[alsa-devel] [alsa-lib] Query regarding snd_config_update_free_global() and threads etc.

[Jaroslav Kysela]

On Mon, 23 Aug 2010, Colin Guthrie wrote:

> Hi there,
>
> I've got a (hopefully quick) query about snd_config_update_free_global()
> and it's general thread safetyness.
>
>
> I'm currently going insane on this bug:
> https://bugs.kde.org/show_bug.cgi?id=232068
> which revolves around a bug manifested in snd_pcm_close() (or rather
> snd_pcm_ioplug_close()) when dealing with the ALSA->PulseAudio plugin.
>
>> From what I can gather, this problem is related to a KDE module that is
> loaded into the library in question which does some alsa probing and
> ultimately calls snd_config_update_free_global() several times. The
> library itself then goes on to use GStreamer to do actual audio output.
> The crash then manifests itself prior to any sound actually being output.
>
> I can reliably reproduce the machine on two machines (I don't have many
> at my disposal), but cannot reproduce on a third. The two I can
> reproduce it on are two and four core intel duo's. The one I cannot
> reproduce on is an older, single core machine. I am leaning towards some
> kind of thread safety issue.
>
>
> In searching for similar problems, I found several references to similar
> crashes attributed to snd_dlobj_cache_cleanup() perhaps not being thread
> safe.

I tried to work on snd_dlobj_cache issues. Please, could you test this 
patch?

http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=91c9c8f1b85e69b4bdc94a777d2767c4906c3f47

 					Thanks,
 						Jaroslav

-----
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.