cmpxchg
prev = cmpxchg(lock, old, new);
prev = cmpxchg(lock, old, new);
prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
prev = cmpxchg(lock, old, new);
#define cmpxchg_relaxed(...) cmpxchg(__VA_ARGS__)
cmpxchg(&array->base.error, PENDING_ERROR, error);
cmpxchg(&array->base.error, PENDING_ERROR, 0);
last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);