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config file processing: rewrite the locking - use one recursive mutex

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Avoid configuration file processing races when multiple threads call
the *open() functions together (for example using alsaloop with
multiple -T jobs can reproduce this issue).

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2010-10-11 10:34:12 +02:00
parent c049d48407
commit c6a81e21c0
1 changed files with 39 additions and 20 deletions
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59
src/conf.c
View file

@ -425,6 +425,11 @@ beginning:</P>
#ifndef DOC_HIDDEN
#ifdef HAVE_LIBPTHREAD
static pthread_mutex_t snd_config_update_mutex =
PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
#endif
struct _snd_config {
char *id;
snd_config_type_t type;
@ -464,6 +469,25 @@ typedef struct {
int ch;
} input_t;
#ifdef HAVE_LIBPTHREAD
static inline void snd_config_lock(void)
{
pthread_mutex_lock(&snd_config_update_mutex);
}
static inline void snd_config_unlock(void)
{
pthread_mutex_unlock(&snd_config_update_mutex);
}
#else
static inline void snd_config_lock(void) { }
static inline void snd_config_unlock(void) { }
#endif
static int safe_strtoll(const char *str, long long *val)
{
long long v;
@ -3318,6 +3342,7 @@ static int snd_config_hooks(snd_config_t *config, snd_config_t *private_data)
if ((err = snd_config_search(config, "@hooks", &n)) < 0)
return 0;
snd_config_lock();
snd_config_remove(n);
do {
hit = 0;
@ -3334,7 +3359,7 @@ static int snd_config_hooks(snd_config_t *config, snd_config_t *private_data)
if (i == idx) {
err = snd_config_hooks_call(config, n, private_data);
if (err < 0)
return err;
goto _err;
idx++;
hit = 1;
}
@ -3343,6 +3368,7 @@ static int snd_config_hooks(snd_config_t *config, snd_config_t *private_data)
err = 0;
_err:
snd_config_delete(n);
snd_config_unlock();
return err;
}
@ -3692,10 +3718,6 @@ int snd_config_update_r(snd_config_t **_top, snd_config_update_t **_update, cons
return 1;
}
#ifdef HAVE_LIBPTHREAD
static pthread_mutex_t snd_config_update_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
/**
* \brief Updates #snd_config by rereading the global configuration files (if needed).
* \return 0 if #snd_config was up to date, 1 if #snd_config was
@ -3716,13 +3738,9 @@ int snd_config_update(void)
{
int err;
#ifdef HAVE_LIBPTHREAD
pthread_mutex_lock(&snd_config_update_mutex);
#endif
snd_config_lock();
err = snd_config_update_r(&snd_config, &snd_config_global_update, NULL);
#ifdef HAVE_LIBPTHREAD
pthread_mutex_unlock(&snd_config_update_mutex);
#endif
snd_config_unlock();
return err;
}
@ -3755,18 +3773,14 @@ int snd_config_update_free(snd_config_update_t *update)
*/
int snd_config_update_free_global(void)
{
#ifdef HAVE_LIBPTHREAD
pthread_mutex_lock(&snd_config_update_mutex);
#endif
snd_config_lock();
if (snd_config)
snd_config_delete(snd_config);
snd_config = NULL;
if (snd_config_global_update)
snd_config_update_free(snd_config_global_update);
snd_config_global_update = NULL;
#ifdef HAVE_LIBPTHREAD
pthread_mutex_unlock(&snd_config_update_mutex);
#endif
snd_config_unlock();
/* FIXME: better to place this in another place... */
snd_dlobj_cache_cleanup();
@ -4657,7 +4671,7 @@ int snd_config_expand(snd_config_t *config, snd_config_t *root, const char *args
snd_config_delete(subs);
return err;
}
/**
* \brief Searches for a definition in a configuration tree, using
* aliases and expanding hooks and arguments.
@ -4707,10 +4721,15 @@ int snd_config_search_definition(snd_config_t *config,
* if key contains dot (.), the implicit base is ignored
* and the key starts from root given by the 'config' parameter
*/
snd_config_lock();
err = snd_config_search_alias_hooks(config, strchr(key, '.') ? NULL : base, key, &conf);
if (err < 0)
if (err < 0) {
snd_config_unlock();
return err;
return snd_config_expand(conf, config, args, NULL, result);
}
err = snd_config_expand(conf, config, args, NULL, result);
snd_config_unlock();
return err;
}
#ifndef DOC_HIDDEN