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

Jaroslav Kysela perex at perex.cz
Mon Aug 23 17:13:15 CEST 2010

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 



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

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