net: sched: consolidate tc_classify{,_compat}

For classifiers getting invoked via tc_classify(), we always need an
extra function call into tc_classify_compat(), as both are being
exported as symbols and tc_classify() itself doesn't do much except
handling of reclassifications when tp->classify() returned with
TC_ACT_RECLASSIFY.

CBQ and ATM are the only qdiscs that directly call into tc_classify_compat(),
all others use tc_classify(). When tc actions are being configured
out in the kernel, tc_classify() effectively does nothing besides
delegating.

We could spare this layer and consolidate both functions. pktgen on
single CPU constantly pushing skbs directly into the netif_receive_skb()
path with a dummy classifier on ingress qdisc attached, improves
slightly from 22.3Mpps to 23.1Mpps.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 30 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index f06aa01d60fd..59c227f26b56 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1806,51 +1806,46 @@ done:
  * to this qdisc, (optionally) tests for protocol and asks
  * specific classifiers.
  */
-int tc_classify_compat(struct sk_buff *skb, const struct tcf_proto *tp,
-		       struct tcf_result *res)
+int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
+		struct tcf_result *res, bool compat_mode)
 {
 	__be16 protocol = tc_skb_protocol(skb);
-	int err;
+#ifdef CONFIG_NET_CLS_ACT
+	const struct tcf_proto *old_tp = tp;
+	int limit = 0;
 
+reclassify:
+#endif
 	for (; tp; tp = rcu_dereference_bh(tp->next)) {
+		int err;
+
 		if (tp->protocol != protocol &&
 		    tp->protocol != htons(ETH_P_ALL))
 			continue;
-		err = tp->classify(skb, tp, res);
 
+		err = tp->classify(skb, tp, res);
+#ifdef CONFIG_NET_CLS_ACT
+		if (unlikely(err == TC_ACT_RECLASSIFY &&
+			     !compat_mode))
+			goto reset;
+#endif
 		if (err >= 0)
 			return err;
 	}
-	return -1;
-}
-EXPORT_SYMBOL(tc_classify_compat);
 
-int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
-		struct tcf_result *res)
-{
-	int err = 0;
-#ifdef CONFIG_NET_CLS_ACT
-	const struct tcf_proto *otp = tp;
-	int limit = 0;
-reclassify:
-#endif
-
-	err = tc_classify_compat(skb, tp, res);
+	return -1;
 #ifdef CONFIG_NET_CLS_ACT
-	if (err == TC_ACT_RECLASSIFY) {
-		tp = otp;
-
-		if (unlikely(limit++ >= MAX_REC_LOOP)) {
-			net_notice_ratelimited("%s: packet reclassify loop rule prio %u protocol %02x\n",
-					       tp->q->ops->id,
-					       tp->prio & 0xffff,
-					       ntohs(tp->protocol));
-			return TC_ACT_SHOT;
-		}
-		goto reclassify;
+reset:
+	if (unlikely(limit++ >= MAX_REC_LOOP)) {
+		net_notice_ratelimited("%s: reclassify loop, rule prio %u, "
+				       "protocol %02x\n", tp->q->ops->id,
+				       tp->prio & 0xffff, ntohs(tp->protocol));
+		return TC_ACT_SHOT;
 	}
+
+	tp = old_tp;
+	goto reclassify;
 #endif
-	return err;
 }
 EXPORT_SYMBOL(tc_classify);