diff -r 859d0e5ac5a2 sys/dev/audio/audio.c
--- a/sys/dev/audio/audio.c	Sun Jan 17 22:02:46 2021 +0000
+++ b/sys/dev/audio/audio.c	Thu Jan 21 01:22:16 2021 +0000
@@ -195,7 +195,7 @@
  * 3: + TRACEs except interrupt
  * 4: + TRACEs including interrupt
  */
-//#define AUDIO_DEBUG 1
+#define AUDIO_DEBUG 1
 
 #if defined(AUDIO_DEBUG)
 
@@ -922,7 +922,7 @@ audioattach(device_t parent, device_t se
 	sc->hw_hdl = hdlp;
 	sc->hw_dev = parent;
 
-	sc->sc_exlock = 1;
+	sc->sc_exlock = curlwp;
 	sc->sc_blk_ms = AUDIO_BLK_MS;
 	SLIST_INIT(&sc->sc_files);
 	cv_init(&sc->sc_exlockcv, "audiolk");
@@ -1110,13 +1110,13 @@ audioattach(device_t parent, device_t se
 #endif
 
 	audiorescan(self, "audio", NULL);
-	sc->sc_exlock = 0;
+	sc->sc_exlock = NULL;
 	return;
 
 bad:
 	/* Clearing hw_if means that device is attached but disabled. */
 	sc->hw_if = NULL;
-	sc->sc_exlock = 0;
+	sc->sc_exlock = NULL;
 	aprint_error_dev(sc->sc_dev, "disabled\n");
 	return;
 }
@@ -1359,7 +1359,8 @@ audiodetach(device_t self, int flags)
 	pmf_device_deregister(self);
 
 	/* Free resources */
-	sc->sc_exlock = 1;
+	KASSERT(sc->sc_exlock == NULL);
+	sc->sc_exlock = curlwp;
 	if (sc->sc_pmixer) {
 		audio_mixer_destroy(sc, sc->sc_pmixer);
 		kmem_free(sc->sc_pmixer, sizeof(*sc->sc_pmixer));
@@ -1470,7 +1471,7 @@ audio_exlock_mutex_enter(struct audio_so
 		return EIO;
 	}
 
-	while (__predict_false(sc->sc_exlock != 0)) {
+	while (__predict_false(sc->sc_exlock != NULL)) {
 		error = cv_wait_sig(&sc->sc_exlockcv, sc->sc_lock);
 		if (sc->sc_dying)
 			error = EIO;
@@ -1481,7 +1482,7 @@ audio_exlock_mutex_enter(struct audio_so
 	}
 
 	/* Acquire */
-	sc->sc_exlock = 1;
+	sc->sc_exlock = curlwp;
 	return 0;
 }
 
@@ -1494,8 +1495,9 @@ audio_exlock_mutex_exit(struct audio_sof
 {
 
 	KASSERT(mutex_owned(sc->sc_lock));
-
-	sc->sc_exlock = 0;
+	KASSERT(sc->sc_exlock == curlwp);
+
+	sc->sc_exlock = NULL;
 	cv_broadcast(&sc->sc_exlockcv);
 	mutex_exit(sc->sc_lock);
 }
@@ -2107,7 +2109,7 @@ audio_open(dev_t dev, struct audio_softc
 	int fd;
 	int error;
 
-	KASSERT(sc->sc_exlock);
+	KASSERT(sc->sc_exlock == curlwp);
 
 	TRACE(1, "%sdev=%s flags=0x%x po=%d ro=%d",
 	    (audiodebug >= 3) ? "start " : "",
@@ -2437,7 +2439,16 @@ audio_unlink(struct audio_softc *sc, aud
 	 * audio_exlock_enter() cannot be used here because we have to go
 	 * forward even if sc_dying is set.
 	 */
-	while (__predict_false(sc->sc_exlock != 0)) {
+	while (__predict_false(sc->sc_exlock != NULL)) {
+		DPRINTF(1, "%s: pid %jd (%s, lid %p%s%s)"
+		    " holding up %s close\n",
+		    __func__,
+		    (intmax_t)sc->sc_exlock->l_proc->p_pid,
+		    sc->sc_exlock->l_proc->p_comm,
+		    sc->sc_exlock,
+		    sc->sc_exlock->l_name ? " " : "",
+		    sc->sc_exlock->l_name ? sc->sc_exlock->l_name : "",
+		    device_xname(sc->sc_dev));
 		error = cv_timedwait_sig(&sc->sc_exlockcv, sc->sc_lock,
 		    mstohz(AUDIO_TIMEOUT));
 		/* XXX what should I do on error? */
@@ -2449,7 +2460,7 @@ audio_unlink(struct audio_softc *sc, aud
 			return error;
 		}
 	}
-	sc->sc_exlock = 1;
+	sc->sc_exlock = curlwp;
 
 	device_active(sc->sc_dev, DVA_SYSTEM);
 
@@ -5090,7 +5101,7 @@ audio_mixer_destroy(struct audio_softc *
 {
 	int bufsize;
 
-	KASSERT(sc->sc_exlock == 1);
+	KASSERT(sc->sc_exlock);
 
 	bufsize = frametobyte(&mixer->hwbuf.fmt, mixer->hwbuf.capacity);
 
diff -r 859d0e5ac5a2 sys/dev/audio/audiovar.h
--- a/sys/dev/audio/audiovar.h	Sun Jan 17 22:02:46 2021 +0000
+++ b/sys/dev/audio/audiovar.h	Thu Jan 21 01:22:16 2021 +0000
@@ -219,7 +219,7 @@ struct audio_softc {
 	 * Critical section.
 	 * Must be protected by sc_lock.
 	 */
-	int sc_exlock;
+	struct lwp *sc_exlock;
 	kcondvar_t sc_exlockcv;
 
 	/*