Re: Audio subsystem versus unplugging uaudio

[Julian Coleman <jdc%coris.org.uk@localhost>]

Hello,

> I ran into a problem with uaudio, but I'll have a look at uaudio_detach().

With a hint from skrll@, I looked at uaudio_detach().  We already have
code in uaudio_halt_out_dma() and uaudio_halt_in_dma() to stop any playback
or recording, so it looks like we can reuse these when detaching.  With the
attached patch, I no longer see the panics when removing a uaudio device
when playback is in progress.

Regards,

Julian

Index: uaudio.c
===================================================================
RCS file: /cvsroot/src/sys/dev/usb/uaudio.c,v
retrieving revision 1.165
diff -u -r1.165 uaudio.c
--- uaudio.c	14 Mar 2020 02:35:33 -0000	1.165
+++ uaudio.c	26 Dec 2020 08:17:35 -0000
@@ -343,6 +343,8 @@
 	 const audio_params_t *);
 Static int	uaudio_halt_in_dma(void *);
 Static int	uaudio_halt_out_dma(void *);
+Static void	uaudio_halt_in_dma_unlocked(struct uaudio_softc *);
+Static void	uaudio_halt_out_dma_unlocked(struct uaudio_softc *);
 Static int	uaudio_getdev(void *, struct audio_device *);
 Static int	uaudio_mixer_set_port(void *, mixer_ctrl_t *);
 Static int	uaudio_mixer_get_port(void *, mixer_ctrl_t *);
@@ -519,10 +521,13 @@
 	struct uaudio_softc *sc = device_private(self);
 	int rv = 0;
 
+	sc->sc_dying = 1;
+
 	pmf_device_deregister(self);
 
 	/* Wait for outstanding requests to complete. */
-	usbd_delay_ms(sc->sc_udev, UAUDIO_NCHANBUFS * UAUDIO_NFRAMES);
+	uaudio_halt_out_dma_unlocked(sc);
+	uaudio_halt_in_dma_unlocked(sc);
 
 	if (sc->sc_audiodev != NULL)
 		rv = config_detach(sc->sc_audiodev, flags);
@@ -2167,15 +2172,21 @@
 	DPRINTF("%s", "enter\n");
 
 	mutex_exit(&sc->sc_intr_lock);
+	uaudio_halt_out_dma_unlocked(sc);
+	mutex_enter(&sc->sc_intr_lock);
+
+	return 0;
+}
+
+Static void
+uaudio_halt_out_dma_unlocked(struct uaudio_softc *sc)
+{
 	if (sc->sc_playchan.pipe != NULL) {
 		uaudio_chan_abort(sc, &sc->sc_playchan);
 		uaudio_chan_free_buffers(sc, &sc->sc_playchan);
 		uaudio_chan_close(sc, &sc->sc_playchan);
 		sc->sc_playchan.intr = NULL;
 	}
-	mutex_enter(&sc->sc_intr_lock);
-
-	return 0;
 }
 
 Static int
@@ -2186,15 +2197,21 @@
 	DPRINTF("%s", "enter\n");
 
 	mutex_exit(&sc->sc_intr_lock);
+	uaudio_halt_in_dma_unlocked(sc);
+	mutex_enter(&sc->sc_intr_lock);
+
+	return 0;
+}
+
+Static void
+uaudio_halt_in_dma_unlocked(struct uaudio_softc *sc)
+{
 	if (sc->sc_recchan.pipe != NULL) {
 		uaudio_chan_abort(sc, &sc->sc_recchan);
 		uaudio_chan_free_buffers(sc, &sc->sc_recchan);
 		uaudio_chan_close(sc, &sc->sc_recchan);
 		sc->sc_recchan.intr = NULL;
 	}
-	mutex_enter(&sc->sc_intr_lock);
-
-	return 0;
 }
 
 Static int