inet: move ipv6only in sock_common

When an UDP application switches from AF_INET to AF_INET6 sockets, we
have a small performance degradation for IPv4 communications because of
extra cache line misses to access ipv6only information.

This can also be noticed for TCP listeners, as ipv6_only_sock() is also
used from __inet_lookup_listener()->compute_score()

This is magnified when SO_REUSEPORT is used.

Move ipv6only into struct sock_common so that it is available at
no extra cost in lookups.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index e68e0d4af6c9..1649988bd1b6 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -298,7 +298,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
                         tw->tw_tclass = np->tclass;
                         tw->tw_flowlabel = np->flow_label >> 12;
-                        tw->tw_ipv6only = np->ipv6only;
+                        tw->tw_ipv6only = sk->sk_ipv6only;
                 }
 #endif