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authorStephen Hemminger <shemminger@osdl.org>2005-05-26 12:53:49 -0700
committerDavid S. Miller <davem@davemloft.net>2005-05-26 12:53:49 -0700
commit0afb51e72855971dba83b3c6b70c547c2d1161fd (patch)
tree8f0e3cd40e381f4dd9de2e7431490ae8cbbf6498
parentcdbbde14cb55dd10771ce79154f787322d88411b (diff)
downloadop-kernel-dev-0afb51e72855971dba83b3c6b70c547c2d1161fd.zip
op-kernel-dev-0afb51e72855971dba83b3c6b70c547c2d1161fd.tar.gz
[PKT_SCHED]: netem: reinsert for duplication
Handle duplication of packets in netem by re-inserting at top of qdisc tree. This avoid problems with qlen accounting with nested qdisc. This recursion requires no additional locking but will potentially increase stack depth. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/sch_netem.c53
1 files changed, 29 insertions, 24 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index e0c9fbe..5c0f0c2 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -203,42 +203,47 @@ static int netem_run(struct Qdisc *sch)
return 0;
}
+/*
+ * Insert one skb into qdisc.
+ * Note: parent depends on return value to account for queue length.
+ * NET_XMIT_DROP: queue length didn't change.
+ * NET_XMIT_SUCCESS: one skb was queued.
+ */
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;
+ int count = 1;
pr_debug("netem_enqueue skb=%p\n", skb);
+ /* Random duplication */
+ if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
+ ++count;
+
/* Random packet drop 0 => none, ~0 => all */
- if (q->loss && q->loss >= get_crandom(&q->loss_cor)) {
- pr_debug("netem_enqueue: random loss\n");
+ if (q->loss && q->loss >= get_crandom(&q->loss_cor))
+ --count;
+
+ if (count == 0) {
sch->qstats.drops++;
kfree_skb(skb);
- return 0; /* lie about loss so TCP doesn't know */
+ return NET_XMIT_DROP;
}
- /* Random duplication */
- 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++;
-
- sch->q.qlen++;
- sch->bstats.bytes += skb2->len;
- sch->bstats.packets++;
- } else
- sch->qstats.drops++;
+ /*
+ * If we need to duplicate packet, then re-insert at top of the
+ * qdisc tree, since parent queuer expects that only one
+ * skb will be queued.
+ */
+ if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
+ struct Qdisc *rootq = sch->dev->qdisc;
+ u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
+ q->duplicate = 0;
+
+ rootq->enqueue(skb2, rootq);
+ q->duplicate = dupsave;
}
/* If doing simple delay then gap == 0 so all packets
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