coreaudio: Don't crash on shutdown in a race condition. Fixed #6159.
diff --git a/src/audio/coreaudio/SDL_coreaudio.m b/src/audio/coreaudio/SDL_coreaudio.m
index 4d35756..7caa3f4 100644
--- a/src/audio/coreaudio/SDL_coreaudio.m
+++ b/src/audio/coreaudio/SDL_coreaudio.m
@@ -523,8 +523,16 @@ outputCallback(void *inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffe
{
SDL_AudioDevice *this = (SDL_AudioDevice *) inUserData;
+ /* This flag is set before this->mixer_lock is destroyed during
+ shutdown, so check it before grabbing the mutex, and then check it
+ again _after_ in case we blocked waiting on the lock. */
+ if (SDL_AtomicGet(&this->shutdown)) {
+ return; /* don't do anything, since we don't even want to enqueue this buffer again. */
+ }
+
SDL_LockMutex(this->mixer_lock);
+ /* !!! FIXME: why do we have this->hidden->shutdown when this->shutdown exists? */
if (SDL_AtomicGet(&this->hidden->shutdown)) {
SDL_UnlockMutex(this->mixer_lock);
return; /* don't do anything, since we don't even want to enqueue this buffer again. */