1. 06 Dec, 2012 38 commits
  2. 16 Nov, 2012 2 commits
    • Ben Hutchings's avatar
      Linux 3.2.34 · 155e0541
      Ben Hutchings authored
      155e0541
    • Takashi Iwai's avatar
      ALSA: usb-audio: Fix mutex deadlock at disconnection · c585c4e1
      Takashi Iwai authored
      commit 10e44239 upstream.
      
      The recent change for USB-audio disconnection race fixes introduced a
      mutex deadlock again.  There is a circular dependency between
      chip->shutdown_rwsem and pcm->open_mutex, depicted like below, when a
      device is opened during the disconnection operation:
      
      A. snd_usb_audio_disconnect() ->
           card.c::register_mutex ->
             chip->shutdown_rwsem (write) ->
               snd_card_disconnect() ->
                 pcm.c::register_mutex ->
                   pcm->open_mutex
      
      B. snd_pcm_open() ->
           pcm->open_mutex ->
             snd_usb_pcm_open() ->
               chip->shutdown_rwsem (read)
      
      Since the chip->shutdown_rwsem protection in the case A is required
      only for turning on the chip->shutdown flag and it doesn't have to be
      taken for the whole operation, we can reduce its window in
      snd_usb_audio_disconnect().
      Reported-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c585c4e1