net_sched: sch_fq: do not call fq_peek() twice per packet

This refactors the code to not call fq_peek() from fq_dequeue_head()
since the caller can provide the skb.

Also rename fq_dequeue_head() to fq_dequeue_skb() because 'head' is
a bit vague, given the skb could come from t_root rb-tree.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 53ec47f..567df8f 100644 (file)
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -384,19 +384,17 @@ static void fq_erase_head(struct Qdisc *sch, struct fq_flow *flow,
        }
 }
 
-/* remove one skb from head of flow queue */
-static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, struct fq_flow *flow)
+/* Remove one skb from flow queue.
+ * This skb must be the return value of prior fq_peek().
+ */
+static void fq_dequeue_skb(struct Qdisc *sch, struct fq_flow *flow,
+                          struct sk_buff *skb)
 {
-       struct sk_buff *skb = fq_peek(flow);
-
-       if (skb) {
-               fq_erase_head(sch, flow, skb);
-               skb_mark_not_on_list(skb);
-               flow->qlen--;
-               qdisc_qstats_backlog_dec(sch, skb);
-               sch->q.qlen--;
-       }
-       return skb;
+       fq_erase_head(sch, flow, skb);
+       skb_mark_not_on_list(skb);
+       flow->qlen--;
+       qdisc_qstats_backlog_dec(sch, skb);
+       sch->q.qlen--;
 }
 
 static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
@@ -508,9 +506,11 @@ static struct sk_buff *fq_dequeue(struct Qdisc *sch)
        if (!sch->q.qlen)
                return NULL;
 
-       skb = fq_dequeue_head(sch, &q->internal);
-       if (skb)
+       skb = fq_peek(&q->internal);
+       if (unlikely(skb)) {
+               fq_dequeue_skb(sch, &q->internal, skb);
                goto out;
+       }
 
        now = ktime_get_ns();
        fq_check_throttled(q, now);
@@ -550,10 +550,8 @@ begin:
                        INET_ECN_set_ce(skb);
                        q->stat_ce_mark++;
                }
-       }
-
-       skb = fq_dequeue_head(sch, f);
-       if (!skb) {
+               fq_dequeue_skb(sch, f, skb);
+       } else {
                head->first = f->next;
                /* force a pass through old_flows to prevent starvation */
                if ((head == &q->new_flows) && q->old_flows.first) {