tg_nop
return walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
extern int tg_nop(struct task_group *tg, void *data);