[PATCH net-next 09/11] ipv6: refactor opts push in __ip6_make_skb()

From: Pavel Begunkov
Date: Thu Apr 28 2022 - 06:58:30 EST


Don't preload v6_cork->opt before we actually need it, it likely to be
saved on the stack and read again for no good reason.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
net/ipv6/ip6_output.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 976554d0fdec..43a541bbcf5f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1855,7 +1855,6 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
struct ipv6_pinfo *np = inet6_sk(sk);
struct net *net = sock_net(sk);
struct ipv6hdr *hdr;
- struct ipv6_txoptions *opt = v6_cork->opt;
struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
struct flowi6 *fl6 = &cork->fl.u.ip6;
unsigned char proto = fl6->flowi6_proto;
@@ -1884,10 +1883,14 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
__skb_pull(skb, skb_network_header_len(skb));

final_dst = &fl6->daddr;
- if (opt && opt->opt_flen)
- ipv6_push_frag_opts(skb, opt, &proto);
- if (opt && opt->opt_nflen)
- ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+ if (v6_cork->opt) {
+ struct ipv6_txoptions *opt = v6_cork->opt;
+
+ if (opt->opt_flen)
+ ipv6_push_frag_opts(skb, opt, &proto);
+ if (opt->opt_nflen)
+ ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+ }

skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
--
2.36.0