[PKT_SCHED]: GRED: Support ECN marking

Adds a new u8 flags in a unused padding area of the netlink
message. Adds ECN marking support to be used instead of dropping
packets immediately.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

2 files changed, 23 insertions, 6 deletions

diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
index d053add3dca7..0ebe320223e2 100644
--- a/include/linux/pkt_sched.h
+++ b/include/linux/pkt_sched.h
@@ -220,8 +220,8 @@ struct tc_gred_sopt
         __u32           DPs;
         __u32           def_DP;
         __u8            grio;
-        __u8            pad1;
-        __u16           pad2;
+        __u8            flags;
+        __u16           pad1;
 };
 
 /* HTB section */
diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index 69f0fd45d4c3..079b0a4ea1c2 100644
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -55,6 +55,7 @@ struct gred_sched
 {
         struct gred_sched_data *tab[MAX_DPs];
         unsigned long   flags;
+        u32             red_flags;
         u32             DPs;
         u32             def;
         struct red_parms wred_set;
@@ -140,6 +141,11 @@ static inline void gred_store_wred_set(struct gred_sched *table,
         table->wred_set.qavg = q->parms.qavg;
 }
 
+static inline int gred_use_ecn(struct gred_sched *t)
+{
+        return t->red_flags & TC_RED_ECN;
+}
+
 static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 {
         struct gred_sched_data *q=NULL;
@@ -198,13 +204,22 @@ static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 
                 case RED_PROB_MARK:
                         sch->qstats.overlimits++;
-                        q->stats.prob_drop++;
-                        goto congestion_drop;
+                        if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
+                                q->stats.prob_drop++;
+                                goto congestion_drop;
+                        }
+
+                        q->stats.prob_mark++;
+                        break;
 
                 case RED_HARD_MARK:
                         sch->qstats.overlimits++;
-                        q->stats.forced_drop++;
-                        goto congestion_drop;
+                        if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
+                                q->stats.forced_drop++;
+                                goto congestion_drop;
+                        }
+                        q->stats.forced_mark++;
+                        break;
         }
 
         if (q->backlog + skb->len <= q->limit) {
@@ -348,6 +363,7 @@ static inline int gred_change_table_def(struct Qdisc *sch, struct rtattr *dps)
         sch_tree_lock(sch);
         table->DPs = sopt->DPs;
         table->def = sopt->def_DP;
+        table->red_flags = sopt->flags;
 
         /*
          * Every entry point to GRED is synchronized with the above code
@@ -489,6 +505,7 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
                 .DPs    = table->DPs,
                 .def_DP = table->def,
                 .grio   = gred_rio_mode(table),
+                .flags  = table->red_flags,
         };
 
         opts = RTA_NEST(skb, TCA_OPTIONS);