sch_red: generalize accurate MAX_P support to RED/GRED/CHOKE
Now RED uses a Q0.32 number to store max_p (max probability), allow
RED/GRED/CHOKE to use/report full resolution at config/dump time.
Old tc binaries are non aware of new attributes, and still set/get Plog.
New tc binary set/get both Plog and max_p for backward compatibility,
they display "probability value" if they get max_p from new kernels.
# tc -d qdisc show dev ...
...
qdisc red 10: parent 1:1 limit 360Kb min 30Kb max 90Kb ecn ewma 5
probability 0.09 Scell_log 15
Make sure we avoid potential divides by 0 in reciprocal_value(), if
(max_th - min_th) is big.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index 205d369..bef00ac 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -394,6 +394,7 @@
static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
[TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
[TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
+ [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
};
@@ -415,6 +416,7 @@
int err;
struct sk_buff **old = NULL;
unsigned int mask;
+ u32 max_P;
if (opt == NULL)
return -EINVAL;
@@ -427,6 +429,8 @@
tb[TCA_CHOKE_STAB] == NULL)
return -EINVAL;
+ max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
+
ctl = nla_data(tb[TCA_CHOKE_PARMS]);
if (ctl->limit > CHOKE_MAX_QUEUE)
@@ -476,7 +480,8 @@
red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
ctl->Plog, ctl->Scell_log,
- nla_data(tb[TCA_CHOKE_STAB]));
+ nla_data(tb[TCA_CHOKE_STAB]),
+ max_P);
if (q->head == q->tail)
red_end_of_idle_period(&q->parms);
@@ -510,6 +515,7 @@
goto nla_put_failure;
NLA_PUT(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt);
+ NLA_PUT_U32(skb, TCA_CHOKE_MAX_P, q->parms.max_P);
return nla_nest_end(skb, opts);
nla_put_failure: