avoid accessing mutex memory after atomic unlock

this change is needed to fix a race condition and ensure that it's
possible to unlock and destroy or unmap the mutex as soon as
pthread_mutex_lock succeeds. POSIX explicitly gives such an example in
the rationale and requires an implementation to allow such usage.

1 files changed, 1 insertions, 13 deletions

diff --git a/src/thread/pthread_mutex_lock.c b/src/thread/pthread_mutex_lock.c
index 99c15bd8..2b4f3a73 100644
--- a/src/thread/pthread_mutex_lock.c
+++ b/src/thread/pthread_mutex_lock.c
@@ -2,17 +2,5 @@
 
 int pthread_mutex_lock(pthread_mutex_t *m)
 {
-	int r;
-
-	if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, EBUSY))
-		return 0;
-
-	while ((r=pthread_mutex_trylock(m)) == EBUSY) {
-		if (!(r=m->_m_lock) || (r&0x40000000)) continue;
-		if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
-		 && (r&0x1fffffff) == pthread_self()->tid)
-			return EDEADLK;
-		__wait(&m->_m_lock, &m->_m_waiters, r, 0);
-	}
-	return r;
+	return pthread_mutex_timedlock(m, 0);
 }