pkt_sched: Use qdisc->ops->peek() instead of ->dequeue() & ->requeue()
Jarek Poplawski [Fri, 31 Oct 2008 07:46:19 +0000 (00:46 -0700)]
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>

net/sched/sch_atm.c
net/sched/sch_hfsc.c
net/sched/sch_netem.c
net/sched/sch_tbf.c

index f9eac08..2ee0c1a 100644 (file)
@@ -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));
index c1e77da..ddfc408 100644 (file)
@@ -880,28 +880,20 @@ set_passive(struct hfsc_class *cl)
         */
 }
 
-/*
- * hack to get length of first packet in queue.
- */
 static unsigned int
 qdisc_peek_len(struct Qdisc *sch)
 {
        struct sk_buff *skb;
        unsigned int len;
 
-       skb = sch->dequeue(sch);
+       skb = sch->ops->peek(sch);
        if (skb == NULL) {
                if (net_ratelimit())
                        printk("qdisc_peek_len: non work-conserving qdisc ?\n");
                return 0;
        }
        len = qdisc_pkt_len(skb);
-       if (unlikely(sch->ops->requeue(skb, sch) != NET_XMIT_SUCCESS)) {
-               if (net_ratelimit())
-                       printk("qdisc_peek_len: failed to requeue\n");
-               qdisc_tree_decrease_qlen(sch, 1);
-               return 0;
-       }
+
        return len;
 }
 
index 2898d9d..74fbdb5 100644 (file)
@@ -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);
        }
 
index 94c6159..61fdc77 100644 (file)
@@ -169,7 +169,7 @@ static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
        struct tbf_sched_data *q = qdisc_priv(sch);
        struct sk_buff *skb;
 
-       skb = q->qdisc->dequeue(q->qdisc);
+       skb = q->qdisc->ops->peek(q->qdisc);
 
        if (skb) {
                psched_time_t now;
@@ -192,6 +192,10 @@ static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
                toks -= L2T(q, len);
 
                if ((toks|ptoks) >= 0) {
+                       skb = q->qdisc->dequeue(q->qdisc);
+                       if (unlikely(!skb))
+                               return NULL;
+
                        q->t_c = now;
                        q->tokens = toks;
                        q->ptokens = ptoks;
@@ -214,12 +218,6 @@ static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
                   (cf. CSZ, HPFQ, HFSC)
                 */
 
-               if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
-                       /* When requeue fails skb is dropped */
-                       qdisc_tree_decrease_qlen(q->qdisc, 1);
-                       sch->qstats.drops++;
-               }
-
                sch->qstats.overlimits++;
        }
        return NULL;