[alsa-devel] USB audio devices & kernel panics

[Takashi Iwai]

At Fri, 18 Feb 2011 09:35:10 -0500,
Moustafa Chamli wrote:
> 
> Hello,
> 
> I was told to ask at the alsa-dev list as to if there's a known bug and
> fix with USB audio devices causing kernel panics.  A bug was reported on
> Launchpad stating that it is fully reproducible:
> 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/715318

Could you try the patch below?


thanks,

Takashi

---
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 800f7cb..b452aa4 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -323,6 +323,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
 		return -ENOMEM;
 	}
 
+	init_mutex(&chip->shutdown_mutex);
 	chip->index = idx;
 	chip->dev = dev;
 	chip->card = card;
@@ -531,6 +532,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
 	chip = ptr;
 	card = chip->card;
 	mutex_lock(&register_mutex);
+	mutex_lock(&chip->shutdown_mutex);
 	chip->shutdown = 1;
 	chip->num_interfaces--;
 	if (chip->num_interfaces <= 0) {
@@ -548,9 +550,11 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
 			snd_usb_mixer_disconnect(p);
 		}
 		usb_chip[chip->index] = NULL;
+		mutex_unlock(&chip->shutdown_mutex);
 		mutex_unlock(&register_mutex);
 		snd_card_free_when_closed(card);
 	} else {
+		mutex_unlock(&chip->shutdown_mutex);
 		mutex_unlock(&register_mutex);
 	}
 }
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 4132522..ca4de49 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -385,8 +385,10 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_audiofmt = NULL;
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
+	mutex_lock(&subs->stream->chip->shutdown_mutex);
 	if (!subs->stream->chip->shutdown)
 		snd_usb_release_substream_urbs(subs, 0);
+	mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
 
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index db3eb21..6e66fff 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -36,6 +36,7 @@ struct snd_usb_audio {
 	struct snd_card *card;
 	u32 usb_id;
 	int shutdown;
+	struct mutex shutdown_mutex;
 	unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */
 	int num_interfaces;
 	int num_suspended_intf;