[Pkg-alsa-devel] Bug#400268: Possible race condition on semaphores ?

[Vincent Fourmond]

Package: libasound2
Version: 1.0.13-1
Severity: normal


  Hello !

  I first would like to apologize, as this is the most vague bug report
I've ever sent. I hope it will tell something for you. 

  For the past few days, apparently deconnected with any software upgrade,
various sound applications using alsa hang. Upon inspection with GDB, they all
show a backtrace similar to the following:

#0  0x00002b4dcc6098f9 in semop () from /lib/libc.so.6
#1  0x00002aaaab31d6a0 in snd_pcm_dmix_open () from /usr/lib/libasound.so.2
#2  0x00002aaaab31e0a5 in _snd_pcm_dmix_open () from /usr/lib/libasound.so.2
#3  0x00002aaaab2f0ae8 in snd_pcm_free () from /usr/lib/libasound.so.2
#4  0x00002aaaab2f1096 in snd_pcm_free () from /usr/lib/libasound.so.2
#5  0x00002aaaab2f116a in snd_pcm_open_slave () from /usr/lib/libasound.so.2
#6  0x00002aaaab3267b1 in _snd_pcm_softvol_open () from /usr/lib/libasound.so.2
#7  0x00002aaaab2f0ae8 in snd_pcm_free () from /usr/lib/libasound.so.2
#8  0x00002aaaab2f11a7 in snd_pcm_open_slave () from /usr/lib/libasound.so.2
#9  0x00002aaaab30a207 in _snd_pcm_plug_open () from /usr/lib/libasound.so.2
#10 0x00002aaaab2f0ae8 in snd_pcm_free () from /usr/lib/libasound.so.2
#11 0x00002aaaab2f11a7 in snd_pcm_open_slave () from /usr/lib/libasound.so.2
#12 0x00002aaaab3245e9 in _snd_pcm_asym_open () from /usr/lib/libasound.so.2
#13 0x00002aaaab2f0ae8 in snd_pcm_free () from /usr/lib/libasound.so.2
#14 0x00002aaaab2f1096 in snd_pcm_free () from /usr/lib/libasound.so.2
#15 0x00002aaaab18b20a in alsa_free () from /usr/lib/xmms/Output/libALSA.so
[...]

  It looks like one program is taking the 'ownership' of the semaphore and
not giving it back, or so it seems.

  I tried removing all the programs linked to libasound (in root,
lsof | grep libasound gives nothing), removing all the sound modules
from the kernel and putting them back again, but it doesn't improve the
situation.

  If that helps somehow, here is some information from procfs :

vincent at tanyaivinco /proc/asound/card0/pcm0p/sub0 cat hw_params status sw_params 
closed
closed
closed

vincent at tanyaivinco /proc/asound/card0/pcm0p/sub0 cat info 
card: 0
device: 0
subdevice: 0
stream: PLAYBACK
id: Intel ICH
name: NVidia CK804
subname: subdevice #0
class: 0
subclass: 0
subdevices_count: 1
subdevices_avail: 1

vincent at tanyaivinco /proc/asound/card0/pcm0p/sub0 cat prealloc 
64

  OSS emulation works fine, and that's what keeps me listening to music.

  I'm ready to provide you with any additionnal information you should need.
I hope you'll have some ideas !

  Thanks for considering this report !

	Vincent Fourmond



-- System Information:
Debian Release: 4.0
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing')
Architecture: amd64 (x86_64)
Shell:  /bin/sh linked to /bin/dash
Kernel: Linux 2.6.18
Locale: LANG=en_GB, LC_CTYPE=en_GB (charmap=ISO-8859-1) (ignored: LC_ALL set to en_GB)

Versions of packages libasound2 depends on:
ii  libc6                        2.3.6.ds1-8 GNU C Library: Shared libraries

libasound2 recommends no packages.

-- no debconf information