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.
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(-)