From: Eric Dumazet <edumazet@google.com>
Date: Mon, 23 Feb 2026 10:07:27 +0000 (+0000)
Subject: tcp: inline __tcp_v4_send_check()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bd5e5e1d41d316c47dd9001104b62033992daf6e;p=thirdparty%2Flinux.git

tcp: inline __tcp_v4_send_check()

Inline __tcp_v4_send_check(), like __tcp_v6_send_check().

Move tcp_v4_send_check() to tcp_output.c close to
its fast path caller (__tcp_transmit_skb()).

Note __tcp_v4_send_check() is still out-of-line for tcp4_gso_segment()
because it is called in an unlikely() section.

$ scripts/bloat-o-meter -t vmlinux.0 vmlinux.1
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-9 (-9)
Function                                     old     new   delta
__tcp_v4_send_check                          130     121      -9
Total: Before=25143100, After=25143091, chg -0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260223100729.3761597-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 40e72b9cb85f0..3c84433f3d57b 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2382,7 +2382,15 @@ void tcp_gro_complete(struct sk_buff *skb);
 static inline void tcp_gro_complete(struct sk_buff *skb) { }
 #endif
 
-void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
+static inline void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr,
+				       __be32 daddr)
+{
+	struct tcphdr *th = tcp_hdr(skb);
+
+	th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
+	skb->csum_start = skb_transport_header(skb) - skb->head;
+	skb->csum_offset = offsetof(struct tcphdr, check);
+}
 
 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
 {
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 6264fc0b2be53..da708aff06230 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -661,24 +661,6 @@ out:
 	return 0;
 }
 
-void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
-{
-	struct tcphdr *th = tcp_hdr(skb);
-
-	th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
-	skb->csum_start = skb_transport_header(skb) - skb->head;
-	skb->csum_offset = offsetof(struct tcphdr, check);
-}
-
-/* This routine computes an IPv4 TCP checksum. */
-void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
-{
-	const struct inet_sock *inet = inet_sk(sk);
-
-	__tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
-}
-EXPORT_IPV6_MOD(tcp_v4_send_check);
-
 #define REPLY_OPTIONS_LEN      (MAX_TCP_OPTION_SPACE / sizeof(__be32))
 
 static bool tcp_v4_ao_sign_reset(const struct sock *sk, struct sk_buff *skb,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 326b58ff1118d..29056d6fc787e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1496,7 +1496,15 @@ static void tcp_rate_skb_sent(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 computes an IPv4 TCP checksum. */
+void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
+{
+	const struct inet_sock *inet = inet_sk(sk);
+
+	__tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
+}
+EXPORT_IPV6_MOD(tcp_v4_send_check);
 
 /* This routine actually transmits TCP packets queued in by
  * tcp_do_sendmsg().  This is used by both the initial