sound: Retire snd_mixer->busy

Does not really serve any real purpose. It gets set on mixer_open() and
unset on mixer_close(), so it essentially tells us whether the mixer is
open or not.

mixer_close() uses it to return EBADF in case the mixer is not busied,
as in, the mixer has not been open()'d yet. This is redundant. The other
place where this is used is to decide whether to serve an ioctl issued
by userland, in which case it won't if, again, the mixer has not been
busied (i.e., opened). Again, seems redundant.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D53859

sys/dev/sound/pci/es137x.c

@@ -1540,10 +1540,6 @@ sysctl_es137x_single_pcm_mixer(SYSCTL_HANDLER_ARGS)
 		PCM_RELEASE_QUICK(d);
 		return (ENODEV);
 	}
-	if (mixer_busy(m) != 0) {
-		PCM_RELEASE_QUICK(d);
-		return (EBUSY);
-	}
 	level = mix_get(m, SOUND_MIXER_PCM);
 	recsrc = mix_getrecsrc(m);
 	if (level < 0 || recsrc < 0) {

sys/dev/sound/pcm/mixer.c

@@ -48,7 +48,6 @@ SYSCTL_INT(_hw_snd, OID_AUTO, vpc_mixer_bypass, CTLFLAG_RWTUN,
 struct snd_mixer {
 	KOBJ_FIELDS;
 	void *devinfo;
-	int busy;
 	int hwvol_mixer;
 	int hwvol_step;
 	int type;
@@ -651,7 +650,6 @@ mixer_obj_create(device_t dev, kobj_class_t cls, void *devinfo,
 	    "primary pcm mixer" : "secondary pcm mixer", MTX_DEF);
 	m->type = type;
 	m->devinfo = devinfo;
-	m->busy = 0;
 	m->dev = dev;
 	for (i = 0; i < nitems(m->parent); i++) {
 		m->parent[i] = SOUND_MIXER_NONE;
@@ -947,14 +945,6 @@ mixer_hwvol_step(device_t dev, int left_step, int right_step)
 	mtx_unlock(&m->lock);
 }
 
-int
-mixer_busy(struct snd_mixer *m)
-{
-	KASSERT(m != NULL, ("NULL snd_mixer"));
-
-	return (m->busy);
-}
-
 int
 mix_set(struct snd_mixer *m, u_int dev, u_int left, u_int right)
 {
@@ -1035,12 +1025,6 @@ mixer_open(struct cdev *i_dev, int flags, int mode, struct thread *td)
 	if (!PCM_REGISTERED(d))
 		return (EBADF);
 
-	/* XXX Need Giant magic entry ??? */
-
-	mtx_lock(&m->lock);
-	m->busy = 1;
-	mtx_unlock(&m->lock);
-
 	return (0);
 }
 
@@ -1049,7 +1033,6 @@ mixer_close(struct cdev *i_dev, int flags, int mode, struct thread *td)
 {
 	struct snddev_info *d;
 	struct snd_mixer *m;
-	int ret;
 
 	if (i_dev == NULL || i_dev->si_drv1 == NULL)
 		return (EBADF);
@@ -1059,14 +1042,7 @@ mixer_close(struct cdev *i_dev, int flags, int mode, struct thread *td)
 	if (!PCM_REGISTERED(d))
 		return (EBADF);
 
-	/* XXX Need Giant magic entry ??? */
-
-	mtx_lock(&m->lock);
-	ret = (m->busy == 0) ? EBADF : 0;
-	m->busy = 0;
-	mtx_unlock(&m->lock);
-
-	return (ret);
+	return (0);
 }
 
 static int
@@ -1262,10 +1238,6 @@ mixer_ioctl_cmd(struct cdev *i_dev, u_long cmd, caddr_t arg, int mode,
 		return (EBADF);
 
 	mtx_lock(&m->lock);
-	if (from == MIXER_CMD_CDEV && !m->busy) {
-		mtx_unlock(&m->lock);
-		return (EBADF);
-	}
 	switch (cmd) {
 	case SNDCTL_DSP_GET_RECSRC_NAMES:
 		bcopy((void *)&m->enuminfo, arg, sizeof(oss_mixer_enuminfo));

sys/dev/sound/pcm/mixer.h

@@ -45,8 +45,6 @@ void mixer_hwvol_mute(device_t dev);
 void mixer_hwvol_step_locked(struct snd_mixer *m, int l_step, int r_step);
 void mixer_hwvol_step(device_t dev, int left_step, int right_step);
 
-int mixer_busy(struct snd_mixer *m);
-
 int mix_set(struct snd_mixer *m, u_int dev, u_int left, u_int right);
 int mix_get(struct snd_mixer *m, u_int dev);
 int mix_setrecsrc(struct snd_mixer *m, u_int32_t src);