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pcm: Add LIBASOUND_THREAD_SAFE env variable check

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For making the debugging with any deadlocks by the newly introduced
thread-safety feature, add a check with LIBASOUND_THREAD_SAFE
environment variable.  When this variable is set to "0", alsa-lib PCM
forcibly disables the whole thread-safe pthread mutex calls.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2016-07-07 15:21:14 +02:00
parent 7a8a1d1552
commit c4b690278e
2 changed files with 20 additions and 2 deletions
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16
src/pcm/pcm.c
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@ -494,6 +494,13 @@ aren't thread-safe, and application needs to call them carefully when they
are called from multiple threads. In general, all the functions that are
often called during streaming are covered as thread-safe.
This thread-safe behavior can be disabled also by passing 0 to the environment
variable LIBASOUND_THREAD_SAFE, e.g.
\code
LIBASOUND_THREAD_SAFE=0 aplay foo.wav
\endcode
for making the debugging easier.
\section pcm_dev_names PCM naming conventions
The ALSA library uses a generic string representation for names of devices.
@ -2536,6 +2543,15 @@ int snd_pcm_new(snd_pcm_t **pcmp, snd_pcm_type_t type, const char *name,
INIT_LIST_HEAD(&pcm->async_handlers);
#ifdef THREAD_SAFE_API
pthread_mutex_init(&pcm->lock, NULL);
{
static int default_thread_safe = -1;
if (default_thread_safe < 0) {
char *p = getenv("LIBASOUND_THREAD_SAFE");
default_thread_safe = !p || *p != '0';
}
if (!default_thread_safe)
pcm->thread_safe = -1; /* force to disable */
}
#endif
*pcmp = pcm;
return 0;

6
src/pcm/pcm_local.h
View file

@ -1087,11 +1087,13 @@ static inline void sw_set_period_event(snd_pcm_sw_params_t *params, int val)
#ifdef THREAD_SAFE_API
static inline void __snd_pcm_lock(snd_pcm_t *pcm)
{
pthread_mutex_lock(&pcm->lock);
if (pcm->thread_safe >= 0)
pthread_mutex_lock(&pcm->lock);
}
static inline void __snd_pcm_unlock(snd_pcm_t *pcm)
{
pthread_mutex_unlock(&pcm->lock);
if (pcm->thread_safe >= 0)
pthread_mutex_unlock(&pcm->lock);
}
static inline void snd_pcm_lock(snd_pcm_t *pcm)
{