diff --git a/include/SDL_mutex.h b/include/SDL_mutex.h index fffc0b8e5..fa826888c 100644 --- a/include/SDL_mutex.h +++ b/include/SDL_mutex.h @@ -66,7 +66,10 @@ extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void); #define SDL_LockMutex(m) SDL_mutexP(m) extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex); -/* Unlock the mutex (Returns 0, or -1 on error) */ +/* Unlock the mutex (Returns 0, or -1 on error) + It is an error to unlock a mutex that has not been locked by + the current thread, and doing so results in undefined behavior. + */ #define SDL_UnlockMutex(m) SDL_mutexV(m) extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex);