do_prlimit
ret = do_prlimit(current, resource, NULL, &value);
return do_prlimit(current, resource, &r, NULL);
ret = do_prlimit(current, resource, NULL, &r);
ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
return do_prlimit(current, resource, &new_rlim, NULL);