net: sched: implement qstat helper routines

This adds helpers to manipulate qstats logic and replaces locations
that touch the counters directly. This simplifies future patches
to push qstats onto per cpu counters.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 105cf55..9270e1b 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -164,8 +164,8 @@
 	q->backlogs[idx] -= len;
 	kfree_skb(skb);
 	sch->q.qlen--;
-	sch->qstats.drops++;
-	sch->qstats.backlog -= len;
+	qdisc_qstats_drop(sch);
+	qdisc_qstats_backlog_dec(sch, skb);
 	flow->dropped++;
 	return idx;
 }
@@ -180,7 +180,7 @@
 	idx = fq_codel_classify(skb, sch, &ret);
 	if (idx == 0) {
 		if (ret & __NET_XMIT_BYPASS)
-			sch->qstats.drops++;
+			qdisc_qstats_drop(sch);
 		kfree_skb(skb);
 		return ret;
 	}
@@ -190,7 +190,7 @@
 	flow = &q->flows[idx];
 	flow_queue_add(flow, skb);
 	q->backlogs[idx] += qdisc_pkt_len(skb);
-	sch->qstats.backlog += qdisc_pkt_len(skb);
+	qdisc_qstats_backlog_inc(sch, skb);
 
 	if (list_empty(&flow->flowchain)) {
 		list_add_tail(&flow->flowchain, &q->new_flows);