patches.codel/netem-add-ECN-capability.patch

From 7c960a26b2c7abeb31df195d81453f08bda401f1 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 30 Apr 2012 23:11:05 +0000
Subject: [PATCH] netem: add ECN capability

commit e4ae004b84b315dd4b762e474f97403eac70f76a upstream.

Add ECN (Explicit Congestion Notification) marking capability to netem

tc qdisc add dev eth0 root netem drop 0.5 ecn

Instead of dropping packets, try to ECN mark them.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

---
 include/linux/pkt_sched.h |    1 +
 net/sched/sch_netem.c     |   18 +++++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

--- a/include/linux/pkt_sched.h
+++ b/include/linux/pkt_sched.h
@@ -509,6 +509,7 @@ enum {
 	TCA_NETEM_CORRUPT,
 	TCA_NETEM_LOSS,
 	TCA_NETEM_RATE,
+	TCA_NETEM_ECN,
 	__TCA_NETEM_MAX,
 };
 
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -26,6 +26,7 @@
 
 #include <net/netlink.h>
 #include <net/pkt_sched.h>
+#include <net/inet_ecn.h>
 
 #define VERSION "1.3"
 
@@ -78,6 +79,7 @@ struct netem_sched_data {
 	psched_tdiff_t jitter;
 
 	u32 loss;
+	u32 ecn;
 	u32 limit;
 	u32 counter;
 	u32 gap;
@@ -366,9 +368,12 @@ static int netem_enqueue(struct sk_buff
 		++count;
 
 	/* Drop packet? */
-	if (loss_event(q))
-		--count;
-
+	if (loss_event(q)) {
+		if (q->ecn && INET_ECN_set_ce(skb))
+			sch->qstats.drops++; /* mark packet */
+		else
+			--count;
+	}
 	if (count == 0) {
 		sch->qstats.drops++;
 		kfree_skb(skb);
@@ -692,6 +697,7 @@ static const struct nla_policy netem_pol
 	[TCA_NETEM_CORRUPT]	= { .len = sizeof(struct tc_netem_corrupt) },
 	[TCA_NETEM_RATE]	= { .len = sizeof(struct tc_netem_rate) },
 	[TCA_NETEM_LOSS]	= { .type = NLA_NESTED },
+	[TCA_NETEM_ECN]		= { .type = NLA_U32 },
 };
 
 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
@@ -762,6 +768,9 @@ static int netem_change(struct Qdisc *sc
 	if (tb[TCA_NETEM_RATE])
 		get_rate(sch, tb[TCA_NETEM_RATE]);
 
+	if (tb[TCA_NETEM_ECN])
+		q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
+
 	q->loss_model = CLG_RANDOM;
 	if (tb[TCA_NETEM_LOSS])
 		ret = get_loss_clg(sch, tb[TCA_NETEM_LOSS]);
@@ -881,6 +890,9 @@ static int netem_dump(struct Qdisc *sch,
 	rate.cell_overhead = q->cell_overhead;
 	NLA_PUT(skb, TCA_NETEM_RATE, sizeof(rate), &rate);
 
+	if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
+		goto nla_put_failure;
+
 	if (dump_loss_model(q, skb) != 0)
 		goto nla_put_failure;