sdl_unlocksurface(3) - Linux man page
Name
SDL_UnlockSurface - Unlocks a previously locked surface.Synopsis
#include "SDL.h"
void SDL_UnlockSurface(SDL_Surface *surface);
Description
Surfaces that were previously locked using SDL_LockSurface must be unlocked with SDL_UnlockSurface. Surfaces should be unlocked as soon as possible.
It should be noted that since 1.1.8, surface locks are recursive. See SDL_LockSurface.
See Also
SDL_LockSurface