net: use jump label patching for ingress qdisc in __netif_receive_skb_core
Even if we make use of classifier and actions from the egress
path, we're going into handle_ing() executing additional code
on a per-packet cost for ingress qdisc, just to realize that
nothing is attached on ingress.
Instead, this can just be blinded out as a no-op entirely with
the use of a static key. On input fast-path, we already make
use of static keys in various places, e.g. skb time stamping,
in RPS, etc. It makes sense to not waste time when we're assured
that no ingress qdisc is attached anywhere.
Enabling/disabling of that code path is being done via two
helpers, namely net_{inc,dec}_ingress_queue(), that are being
invoked under RTNL mutex when a ingress qdisc is being either
initialized or destructed.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
index eb5b844..4cdbfb8 100644
--- a/net/sched/sch_ingress.c
+++ b/net/sched/sch_ingress.c
@@ -88,11 +88,19 @@
/* ------------------------------------------------------------- */
+static int ingress_init(struct Qdisc *sch, struct nlattr *opt)
+{
+ net_inc_ingress_queue();
+
+ return 0;
+}
+
static void ingress_destroy(struct Qdisc *sch)
{
struct ingress_qdisc_data *p = qdisc_priv(sch);
tcf_destroy_chain(&p->filter_list);
+ net_dec_ingress_queue();
}
static int ingress_dump(struct Qdisc *sch, struct sk_buff *skb)
@@ -124,6 +132,7 @@
.id = "ingress",
.priv_size = sizeof(struct ingress_qdisc_data),
.enqueue = ingress_enqueue,
+ .init = ingress_init,
.destroy = ingress_destroy,
.dump = ingress_dump,
.owner = THIS_MODULE,