[PKT_SCHED]: netetm: adjust parent qlen when duplicating

Fix qlen underrun when doing duplication with netem. If netem is used
as leaf discipline, then the parent needs to be tweaked when packets
are duplicated.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 16 insertions, 5 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 4323a74eea30..07977f8f2679 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1289,6 +1289,7 @@ static int __init pktsched_init(void)
 
 subsys_initcall(pktsched_init);
 
+EXPORT_SYMBOL(qdisc_lookup);
 EXPORT_SYMBOL(qdisc_get_rtab);
 EXPORT_SYMBOL(qdisc_put_rtab);
 EXPORT_SYMBOL(register_qdisc);
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 864b8d353ffa..e0c9fbe73b15 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -206,7 +206,6 @@ static int netem_run(struct Qdisc *sch)
 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
         struct netem_sched_data *q = qdisc_priv(sch);
-        struct sk_buff *skb2;
         int ret;
 
         pr_debug("netem_enqueue skb=%p\n", skb);
@@ -220,11 +219,21 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
         }
 
         /* Random duplication */
-        if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)
-            && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
-                pr_debug("netem_enqueue: dup %p\n", skb2);
+        if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) {
+                struct sk_buff *skb2;
+
+                skb2 = skb_clone(skb, GFP_ATOMIC);
+                if (skb2 && netem_delay(sch, skb2) == NET_XMIT_SUCCESS) {
+                        struct Qdisc *qp;
+
+                        /* Since one packet can generate two packets in the
+                         * queue, the parent's qlen accounting gets confused,
+                         * so fix it.
+                         */
+                        qp = qdisc_lookup(sch->dev, TC_H_MAJ(sch->parent));
+                        if (qp)
+                                qp->q.qlen++;
 
-                if (netem_delay(sch, skb2)) {
                         sch->q.qlen++;
                         sch->bstats.bytes += skb2->len;
                         sch->bstats.packets++;
@@ -253,6 +262,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
         } else
                 sch->qstats.drops++;
 
+        pr_debug("netem: enqueue ret %d\n", ret);
         return ret;
 }