At Wed, 30 Jan 2013 16:22:15 +0100, Jerome Forissier wrote:
This is a set of two patches to fix thread safety issues I found when running a video application over ALSA. The application uses LibVLC to play several videos simultaneously. LibVLC calls snd_pcm_open() and snd_device_name_hint() from multiple threads, without locking--which is allowed according to http://www.alsa-project.org/main/index.php/SMP_Design.
The fix for snd_pcm_direct_parse_open_conf() looks good. I'm going to apply this now.
snd_device_name_hint() should use snd_config_update_r() and pass the local config space to others instead of snd_config.
thanks,
Takashi
Without these patches, I would get random error messages like:
ALSA lib confmisc.c:768:(parse_card) cannot find card '$CARD' ALSA lib conf.c:4184:(_snd_config_evaluate) function snd_func_card_driver returned error: No such device ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:4184:(_snd_config_evaluate) function snd_func_concat returned error: No such device ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:4184:(_snd_config_evaluate) function snd_func_refer returned error: No such device ALSA lib conf.c:4663:(snd_config_expand) Evaluate error: No such device
Jerome Forissier (2): Make snd_device_name_hint() thread-safe by locking a mutex snd_pcm_direct_parse_open_conf(): use thread-safe getgrnam_r()
src/control/namehint.c | 31 +++++++++++++++++++++++++++++++ src/pcm/pcm_direct.c | 15 +++++++++++---- 2 files changed, 42 insertions(+), 4 deletions(-)
-- 1.8.1.2
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