pkt_sched: Use qdisc->ops->peek() instead of ->dequeue() & ->requeue()

Use qdisc->ops->peek() instead of ->dequeue() & ->requeue() pair.
After this patch the only remaining user of qdisc->ops->requeue() is
netem_enqueue(). Based on ideas of Herbert Xu, Patrick McHardy and
David S. Miller.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 8 deletions

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 2898d9dc31eb..74fbdb52baed 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -283,25 +283,22 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
         if (sch->flags & TCQ_F_THROTTLED)
                 return NULL;
 
-        skb = q->qdisc->dequeue(q->qdisc);
+        skb = q->qdisc->ops->peek(q->qdisc);
         if (skb) {
                 const struct netem_skb_cb *cb = netem_skb_cb(skb);
                 psched_time_t now = psched_get_time();
 
                 /* if more time remaining? */
                 if (cb->time_to_send <= now) {
+                        skb = q->qdisc->dequeue(q->qdisc);
+                        if (!skb)
+                                return NULL;
+
                         pr_debug("netem_dequeue: return skb=%p\n", skb);
                         sch->q.qlen--;
                         return skb;
                 }
 
-                if (unlikely(q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS)) {
-                        qdisc_tree_decrease_qlen(q->qdisc, 1);
-                        sch->qstats.drops++;
-                        printk(KERN_ERR "netem: %s could not requeue\n",
-                               q->qdisc->ops->id);
-                }
-
                 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
         }