atomic_add_return
if (atomic_add_return(1, &vblank->refcount) == 1) {
score = atomic_add_return(CONTEXT_SCORE_GUILTY, &ctx->ban_score);
#define atomic_add(i, v) atomic_add_return((i), (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))
#define atomic_add_negative(i, v) (atomic_add_return((i), (v)) < 0)
#define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0)