[PATCH net-next] net_sched: sch_htb: add per class overlimits counter

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

HTB qdisc overlimits counter is properly increased, but we have no per
class counter, meaning it is difficult to diagnose HTB problems.

This patch adds this counter, visible in "tc -s class show dev eth0",
with current iproute2.

Signed-off-by: Eric Dumazet <eduma...@google.com>
Reported-by: Denys Fedoryshchenko <nuclear...@nuclearcat.com>
---

We have used this at Google for few years already, time to ship it !

 net/sched/sch_htb.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 
7e148376ba528efabe5a53a09653f9161c264be7..c6d7ae81b41f4e277afb93a3003fefcd3f27de35
 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -142,6 +142,7 @@ struct htb_class {
        struct rb_node          node[TC_HTB_NUMPRIO];   /* node for self or 
feed tree */
 
        unsigned int drops ____cacheline_aligned_in_smp;
+       unsigned int            overlimits;
 };
 
 struct htb_level {
@@ -533,6 +534,9 @@ htb_change_class_mode(struct htb_sched *q, struct htb_class 
*cl, s64 *diff)
        if (new_mode == cl->cmode)
                return;
 
+       if (new_mode == HTB_CANT_SEND)
+               cl->overlimits++;
+
        if (cl->prio_activity) {        /* not necessary: speed optimization */
                if (cl->cmode != HTB_CANT_SEND)
                        htb_deactivate_prios(q, cl);
@@ -1143,6 +1147,7 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long 
arg, struct gnet_dump *d)
        struct htb_class *cl = (struct htb_class *)arg;
        struct gnet_stats_queue qs = {
                .drops = cl->drops,
+               .overlimits = cl->overlimits,
        };
        __u32 qlen = 0;