sched: remove qdisc arg from __qdisc_dequeue_head

Moves qdisc stat accouting to qdisc_dequeue_head.

The only direct caller of the __qdisc_dequeue_head version open-codes
this now.

This allows us to later use __qdisc_dequeue_head as a replacement
of __skb_dequeue() (which operates on sk_buff_head list).
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -614,11 +614,17 @@ static inline int qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch)
 	return __qdisc_enqueue_tail(skb, sch, &sch->q);
 }
 
-static inline struct sk_buff *__qdisc_dequeue_head(struct Qdisc *sch,
-						   struct sk_buff_head *list)
+static inline struct sk_buff *__qdisc_dequeue_head(struct sk_buff_head *list)
 {
 	struct sk_buff *skb = __skb_dequeue(list);
 
+	return skb;
+}
+
+static inline struct sk_buff *qdisc_dequeue_head(struct Qdisc *sch)
+{
+	struct sk_buff *skb = __qdisc_dequeue_head(&sch->q);
+
 	if (likely(skb != NULL)) {
 		qdisc_qstats_backlog_dec(sch, skb);
 		qdisc_bstats_update(sch, skb);
@@ -627,11 +633,6 @@ static inline struct sk_buff *__qdisc_dequeue_head(struct Qdisc *sch,
 	return skb;
 }
 
-static inline struct sk_buff *qdisc_dequeue_head(struct Qdisc *sch)
-{
-	return __qdisc_dequeue_head(sch, &sch->q);
-}
-
 /* Instead of calling kfree_skb() while root qdisc lock is held,
  * queue the skb for future freeing at end of __dev_xmit_skb()
  */

net/sched/sch_generic.c

@@ -506,7 +506,12 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 
 	if (likely(band >= 0)) {
 		struct sk_buff_head *list = band2list(priv, band);
-		struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list);
+		struct sk_buff *skb = __qdisc_dequeue_head(list);
+
+		if (likely(skb != NULL)) {
+			qdisc_qstats_backlog_dec(qdisc, skb);
+			qdisc_bstats_update(qdisc, skb);
+		}
 
 		qdisc->q.qlen--;
 		if (skb_queue_empty(list))