At Wed, 14 Nov 2012 11:44:44 +0100, Matthieu CASTET wrote: > > A deadlock was detected with this patch. You need the following patch [1]
I'm going to send a pull request including this fix commit to Linus tomorrow. Takashi > > > Matthieu > > > > 3.2-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Takashi Iwai <[email protected]> > > > > commit 34f3c89fda4fba9fe689db22253ca8db2f5e6386 upstream. > > > > Replace mutex with rwsem for codec->shutdown protection so that > > concurrent accesses are allowed. > > > > Also add the protection to snd_usb_autosuspend() and > > snd_usb_autoresume(), too. > > > > Reported-by: Matthieu CASTET <[email protected]> > > Signed-off-by: Takashi Iwai <[email protected]> > > Signed-off-by: Ben Hutchings <[email protected]> > > --- > > sound/usb/card.c | 12 ++++++++---- > > sound/usb/mixer.c | 12 ++++++------ > > sound/usb/pcm.c | 12 ++++++------ > > sound/usb/usbaudio.h | 2 +- > > 4 files changed, 21 insertions(+), 17 deletions(-) > > > > [1] > > Takashi Iwai a écrit : > > At Tue, 13 Nov 2012 10:39:14 +0100, > > Jiri Slaby wrote: > >> On 11/13/2012 09:45 AM, Takashi Iwai wrote: > >>> At Tue, 13 Nov 2012 09:30:10 +0100, > >>> Jiri Slaby wrote: > >>>> On 11/13/2012 09:28 AM, Takashi Iwai wrote: > >>>>> At Tue, 13 Nov 2012 09:26:17 +0100, > >>>>> Jiri Slaby wrote: > >>>>>> Hello, > >>>>>> > >>>>>> I've just plugged+unplugged+plugged my USB audio card and the audio > >>>>>> subsystem got stuck: > >>>>> Which kernel? If it's older than 3.7-rc5, could you try 3.7-rc5? > >>>> Oh, forgot to mention: > >>>> 3.7.0-rc5-next-20121112_64+ > >>> Through a quick glance, one of mutex locks seems stuck. > >>> Just a blind short -- does the patch below cure the problem? > >> Yes, this helps. > >> > >> Adding a LOCKDEP splash _before_ applying the patch: > > > > Thanks, this helps much for understanding the cause. > > It's a new rwsem in the usb-audio driver that deadlocks. > > > > Although the previous patch fixes the deadlock it opens the race > > again. > > > > Could you try the patch below instead? The rwsem above doesn't have > > to be taken for the whole operation, but just needs to protect for > > turning on the flag. The patch below should suffice for protecting > > races but avoids the deadlock. > > > > > > Takashi > > > > --- > > diff --git a/sound/usb/card.c b/sound/usb/card.c > > index 282f0fc..dbf7999 100644 > > --- a/sound/usb/card.c > > +++ b/sound/usb/card.c > > @@ -559,9 +559,11 @@ static void snd_usb_audio_disconnect(struct usb_device > > *dev, > > return; > > > > card = chip->card; > > - mutex_lock(®ister_mutex); > > down_write(&chip->shutdown_rwsem); > > chip->shutdown = 1; > > + up_write(&chip->shutdown_rwsem); > > + > > + mutex_lock(®ister_mutex); > > chip->num_interfaces--; > > if (chip->num_interfaces <= 0) { > > snd_card_disconnect(card); > > @@ -582,11 +584,9 @@ static void snd_usb_audio_disconnect(struct usb_device > > *dev, > > snd_usb_mixer_disconnect(p); > > } > > usb_chip[chip->index] = NULL; > > - up_write(&chip->shutdown_rwsem); > > mutex_unlock(®ister_mutex); > > snd_card_free_when_closed(card); > > } else { > > - up_write(&chip->shutdown_rwsem); > > mutex_unlock(®ister_mutex); > > } > > } > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > > the body of a message to [email protected] > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
