ipv6: make lookups simpler and faster

TCP listener refactoring, part 4 :

To speed up inet lookups, we moved IPv4 addresses from inet to struct
sock_common

Now is time to do the same for IPv6, because it permits us to have fast
lookups for all kind of sockets, including upcoming SYN_RECV.

Getting IPv6 addresses in TCP lookups currently requires two extra cache
lines, plus a dereference (and memory stall).

inet6_sk(sk) does the dereference of inet_sk(__sk)->pinet6

This patch is way bigger than its IPv4 counter part, because for IPv4,
we could add aliases (inet_daddr, inet_rcv_saddr), while on IPv6,
it's not doable easily.

inet6_sk(sk)->daddr becomes sk->sk_v6_daddr
inet6_sk(sk)->rcv_saddr becomes sk->sk_v6_rcv_saddr

And timewait socket also have tw->tw_v6_daddr & tw->tw_v6_rcv_saddr
at the same offset.

We get rid of INET6_TW_MATCH() as INET6_MATCH() is now the generic
macro.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 5ebee2d..f0a7ada 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -906,8 +906,8 @@
 #if IS_ENABLED(CONFIG_IPV6)
 	} else if ((tunnel->version == 2) &&
 		   (tunnel->sock->sk_family == AF_INET6)) {
-		struct ipv6_pinfo *np = inet6_sk(tunnel->sock);
 		struct sockaddr_pppol2tpin6 sp;
+
 		len = sizeof(sp);
 		memset(&sp, 0, len);
 		sp.sa_family	= AF_PPPOX;
@@ -920,13 +920,13 @@
 		sp.pppol2tp.d_session = session->peer_session_id;
 		sp.pppol2tp.addr.sin6_family = AF_INET6;
 		sp.pppol2tp.addr.sin6_port = inet->inet_dport;
-		memcpy(&sp.pppol2tp.addr.sin6_addr, &np->daddr,
-		       sizeof(np->daddr));
+		memcpy(&sp.pppol2tp.addr.sin6_addr, &tunnel->sock->sk_v6_daddr,
+		       sizeof(tunnel->sock->sk_v6_daddr));
 		memcpy(uaddr, &sp, len);
 	} else if ((tunnel->version == 3) &&
 		   (tunnel->sock->sk_family == AF_INET6)) {
-		struct ipv6_pinfo *np = inet6_sk(tunnel->sock);
 		struct sockaddr_pppol2tpv3in6 sp;
+
 		len = sizeof(sp);
 		memset(&sp, 0, len);
 		sp.sa_family	= AF_PPPOX;
@@ -939,8 +939,8 @@
 		sp.pppol2tp.d_session = session->peer_session_id;
 		sp.pppol2tp.addr.sin6_family = AF_INET6;
 		sp.pppol2tp.addr.sin6_port = inet->inet_dport;
-		memcpy(&sp.pppol2tp.addr.sin6_addr, &np->daddr,
-		       sizeof(np->daddr));
+		memcpy(&sp.pppol2tp.addr.sin6_addr, &tunnel->sock->sk_v6_daddr,
+		       sizeof(tunnel->sock->sk_v6_daddr));
 		memcpy(uaddr, &sp, len);
 #endif
 	} else if (tunnel->version == 3) {