qdisc_match_from_root
q = qdisc_match_from_root(root, TC_H_MAJ(tcm->tcm_parent));
q = qdisc_match_from_root(rtnl_dereference(dev->qdisc), handle);
q = qdisc_match_from_root(
q = qdisc_match_from_root(rcu_dereference(dev->qdisc), handle);
q = qdisc_match_from_root(rcu_dereference(nq->qdisc_sleeping),