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mutex: Switch the POSIX backend to PTHREAD_MUTEX_RECURSIVE 

The code for recursive mutexes triggered Undefined Behavior
and crash as pthread_equal(3) was not used in a portable way.
On the first call of mutex_lock() pthread_equal() was called with
a pthread_t of value -1 which is invalid.

Passing a non valid thread ID to pthread_equal is undefined.

Switch the backend to native interface for POSIX recursive
mutexes with PTHREAD_MUTEX_RECURSIVE and simplify the code.

Detected on NetBSD/amd64 9.99.46.

Signed-off-by: Marvin Scholz <epirat07@gmail.com>
This commit is contained in:
Kamil Rytarowski 2020-02-13 16:23:21 +01:00 committed by Marvin Scholz
parent 137974c5ed
commit bc2d0d8c41
1 changed files with 9 additions and 38 deletions
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47
src/util/mutex.c
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@ -68,18 +68,16 @@ static int _mutex_destroy(MUTEX_IMPL *p)
#elif defined(HAVE_PTHREAD_H)
typedef struct {
int lock_count;
pthread_t owner;
pthread_mutex_t mutex;
} MUTEX_IMPL;
typedef pthread_mutex_t MUTEX_IMPL;
static int _mutex_init(MUTEX_IMPL *p)
{
p->owner = (pthread_t)-1;
p->lock_count = 0;
pthread_mutexattr_t attr;
if (pthread_mutex_init(&p->mutex, NULL)) {
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
if (pthread_mutex_init(p, &attr)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_init() failed !\n");
return -1;
}
@ -89,40 +87,17 @@ static int _mutex_init(MUTEX_IMPL *p)
static int _mutex_lock(MUTEX_IMPL *p)
{
if (pthread_equal(p->owner, pthread_self())) {
/* recursive lock */
p->lock_count++;
return 0;
}
if (pthread_mutex_lock(&p->mutex)) {
if (pthread_mutex_lock(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_lock() failed !\n");
return -1;
}
p->owner = pthread_self();
p->lock_count = 1;
return 0;
}
static int _mutex_unlock(MUTEX_IMPL *p)
{
if (!pthread_equal(p->owner, pthread_self())) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "bd_mutex_unlock(): not owner !\n");
return -1;
}
p->lock_count--;
if (p->lock_count > 0) {
return 0;
}
/* unlock */
p->owner = (pthread_t)-1;
if (pthread_mutex_unlock(&p->mutex)) {
if (pthread_mutex_unlock(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_unlock() failed !\n");
return -1;
}
@ -132,10 +107,7 @@ static int _mutex_unlock(MUTEX_IMPL *p)
static int _mutex_destroy(MUTEX_IMPL *p)
{
_mutex_lock(p);
_mutex_unlock(p);
if (pthread_mutex_destroy(&p->mutex)) {
if (pthread_mutex_destroy(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_destroy() failed !\n");
return -1;
}
@ -193,4 +165,3 @@ int bd_mutex_destroy(BD_MUTEX *p)
X_FREE(p->impl);
return 0;
}