net: sched: make bstats per cpu and estimator RCU safe
In order to run qdisc's without locking statistics and estimators
need to be handled correctly.
To resolve bstats make the statistics per cpu. And because this is
only needed for qdiscs that are running without locks which is not
the case for most qdiscs in the near future only create percpu
stats when qdiscs set the TCQ_F_CPUSTATS flag.
Next because estimators use the bstats to calculate packets per
second and bytes per second the estimator code paths are updated
to use the per cpu statistics.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 15e7bee..a95e3b4 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -942,6 +942,13 @@
sch->handle = handle;
if (!ops->init || (err = ops->init(sch, tca[TCA_OPTIONS])) == 0) {
+ if (qdisc_is_percpu_stats(sch)) {
+ sch->cpu_bstats =
+ alloc_percpu(struct gnet_stats_basic_cpu);
+ if (!sch->cpu_bstats)
+ goto err_out4;
+ }
+
if (tca[TCA_STAB]) {
stab = qdisc_get_stab(tca[TCA_STAB]);
if (IS_ERR(stab)) {
@@ -964,8 +971,11 @@
else
root_lock = qdisc_lock(sch);
- err = gen_new_estimator(&sch->bstats, &sch->rate_est,
- root_lock, tca[TCA_RATE]);
+ err = gen_new_estimator(&sch->bstats,
+ sch->cpu_bstats,
+ &sch->rate_est,
+ root_lock,
+ tca[TCA_RATE]);
if (err)
goto err_out4;
}
@@ -984,6 +994,7 @@
return NULL;
err_out4:
+ free_percpu(sch->cpu_bstats);
/*
* Any broken qdiscs that would require a ops->reset() here?
* The qdisc was never in action so it shouldn't be necessary.
@@ -1022,9 +1033,11 @@
because change can't be undone. */
if (sch->flags & TCQ_F_MQROOT)
goto out;
- gen_replace_estimator(&sch->bstats, &sch->rate_est,
- qdisc_root_sleeping_lock(sch),
- tca[TCA_RATE]);
+ gen_replace_estimator(&sch->bstats,
+ sch->cpu_bstats,
+ &sch->rate_est,
+ qdisc_root_sleeping_lock(sch),
+ tca[TCA_RATE]);
}
out:
return 0;
@@ -1299,6 +1312,7 @@
static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
u32 portid, u32 seq, u16 flags, int event)
{
+ struct gnet_stats_basic_cpu __percpu *cpu_bstats = NULL;
struct tcmsg *tcm;
struct nlmsghdr *nlh;
unsigned char *b = skb_tail_pointer(skb);
@@ -1334,7 +1348,10 @@
if (q->ops->dump_stats && q->ops->dump_stats(q, &d) < 0)
goto nla_put_failure;
- if (gnet_stats_copy_basic(&d, &q->bstats) < 0 ||
+ if (qdisc_is_percpu_stats(q))
+ cpu_bstats = q->cpu_bstats;
+
+ if (gnet_stats_copy_basic(&d, cpu_bstats, &q->bstats) < 0 ||
gnet_stats_copy_rate_est(&d, &q->bstats, &q->rate_est) < 0 ||
gnet_stats_copy_queue(&d, &q->qstats) < 0)
goto nla_put_failure;