tcp: move inet6_csk_update_pmtu() to tcp_ipv6.c

This function is only called from tcp_v6_mtu_reduced() and can be
(auto)inlined by the compiler.

Note that inet6_csk_route_socket() is no longer (auto)inlined,
which is a good thing as it is slow path.

$ scripts/bloat-o-meter -t vmlinux.0 vmlinux.1

add/remove: 0/2 grow/shrink: 2/0 up/down: 93/-129 (-36)
Function                                     old     new   delta
tcp_v6_mtu_reduced                           139     228     +89
inet6_csk_route_socket                       486     490      +4
__pfx_inet6_csk_update_pmtu                   16       -     -16
inet6_csk_update_pmtu                        113       -    -113
Total: Before=25076512, After=25076476, chg -0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260223153047.886683-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 20 insertions, 18 deletions

diff --git a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
index ece8dabd209a..b814e1acc512 100644
--- a/include/net/inet6_connection_sock.h
+++ b/include/net/inet6_connection_sock.h
@@ -18,6 +18,9 @@ struct sk_buff;
 struct sock;
 struct sockaddr;
 
+struct dst_entry *inet6_csk_route_socket(struct sock *sk,
+					 struct flowi6 *fl6);
+
 struct dst_entry *inet6_csk_route_req(const struct sock *sk,
 				      struct dst_entry *dst,
 				      struct flowi6 *fl6,
@@ -25,5 +28,4 @@ struct dst_entry *inet6_csk_route_req(const struct sock *sk,
 
 int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
 
-struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu);
 #endif /* _INET6_CONNECTION_SOCK_H */
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 11fc2f7de2fe..37534e116899 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -56,8 +56,8 @@ struct dst_entry *inet6_csk_route_req(const struct sock *sk,
 	return dst;
 }
 
-static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
-						struct flowi6 *fl6)
+struct dst_entry *inet6_csk_route_socket(struct sock *sk,
+					 struct flowi6 *fl6)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -118,18 +118,3 @@ int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused
 	return res;
 }
 EXPORT_SYMBOL_GPL(inet6_csk_xmit);
-
-struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
-{
-	struct flowi6 *fl6 = &inet_sk(sk)->cork.fl.u.ip6;
-	struct dst_entry *dst;
-
-	dst = inet6_csk_route_socket(sk, fl6);
-
-	if (IS_ERR(dst))
-		return NULL;
-	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
-
-	dst = inet6_csk_route_socket(sk, fl6);
-	return IS_ERR(dst) ? NULL : dst;
-}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f17da56b449e..07e07afb1ff1 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -349,6 +349,21 @@ failure:
 	return err;
 }
 
+static struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
+{
+	struct flowi6 *fl6 = &inet_sk(sk)->cork.fl.u.ip6;
+	struct dst_entry *dst;
+
+	dst = inet6_csk_route_socket(sk, fl6);
+
+	if (IS_ERR(dst))
+		return NULL;
+	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
+
+	dst = inet6_csk_route_socket(sk, fl6);
+	return IS_ERR(dst) ? NULL : dst;
+}
+
 static void tcp_v6_mtu_reduced(struct sock *sk)
 {
 	struct dst_entry *dst;