Re: [ 42/66] ALSA: Avoid endless sleep after disconnect

[Takashi Iwai]

At Wed, 14 Nov 2012 20:10:47 -0800,
Greg Kroah-Hartman wrote:
> 
> 3.6-stable review patch.  If anyone has any objections, please let me know.

It turned out that this patch series for fixing USB-audio
disconnection races need two more commits.  One is already in Linus
tree,

    commit 8bb4d9ce08b0a92ca174e41d92c180328f86173f
        ALSA: Fix card refcount unbalance
    
and another is included in the pull request I sent out to Linus right
now,

    commit 10e44239f67d0b6fb74006e61a7e883b8075247a
        ALSA: usb-audio: Fix mutex deadlock at disconnection
    
Please pick them up when possible, too.
Sorry for inconvenience.


thanks,

Takashi


> 
> ------------------
> 
> 
> From: Takashi Iwai <tiwai@xxxxxxx>
> 
> commit 0914f7961babbf28aaa2f19b453951fb4841c03f upstream.
> 
> When disconnect callback is called, each component should wake up
> sleepers and check card->shutdown flag for avoiding the endless sleep
> blocking the proper resource release.
> 
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  sound/core/control.c     |    2 ++
>  sound/core/hwdep.c       |    7 +++++++
>  sound/core/oss/pcm_oss.c |    4 ++++
>  sound/core/pcm.c         |    6 +++++-
>  sound/core/pcm_native.c  |    8 ++++++++
>  sound/core/rawmidi.c     |   20 ++++++++++++++++++++
>  6 files changed, 46 insertions(+), 1 deletion(-)
> 
> --- a/sound/core/control.c
> +++ b/sound/core/control.c
> @@ -1436,6 +1436,8 @@ static ssize_t snd_ctl_read(struct file
>  			spin_unlock_irq(&ctl->read_lock);
>  			schedule();
>  			remove_wait_queue(&ctl->change_sleep, &wait);
> +			if (ctl->card->shutdown)
> +				return -ENODEV;
>  			if (signal_pending(current))
>  				return -ERESTARTSYS;
>  			spin_lock_irq(&ctl->read_lock);
> --- a/sound/core/hwdep.c
> +++ b/sound/core/hwdep.c
> @@ -131,6 +131,10 @@ static int snd_hwdep_open(struct inode *
>  		mutex_unlock(&hw->open_mutex);
>  		schedule();
>  		mutex_lock(&hw->open_mutex);
> +		if (hw->card->shutdown) {
> +			err = -ENODEV;
> +			break;
> +		}
>  		if (signal_pending(current)) {
>  			err = -ERESTARTSYS;
>  			break;
> @@ -462,12 +466,15 @@ static int snd_hwdep_dev_disconnect(stru
>  		mutex_unlock(&register_mutex);
>  		return -EINVAL;
>  	}
> +	mutex_lock(&hwdep->open_mutex);
> +	wake_up(&hwdep->open_wait);
>  #ifdef CONFIG_SND_OSSEMUL
>  	if (hwdep->ossreg)
>  		snd_unregister_oss_device(hwdep->oss_type, hwdep->card, hwdep->device);
>  #endif
>  	snd_unregister_device(SNDRV_DEVICE_TYPE_HWDEP, hwdep->card, hwdep->device);
>  	list_del_init(&hwdep->list);
> +	mutex_unlock(&hwdep->open_mutex);
>  	mutex_unlock(&register_mutex);
>  	return 0;
>  }
> --- a/sound/core/oss/pcm_oss.c
> +++ b/sound/core/oss/pcm_oss.c
> @@ -2441,6 +2441,10 @@ static int snd_pcm_oss_open(struct inode
>  		mutex_unlock(&pcm->open_mutex);
>  		schedule();
>  		mutex_lock(&pcm->open_mutex);
> +		if (pcm->card->shutdown) {
> +			err = -ENODEV;
> +			break;
> +		}
>  		if (signal_pending(current)) {
>  			err = -ERESTARTSYS;
>  			break;
> --- a/sound/core/pcm.c
> +++ b/sound/core/pcm.c
> @@ -1087,12 +1087,16 @@ static int snd_pcm_dev_disconnect(struct
>  		goto unlock;
>  
>  	mutex_lock(&pcm->open_mutex);
> +	wake_up(&pcm->open_wait);
>  	list_del_init(&pcm->list);
>  	for (cidx = 0; cidx < 2; cidx++)
>  		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next) {
>  			snd_pcm_stream_lock_irq(substream);
> -			if (substream->runtime)
> +			if (substream->runtime) {
>  				substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
> +				wake_up(&substream->runtime->sleep);
> +				wake_up(&substream->runtime->tsleep);
> +			}
>  			snd_pcm_stream_unlock_irq(substream);
>  		}
>  	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -1518,6 +1518,10 @@ static int snd_pcm_drain(struct snd_pcm_
>  		down_read(&snd_pcm_link_rwsem);
>  		snd_pcm_stream_lock_irq(substream);
>  		remove_wait_queue(&to_check->sleep, &wait);
> +		if (card->shutdown) {
> +			result = -ENODEV;
> +			break;
> +		}
>  		if (tout == 0) {
>  			if (substream->runtime->status->state == SNDRV_PCM_STATE_SUSPENDED)
>  				result = -ESTRPIPE;
> @@ -2168,6 +2172,10 @@ static int snd_pcm_open(struct file *fil
>  		mutex_unlock(&pcm->open_mutex);
>  		schedule();
>  		mutex_lock(&pcm->open_mutex);
> +		if (pcm->card->shutdown) {
> +			err = -ENODEV;
> +			break;
> +		}
>  		if (signal_pending(current)) {
>  			err = -ERESTARTSYS;
>  			break;
> --- a/sound/core/rawmidi.c
> +++ b/sound/core/rawmidi.c
> @@ -424,6 +424,10 @@ static int snd_rawmidi_open(struct inode
>  		mutex_unlock(&rmidi->open_mutex);
>  		schedule();
>  		mutex_lock(&rmidi->open_mutex);
> +		if (rmidi->card->shutdown) {
> +			err = -ENODEV;
> +			break;
> +		}
>  		if (signal_pending(current)) {
>  			err = -ERESTARTSYS;
>  			break;
> @@ -995,6 +999,8 @@ static ssize_t snd_rawmidi_read(struct f
>  			spin_unlock_irq(&runtime->lock);
>  			schedule();
>  			remove_wait_queue(&runtime->sleep, &wait);
> +			if (rfile->rmidi->card->shutdown)
> +				return -ENODEV;
>  			if (signal_pending(current))
>  				return result > 0 ? result : -ERESTARTSYS;
>  			if (!runtime->avail)
> @@ -1238,6 +1244,8 @@ static ssize_t snd_rawmidi_write(struct
>  			spin_unlock_irq(&runtime->lock);
>  			timeout = schedule_timeout(30 * HZ);
>  			remove_wait_queue(&runtime->sleep, &wait);
> +			if (rfile->rmidi->card->shutdown)
> +				return -ENODEV;
>  			if (signal_pending(current))
>  				return result > 0 ? result : -ERESTARTSYS;
>  			if (!runtime->avail && !timeout)
> @@ -1613,9 +1621,20 @@ static int snd_rawmidi_dev_register(stru
>  static int snd_rawmidi_dev_disconnect(struct snd_device *device)
>  {
>  	struct snd_rawmidi *rmidi = device->device_data;
> +	int dir;
>  
>  	mutex_lock(&register_mutex);
> +	mutex_lock(&rmidi->open_mutex);
> +	wake_up(&rmidi->open_wait);
>  	list_del_init(&rmidi->list);
> +	for (dir = 0; dir < 2; dir++) {
> +		struct snd_rawmidi_substream *s;
> +		list_for_each_entry(s, &rmidi->streams[dir].substreams, list) {
> +			if (s->runtime)
> +				wake_up(&s->runtime->sleep);
> +		}
> +	}
> +
>  #ifdef CONFIG_SND_OSSEMUL
>  	if (rmidi->ossreg) {
>  		if ((int)rmidi->device == midi_map[rmidi->card->number]) {
> @@ -1630,6 +1649,7 @@ static int snd_rawmidi_dev_disconnect(st
>  	}
>  #endif /* CONFIG_SND_OSSEMUL */
>  	snd_unregister_device(SNDRV_DEVICE_TYPE_RAWMIDI, rmidi->card, rmidi->device);
> +	mutex_unlock(&rmidi->open_mutex);
>  	mutex_unlock(&register_mutex);
>  	return 0;
>  }
> 
> 
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