent * sizeof(struct mixer_ev));
struct mixer_ev *mix_evbuf; /* per mixer-control event */
struct mixer_ev *mix_pending; /* list of changed controls */
struct mixer_ev *e;
struct mixer_ev *e;