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_gred.c b/net/sched/sch_gred.c
index b9493a0..a1b7407 100644
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -34,7 +34,7 @@
struct gred_sched_data {
u32 limit; /* HARD maximal queue length */
- u32 DP; /* the drop pramaters */
+ u32 DP; /* the drop parameters */
u32 bytesin; /* bytes seen on virtualQ so far*/
u32 packetsin; /* packets seen on virtualQ so far*/
u32 backlog; /* bytes on the virtualQ */
@@ -379,7 +379,8 @@
}
static inline int gred_change_vq(struct Qdisc *sch, int dp,
- struct tc_gred_qopt *ctl, int prio, u8 *stab)
+ struct tc_gred_qopt *ctl, int prio,
+ u8 *stab, u32 max_P)
{
struct gred_sched *table = qdisc_priv(sch);
struct gred_sched_data *q;
@@ -400,7 +401,7 @@
red_set_parms(&q->parms,
ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
- ctl->Scell_log, stab);
+ ctl->Scell_log, stab, max_P);
return 0;
}
@@ -409,6 +410,7 @@
[TCA_GRED_PARMS] = { .len = sizeof(struct tc_gred_qopt) },
[TCA_GRED_STAB] = { .len = 256 },
[TCA_GRED_DPS] = { .len = sizeof(struct tc_gred_sopt) },
+ [TCA_GRED_MAX_P] = { .type = NLA_U32 },
};
static int gred_change(struct Qdisc *sch, struct nlattr *opt)
@@ -418,6 +420,7 @@
struct nlattr *tb[TCA_GRED_MAX + 1];
int err, prio = GRED_DEF_PRIO;
u8 *stab;
+ u32 max_P;
if (opt == NULL)
return -EINVAL;
@@ -433,6 +436,8 @@
tb[TCA_GRED_STAB] == NULL)
return -EINVAL;
+ max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
+
err = -EINVAL;
ctl = nla_data(tb[TCA_GRED_PARMS]);
stab = nla_data(tb[TCA_GRED_STAB]);
@@ -457,7 +462,7 @@
sch_tree_lock(sch);
- err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
+ err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P);
if (err < 0)
goto errout_locked;
@@ -498,6 +503,7 @@
struct gred_sched *table = qdisc_priv(sch);
struct nlattr *parms, *opts = NULL;
int i;
+ u32 max_p[MAX_DPs];
struct tc_gred_sopt sopt = {
.DPs = table->DPs,
.def_DP = table->def,
@@ -509,6 +515,14 @@
if (opts == NULL)
goto nla_put_failure;
NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
+
+ for (i = 0; i < MAX_DPs; i++) {
+ struct gred_sched_data *q = table->tab[i];
+
+ max_p[i] = q ? q->parms.max_P : 0;
+ }
+ NLA_PUT(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p);
+
parms = nla_nest_start(skb, TCA_GRED_PARMS);
if (parms == NULL)
goto nla_put_failure;