net_sched: gred: actually perform idling in WRED mode

gred_dequeue() and gred_drop() do not seem to get called when the
queue is empty, meaning that we never start idling while in WRED
mode. And since qidlestart is not stored by gred_store_wred_set(),
we would never stop idling while in WRED mode if we ever started.
This messes up the average queue size calculation that influences
packet marking/dropping behavior.

Now, we start WRED mode idling as we are removing the last packet
from the queue. Also we now actually stop WRED mode idling when we
are enqueuing a packet.

Cc: Bruce Osler <brosler@cisco.com>
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 11 deletions

diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index b2570b59d85e..d42234c0f13b 100644
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -136,6 +136,7 @@ static inline void gred_store_wred_set(struct gred_sched *table,
                                        struct gred_sched_data *q)
 {
         table->wred_set.qavg = q->vars.qavg;
+        table->wred_set.qidlestart = q->vars.qidlestart;
 }
 
 static inline int gred_use_ecn(struct gred_sched *t)
@@ -259,16 +260,18 @@ static struct sk_buff *gred_dequeue(struct Qdisc *sch)
                 } else {
                         q->backlog -= qdisc_pkt_len(skb);
 
-                        if (!q->backlog && !gred_wred_mode(t))
-                                red_start_of_idle_period(&q->vars);
+                        if (gred_wred_mode(t)) {
+                                if (!sch->qstats.backlog)
+                                        red_start_of_idle_period(&t->wred_set);
+                        } else {
+                                if (!q->backlog)
+                                        red_start_of_idle_period(&q->vars);
+                        }
                 }
 
                 return skb;
         }
 
-        if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
-                red_start_of_idle_period(&t->wred_set);
-
         return NULL;
 }
 
@@ -290,19 +293,20 @@ static unsigned int gred_drop(struct Qdisc *sch)
                         q->backlog -= len;
                         q->stats.other++;
 
-                        if (!q->backlog && !gred_wred_mode(t))
-                                red_start_of_idle_period(&q->vars);
+                        if (gred_wred_mode(t)) {
+                                if (!sch->qstats.backlog)
+                                        red_start_of_idle_period(&t->wred_set);
+                        } else {
+                                if (!q->backlog)
+                                        red_start_of_idle_period(&q->vars);
+                        }
                 }
 
                 qdisc_drop(skb, sch);
                 return len;
         }
 
-        if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
-                red_start_of_idle_period(&t->wred_set);
-
         return 0;
-
 }
 
 static void gred_reset(struct Qdisc *sch)