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_red.c b/net/sched/sch_red.c
index 8f5a85b..ce2256a 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -170,6 +170,7 @@
static const struct nla_policy red_policy[TCA_RED_MAX + 1] = {
[TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) },
[TCA_RED_STAB] = { .len = RED_STAB_SIZE },
+ [TCA_RED_MAX_P] = { .type = NLA_U32 },
};
static int red_change(struct Qdisc *sch, struct nlattr *opt)
@@ -179,6 +180,7 @@
struct tc_red_qopt *ctl;
struct Qdisc *child = NULL;
int err;
+ u32 max_P;
if (opt == NULL)
return -EINVAL;
@@ -191,6 +193,8 @@
tb[TCA_RED_STAB] == NULL)
return -EINVAL;
+ max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
+
ctl = nla_data(tb[TCA_RED_PARMS]);
if (ctl->limit > 0) {
@@ -209,8 +213,9 @@
}
red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
- ctl->Plog, ctl->Scell_log,
- nla_data(tb[TCA_RED_STAB]));
+ ctl->Plog, ctl->Scell_log,
+ nla_data(tb[TCA_RED_STAB]),
+ max_P);
del_timer(&q->adapt_timer);
if (ctl->flags & TC_RED_ADAPTATIVE)