net_sched: update hierarchical backlog too

When the bottom qdisc decides to, for example, drop some packet,
it calls qdisc_tree_decrease_qlen() to update the queue length
for all its ancestors, we need to update the backlog too to
keep the stats on root qdisc accurate.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 5 deletions

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 4c834e93dafb..d3fc8f9dd3d4 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -175,7 +175,7 @@ static unsigned int fq_codel_qdisc_drop(struct Qdisc *sch)
 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 {
         struct fq_codel_sched_data *q = qdisc_priv(sch);
-        unsigned int idx;
+        unsigned int idx, prev_backlog;
         struct fq_codel_flow *flow;
         int uninitialized_var(ret);
 
@@ -203,6 +203,7 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
         if (++sch->q.qlen <= sch->limit)
                 return NET_XMIT_SUCCESS;
 
+        prev_backlog = sch->qstats.backlog;
         q->drop_overlimit++;
         /* Return Congestion Notification only if we dropped a packet
          * from this flow.
@@ -211,7 +212,7 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
                 return NET_XMIT_CN;
 
         /* As we dropped a packet, better let upper stack know this */
-        qdisc_tree_decrease_qlen(sch, 1);
+        qdisc_tree_reduce_backlog(sch, 1, prev_backlog - sch->qstats.backlog);
         return NET_XMIT_SUCCESS;
 }
 
@@ -241,6 +242,7 @@ static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
         struct fq_codel_flow *flow;
         struct list_head *head;
         u32 prev_drop_count, prev_ecn_mark;
+        unsigned int prev_backlog;
 
 begin:
         head = &q->new_flows;
@@ -259,6 +261,7 @@ begin:
 
         prev_drop_count = q->cstats.drop_count;
         prev_ecn_mark = q->cstats.ecn_mark;
+        prev_backlog = sch->qstats.backlog;
 
         skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
                             dequeue);
@@ -276,12 +279,14 @@ begin:
         }
         qdisc_bstats_update(sch, skb);
         flow->deficit -= qdisc_pkt_len(skb);
-        /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
+        /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
          * or HTB crashes. Defer it for next round.
          */
         if (q->cstats.drop_count && sch->q.qlen) {
-                qdisc_tree_decrease_qlen(sch, q->cstats.drop_count);
+                qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
+                                          q->cstats.drop_len);
                 q->cstats.drop_count = 0;
+                q->cstats.drop_len = 0;
         }
         return skb;
 }
@@ -372,11 +377,13 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
         while (sch->q.qlen > sch->limit) {
                 struct sk_buff *skb = fq_codel_dequeue(sch);
 
+                q->cstats.drop_len += qdisc_pkt_len(skb);
                 kfree_skb(skb);
                 q->cstats.drop_count++;
         }
-        qdisc_tree_decrease_qlen(sch, q->cstats.drop_count);
+        qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
         q->cstats.drop_count = 0;
+        q->cstats.drop_len = 0;
 
         sch_tree_unlock(sch);
         return 0;