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, 7 insertions, 4 deletions

diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index f9eac0818d18..2ee0c1a8efa9 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -480,11 +480,14 @@ static void sch_atm_dequeue(unsigned long data)
                  * If traffic is properly shaped, this won't generate nasty
                  * little bursts. Otherwise, it may ... (but that's okay)
                  */
-                while ((skb = flow->q->dequeue(flow->q))) {
-                        if (!atm_may_send(flow->vcc, skb->truesize)) {
-                                (void)flow->q->ops->requeue(skb, flow->q);
+                while ((skb = flow->q->ops->peek(flow->q))) {
+                        if (!atm_may_send(flow->vcc, skb->truesize))
                                 break;
-                        }
+
+                        skb = flow->q->dequeue(flow->q);
+                        if (unlikely(!skb))
+                                break;
+
                         pr_debug("atm_tc_dequeue: sending on class %p\n", flow);
                         /* remove any LL header somebody else has attached */
                         skb_pull(skb, skb_network_offset(skb));