From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>, David Ahern <dsahern@kernel.org>,
Kuniyuki Iwashima <kuniyu@google.com>,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>
Subject: [PATCH net-next 2/8] ipv6: add some unlikely()/likely() clauses in ip6_output.c
Date: Fri, 30 Jan 2026 21:02:57 +0000 [thread overview]
Message-ID: <20260130210303.3888261-3-edumazet@google.com> (raw)
In-Reply-To: <20260130210303.3888261-1-edumazet@google.com>
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: Eric Dumazet <edumazet@google.com>
---
net/ipv6/ip6_output.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index e4bed95ae5bba173c2418d402cba46e946335219..5c2cfcc3cf6e56192123c5830250865d37e72581 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -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;
--
2.53.0.rc1.225.gd81095ad13-goog
next prev parent reply other threads:[~2026-01-30 21:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-30 21:02 [PATCH net-next 0/8] ipv6: misc changes in output path Eric Dumazet
2026-01-30 21:02 ` [PATCH net-next 1/8] ipv6: pass proto by value to ipv6_push_nfrag_opts() and ipv6_push_frag_opts() Eric Dumazet
2026-01-31 6:29 ` Kuniyuki Iwashima
2026-01-30 21:02 ` Eric Dumazet [this message]
2026-01-31 6:30 ` [PATCH net-next 2/8] ipv6: add some unlikely()/likely() clauses in ip6_output.c Kuniyuki Iwashima
2026-01-30 21:02 ` [PATCH net-next 3/8] ipv6: use __skb_push() in ip6_xmit() Eric Dumazet
2026-01-31 6:32 ` Kuniyuki Iwashima
2026-01-30 21:02 ` [PATCH net-next 4/8] ipv6: use SKB_DROP_REASON_PKT_TOO_BIG " Eric Dumazet
2026-01-31 6:33 ` Kuniyuki Iwashima
2026-01-30 21:03 ` [PATCH net-next 5/8] inet: add dst4_mtu() and dst6_mtu() helpers Eric Dumazet
2026-01-31 6:34 ` Kuniyuki Iwashima
2026-01-30 21:03 ` [PATCH net-next 6/8] ipv6: use dst6_mtu() instead of dst_mtu() Eric Dumazet
2026-01-31 6:39 ` Kuniyuki Iwashima
2026-01-30 21:03 ` [PATCH net-next 7/8] ipv4: use dst4_mtu() " Eric Dumazet
2026-01-31 6:42 ` Kuniyuki Iwashima
2026-01-30 21:03 ` [PATCH net-next 8/8] ipv6: colocate inet6_cork in inet_cork_full Eric Dumazet
2026-01-31 6:46 ` Kuniyuki Iwashima
2026-02-03 2:00 ` [PATCH net-next 0/8] ipv6: misc changes in output path patchwork-bot+netdevbpf
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