[PATCH net-next 2/2] tcp: remove indirect calls for icsk->icsk_af_ops->send_check

[Eric Dumazet <edumazet@google.com>]

Mitigate RETPOLINE costs in __tcp_transmit_skb()
by using INDIRECT_CALL_INET() wrapper.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/ip6_checksum.h | 9 ---------
 include/net/tcp.h          | 3 +++
 net/ipv4/tcp_output.c      | 5 ++++-
 net/ipv6/tcp_ipv6.c        | 7 +++++++
 4 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/include/net/ip6_checksum.h b/include/net/ip6_checksum.h
index 27ec612cd4a4598dc01e4984e61bc42c6ee5e77b..b3f4eaa88672a2e64ec3fbb3e77a60fe383e59d9 100644
--- a/include/net/ip6_checksum.h
+++ b/include/net/ip6_checksum.h
@@ -85,15 +85,6 @@ static inline void tcp_v6_gso_csum_prep(struct sk_buff *skb)
 	th->check = ~tcp_v6_check(0, &ipv6h->saddr, &ipv6h->daddr, 0);
 }
 
-#if IS_ENABLED(CONFIG_IPV6)
-static inline void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
-{
-	struct ipv6_pinfo *np = inet6_sk(sk);
-
-	__tcp_v6_send_check(skb, &np->saddr, &sk->sk_v6_daddr);
-}
-#endif
-
 static inline __sum16 udp_v6_check(int len,
 				   const struct in6_addr *saddr,
 				   const struct in6_addr *daddr,
diff --git a/include/net/tcp.h b/include/net/tcp.h
index e5d7e0b099245cf245a5f1c994d164a9fff66124..cd9cc348dbf9c62efa30d909f23a0ed1b39e4492 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -932,6 +932,9 @@ static inline int tcp_v6_sdif(const struct sk_buff *skb)
 #endif
 	return 0;
 }
+
+INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
+
 #endif
 
 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index be1bd37185d82e5827dfc5105ae74cd815ba1877..04b70fe31fa2cdad739ca49447cf4dd7e9d90cce 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1066,6 +1066,7 @@ static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb,
 
 INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl));
 INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl));
+INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb));
 
 /* This routine actually transmits TCP packets queued in by
  * tcp_do_sendmsg().  This is used by both the initial
@@ -1210,7 +1211,9 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	}
 #endif
 
-	icsk->icsk_af_ops->send_check(sk, skb);
+	INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check,
+			   tcp_v6_send_check, tcp_v4_send_check,
+			   sk, skb);
 
 	if (likely(tcb->tcp_flags & TCPHDR_ACK))
 		tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f67d45ff00b468f8c50053f6d2e430a1f5247db5..4502db706f75349b49672a859492a036a8722bb6 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1811,6 +1811,13 @@ static struct timewait_sock_ops tcp6_timewait_sock_ops = {
 	.twsk_destructor = tcp_twsk_destructor,
 };
 
+INDIRECT_CALLABLE_SCOPE void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+
+	__tcp_v6_send_check(skb, &np->saddr, &sk->sk_v6_daddr);
+}
+
 const struct inet_connection_sock_af_ops ipv6_specific = {
 	.queue_xmit	   = inet6_csk_xmit,
 	.send_check	   = tcp_v6_send_check,
-- 
2.27.0.111.gc72c7da667-goog