Fixed bug 3258 - SDL_TryLockMutex blocks for pthreads with FAKE_RECURSIVE_MUTEX

Ian Abbott

I just spotted what I think is a bug in "src/thread/pthread/SDL_sysmutex.c" in the SDL_TryLockMutex function when FAKE_RECURSIVE_MUTEX is defined (for an implementation of Pthreads with no recursive mutex support).  It calls pthread_mutex_lock instead of pthread_mutex_trylock, so it will block until the mutex is available instead of returning SDL_MUTEX_TIMEDOUT if it cannot lock the mutex immediately.

src/thread/pthread/SDL_sysmutex.c

@@ -134,7 +134,7 @@ SDL_TryLockMutex(SDL_mutex * mutex)
          We set the locking thread id after we obtain the lock
          so unlocks from other threads will fail.
          */
-        if (pthread_mutex_lock(&mutex->id) == 0) {
+        if (pthread_mutex_trylock(&mutex->id) == 0) {
             mutex->owner = this_thread;
             mutex->recursive = 0;
         } else if (errno == EBUSY) {