SDL_LockAudio (3) - Linux Manuals
SDL_LockAudio: Lock out the callback function
NAME
SDL_LockAudio - Lock out the callback functionSYNOPSIS
#include "SDL.h"
DESCRIPTION
The lock manipulated by these functions protects the callback function. During a LockAudio period, you can be guaranteed that the callback function is not running. Do not call these from the callback function or you will cause deadlock.
SEE ALSO
SDL_OpenAudio