The commit 
520ac30f4551 ("net_sched: drop packets after root qdisc lock
is released) made a big change of tc for performance. There are two points
left in sch_prio and sch_qfq which are not changed with that commit. Now
enhance them now with __qdisc_drop.
Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
                if (ret & __NET_XMIT_BYPASS)
                        qdisc_qstats_drop(sch);
-               kfree_skb(skb);
+               __qdisc_drop(skb, to_free);
                return ret;
        }
 #endif
 
        if (cl == NULL) {
                if (err & __NET_XMIT_BYPASS)
                        qdisc_qstats_drop(sch);
-               kfree_skb(skb);
+               __qdisc_drop(skb, to_free);
                return err;
        }
        pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);