diff --git a/sys/dev/sound/pci/hda/hdaa.c b/sys/dev/sound/pci/hda/hdaa.c
--- a/sys/dev/sound/pci/hda/hdaa.c
+++ b/sys/dev/sound/pci/hda/hdaa.c
@@ -6458,10 +6458,10 @@
 		device_printf(dev, "Reconfiguration...\n");
 	);
 
-	bus_topo_lock();
+	SND_LOCK();
 
 	if ((error = device_delete_children(dev)) != 0) {
-		bus_topo_unlock();
+		SND_UNLOCK();
 		return (error);
 	}
 	hdaa_lock(devinfo);
@@ -6473,7 +6473,7 @@
 		device_printf(dev, "Reconfiguration done\n");
 	);
 
-	bus_topo_unlock();
+	SND_UNLOCK();
 
 	return (0);
 }
diff --git a/sys/dev/sound/pci/hda/hdac.c b/sys/dev/sound/pci/hda/hdac.c
--- a/sys/dev/sound/pci/hda/hdac.c
+++ b/sys/dev/sound/pci/hda/hdac.c
@@ -1401,10 +1401,10 @@
 		return (0);
 	}
 
-	bus_topo_lock();
+	SND_LOCK();
 
 	if ((err = device_get_children(dev, &devlist, &devcount)) != 0) {
-		bus_topo_unlock();
+		SND_UNLOCK();
 		return (err);
 	}
 
@@ -1413,7 +1413,7 @@
 		HDAC_PINDUMP(devlist[i]);
 	hdac_unlock(sc);
 
-	bus_topo_unlock();
+	SND_UNLOCK();
 
 	free(devlist, M_TEMP);
 	return (0);
diff --git a/sys/dev/sound/pcm/channel.c b/sys/dev/sound/pcm/channel.c
--- a/sys/dev/sound/pcm/channel.c
+++ b/sys/dev/sound/pcm/channel.c
@@ -128,6 +128,7 @@
 	struct pcm_channel *c;
 	int i;
 
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
@@ -146,6 +147,7 @@
 		PCM_RELEASE(d);
 		PCM_UNLOCK(d);
 	}
+	SND_UNLOCK();
 }
 
 static int
@@ -166,7 +168,7 @@
 	return (0);
 }
 SYSCTL_PROC(_hw_snd, OID_AUTO, vpc_0db,
-    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_NEEDGIANT, 0, sizeof(int),
+    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, sizeof(int),
     sysctl_hw_snd_vpc_0db, "I",
     "0db relative level");
 
@@ -186,7 +188,7 @@
 	return (0);
 }
 SYSCTL_PROC(_hw_snd, OID_AUTO, vpc_reset,
-    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, sizeof(int),
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, sizeof(int),
     sysctl_hw_snd_vpc_reset, "I",
     "reset volume on all channels");
 
diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c
--- a/sys/dev/sound/pcm/dsp.c
+++ b/sys/dev/sound/pcm/dsp.c
@@ -1927,7 +1927,7 @@
 	}
 	return;
 found:
-	bus_topo_lock();
+	SND_LOCK();
 	d = devclass_get_softc(pcm_devclass, snd_unit);
 	/*
 	 * If we only have a single soundcard attached and we detach it right
@@ -1939,7 +1939,7 @@
 		*dev = d->dsp_dev;
 		dev_ref(*dev);
 	}
-	bus_topo_unlock();
+	SND_UNLOCK();
 }
 
 static void
@@ -2016,6 +2016,7 @@
 	if (ai->dev == -1 && i_dev->si_devsw != &dsp_cdevsw)
 		return (EINVAL);
 
+	SND_LOCK();
 	for (unit = 0; pcm_devclass != NULL &&
 	    unit < devclass_get_maxunit(pcm_devclass); unit++) {
 		d = devclass_get_softc(pcm_devclass, unit);
@@ -2023,6 +2024,7 @@
 			if ((ai->dev == -1 && unit == snd_unit) ||
 			    ai->dev == unit) {
 				dsp_oss_audioinfo_unavail(ai, unit);
+				SND_UNLOCK();
 				return (0);
 			} else {
 				d = NULL;
@@ -2041,6 +2043,7 @@
 			d = NULL;
 		}
 	}
+	SND_UNLOCK();
 
 	/* Exhausted the search -- nothing is locked, so return. */
 	if (d == NULL)
@@ -2197,6 +2200,7 @@
 	 * Search for the requested audio device (channel).  Start by
 	 * iterating over pcm devices.
 	 */ 
+	SND_LOCK();
 	for (unit = 0; pcm_devclass != NULL &&
 	    unit < devclass_get_maxunit(pcm_devclass); unit++) {
 		d = devclass_get_softc(pcm_devclass, unit);
@@ -2346,9 +2350,11 @@
 
 		CHN_UNLOCK(ch);
 		PCM_UNLOCK(d);
+		SND_UNLOCK();
 
 		return (0);
 	}
+	SND_UNLOCK();
 
 	/* Exhausted the search -- nothing is locked, so return. */
 	return (EINVAL);
diff --git a/sys/dev/sound/pcm/feeder_rate.c b/sys/dev/sound/pcm/feeder_rate.c
--- a/sys/dev/sound/pcm/feeder_rate.c
+++ b/sys/dev/sound/pcm/feeder_rate.c
@@ -258,6 +258,7 @@
 	 * set resampler quality if and only if it is exist as
 	 * part of feeder chains and the channel is idle.
 	 */
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
@@ -279,11 +280,12 @@
 		PCM_RELEASE(d);
 		PCM_UNLOCK(d);
 	}
+	SND_UNLOCK();
 
 	return (0);
 }
 SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_quality,
-    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_NEEDGIANT, 0, sizeof(int),
+    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, sizeof(int),
     sysctl_hw_snd_feeder_rate_quality, "I",
     "sample rate converter quality ("__XSTRING(Z_QUALITY_MIN)"=low .. "
     __XSTRING(Z_QUALITY_MAX)"=high)");
diff --git a/sys/dev/sound/pcm/mixer.c b/sys/dev/sound/pcm/mixer.c
--- a/sys/dev/sound/pcm/mixer.c
+++ b/sys/dev/sound/pcm/mixer.c
@@ -1362,14 +1362,14 @@
 	if (*dev != NULL)
 		return;
 	if (strcmp(name, "mixer") == 0) {
-		bus_topo_lock();
+		SND_LOCK();
 		d = devclass_get_softc(pcm_devclass, snd_unit);
 		/* See related comment in dsp_clone(). */
 		if (d != NULL && PCM_REGISTERED(d) && d->mixer_dev != NULL) {
 			*dev = d->mixer_dev;
 			dev_ref(*dev);
 		}
-		bus_topo_unlock();
+		SND_UNLOCK();
 	}
 }
 
@@ -1444,12 +1444,14 @@
 	 * There's a 1:1 relationship between mixers and PCM devices, so
 	 * begin by iterating over PCM devices and search for our mixer.
 	 */
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
 		if (!PCM_REGISTERED(d)) {
 			if ((mi->dev == -1 && i == snd_unit) || mi->dev == i) {
 				mixer_oss_mixerinfo_unavail(mi, i);
+				SND_UNLOCK();
 				return (0);
 			} else
 				continue;
@@ -1470,6 +1472,7 @@
 		if (d->mixer_dev->si_drv1 == NULL) {
 			mixer_oss_mixerinfo_unavail(mi, i);
 			PCM_UNLOCK(d);
+			SND_UNLOCK();
 			return (0);
 		}
 
@@ -1550,8 +1553,10 @@
 
 		PCM_UNLOCK(d);
 
+		SND_UNLOCK();
 		return (0);
 	}
+	SND_UNLOCK();
 
 	return (EINVAL);
 }
diff --git a/sys/dev/sound/pcm/sound.h b/sys/dev/sound/pcm/sound.h
--- a/sys/dev/sound/pcm/sound.h
+++ b/sys/dev/sound/pcm/sound.h
@@ -71,6 +71,7 @@
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/condvar.h>
+#include <sys/sx.h>
 
 #ifndef KOBJMETHOD_END
 #define KOBJMETHOD_END	{ NULL, NULL }
@@ -160,6 +161,7 @@
 
 #define DSP_DEFAULT_SPEED	8000
 
+extern struct sx snd_sx;
 extern int snd_unit;
 extern int snd_verbose;
 extern devclass_t pcm_devclass;
@@ -257,6 +259,9 @@
 #define	PCM_MODE_PLAY		0x02
 #define	PCM_MODE_REC		0x04
 
+#define	SND_LOCK()		sx_xlock(&snd_sx)
+#define	SND_UNLOCK()		sx_xunlock(&snd_sx)
+
 #define PCM_LOCKOWNED(d)	mtx_owned((d)->lock)
 #define	PCM_LOCK(d)		mtx_lock((d)->lock)
 #define	PCM_UNLOCK(d)		mtx_unlock((d)->lock)
diff --git a/sys/dev/sound/pcm/sound.c b/sys/dev/sound/pcm/sound.c
--- a/sys/dev/sound/pcm/sound.c
+++ b/sys/dev/sound/pcm/sound.c
@@ -50,6 +50,9 @@
 
 int snd_unit = -1;
 
+struct sx snd_sx;
+SX_SYSINIT(snd_sx, &snd_sx, "snd sx");
+
 static int snd_unit_auto = -1;
 SYSCTL_INT(_hw_snd, OID_AUTO, default_auto, CTLFLAG_RWTUN,
     &snd_unit_auto, 0, "assign default unit to a newly attached device");
@@ -119,14 +122,16 @@
 		d = devclass_get_softc(pcm_devclass, unit);
 		if (!PCM_REGISTERED(d) || CHN_EMPTY(d, channels.pcm))
 			return EINVAL;
+		SND_LOCK();
 		snd_unit = unit;
 		snd_unit_auto = 0;
+		SND_UNLOCK();
 	}
 	return (error);
 }
 /* XXX: do we need a way to let the user change the default unit? */
 SYSCTL_PROC(_hw_snd, OID_AUTO, default_unit,
-    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_ANYBODY | CTLFLAG_NEEDGIANT, 0,
+    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE, 0,
     sizeof(int), sysctl_hw_snd_default_unit, "I",
     "default sound device");
 
@@ -213,6 +218,7 @@
 
 	best = -1;
 	bestprio = -100;
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
@@ -228,6 +234,8 @@
 			bestprio = prio;
 		}
 	}
+	SND_UNLOCK();
+
 	return (best);
 }
 
@@ -557,6 +565,7 @@
 
 	j = 0;
 
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
@@ -583,6 +592,7 @@
 
 		PCM_UNLOCK(d);
 	}
+	SND_UNLOCK();
 
 	si->numsynths = 0;	/* OSSv4 docs:  this field is obsolete */
 	/**
@@ -603,9 +613,11 @@
 	 * break if they try to loop through all mixers and some of them are
 	 * not available.
 	 */
+	SND_LOCK();
 	si->nummixers = devclass_get_maxunit(pcm_devclass);
 	si->numcards = devclass_get_maxunit(pcm_devclass);
 	si->numaudios = devclass_get_maxunit(pcm_devclass);
+	SND_UNLOCK();
 		/* OSSv4 docs:	Intended only for test apps; API doesn't
 		   really have much of a concept of cards.  Shouldn't be
 		   used by applications. */
@@ -631,6 +643,7 @@
 	struct snddev_info *d;
 	int i;
 
+	SND_LOCK();
 	for (i = 0; pcm_devclass != NULL &&
 	    i < devclass_get_maxunit(pcm_devclass); i++) {
 		d = devclass_get_softc(pcm_devclass, i);
@@ -658,8 +671,11 @@
 			PCM_UNLOCK(d);
 		}
 
+		SND_UNLOCK();
 		return (0);
 	}
+	SND_UNLOCK();
+
 	return (ENXIO);
 }
 
diff --git a/sys/dev/sound/pcm/vchan.c b/sys/dev/sound/pcm/vchan.c
--- a/sys/dev/sound/pcm/vchan.c
+++ b/sys/dev/sound/pcm/vchan.c
@@ -825,6 +825,7 @@
 	if (error != 0 || req->newptr == NULL)
 		return (error);
 
+	SND_LOCK();
 	snd_vchans_enable = v >= 1;
 
 	for (i = 0; pcm_devclass != NULL &&
@@ -842,11 +843,12 @@
 			d->flags &= ~(SD_F_PVCHANS | SD_F_RVCHANS);
 		PCM_RELEASE_QUICK(d);
 	}
+	SND_UNLOCK();
 
 	return (0);
 }
 SYSCTL_PROC(_hw_snd, OID_AUTO, vchans_enable,
-    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_NEEDGIANT, 0, sizeof(int),
+    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, sizeof(int),
     sysctl_hw_snd_vchans_enable, "I", "global virtual channel switch");
 
 void