Commit 2855e492 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

ipv6: add some unlikely()/likely() clauses in ip6_output.c 



1) daddr is unlikely a multicast in ip6_finish_output2().

2) ip6_finish_output_gso_slowpath_drop() should not be called often.

3) ip6_fragment() should not be called often.

4) opt is unlikely to be set.

5) ip6_xmit() and ip6_forward() mostly sends not too big packets.

6) Most __ip6_make_skb() calls are for UDP packets,
   not ICMPV6 ones.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260130210303.3888261-3-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1bc46dd2

net/ipv6/ip6_output.c

+12 −12
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 


	hdr = ipv6_hdr(skb);

	daddr = &hdr->daddr;

	if (ipv6_addr_is_multicast(daddr)) {

	if (unlikely(ipv6_addr_is_multicast(daddr))) {

		if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&

		    ((mroute6_is_socket(net, skb) &&

		     !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
@@ -179,8 +179,8 @@ ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk, 
static int ip6_finish_output_gso(struct net *net, struct sock *sk,

				 struct sk_buff *skb, unsigned int mtu)

{

	if (!(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&

	    !skb_gso_validate_network_len(skb, mtu))

	if (unlikely(!(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&

	    !skb_gso_validate_network_len(skb, mtu)))

		return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);



	return ip6_finish_output2(net, sk, skb);
@@ -202,8 +202,8 @@ static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff 
	if (skb_is_gso(skb))

		return ip6_finish_output_gso(net, sk, skb, mtu);



	if (skb->len > mtu ||

	    (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))

	if (unlikely(skb->len > mtu ||

	    (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size)))

		return ip6_fragment(net, sk, skb, ip6_finish_output2);



	return ip6_finish_output2(net, sk, skb);
@@ -301,7 +301,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, 
		}

	}



	if (opt) {

	if (unlikely(opt)) {

		seg_len += opt->opt_nflen + opt->opt_flen;



		if (opt->opt_flen)
@@ -354,7 +354,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, 
	skb->mark = mark;



	mtu = dst_mtu(dst);

	if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {

	if (likely((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb))) {

		IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);



		/* if egress device is enslaved to an L3 master device pass the
@@ -654,7 +654,7 @@ int ip6_forward(struct sk_buff *skb) 
	if (mtu < IPV6_MIN_MTU)

		mtu = IPV6_MIN_MTU;



	if (ip6_pkt_too_big(skb, mtu)) {

	if (unlikely(ip6_pkt_too_big(skb, mtu))) {

		/* Again, force OUTPUT device used as source address */

		skb->dev = dev;

		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
@@ -1368,7 +1368,7 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork, 
	/*

	 * setup for corking

	 */

	if (opt) {

	if (unlikely(opt)) {

		if (WARN_ON(v6_cork->opt))

			return -EINVAL;
@@ -1885,7 +1885,7 @@ static void ip6_cork_steal_dst(struct sk_buff *skb, struct inet_cork_full *cork) 
static void ip6_cork_release(struct inet_cork_full *cork,

			     struct inet6_cork *v6_cork)

{

	if (v6_cork->opt) {

	if (unlikely(v6_cork->opt)) {

		struct ipv6_txoptions *opt = v6_cork->opt;



		kfree(opt->dst0opt);
@@ -1941,7 +1941,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk, 
	__skb_pull(skb, skb_network_header_len(skb));



	final_dst = &fl6->daddr;

	if (opt) {

	if (unlikely(opt)) {

		if (opt->opt_flen)

			proto = ipv6_push_frag_opts(skb, opt, proto);

		if (opt->opt_nflen)
@@ -1969,7 +1969,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk, 


	ip6_cork_steal_dst(skb, cork);

	IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);

	if (proto == IPPROTO_ICMPV6) {

	if (unlikely(proto == IPPROTO_ICMPV6)) {

		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));

		u8 icmp6_type;