[PATCH net-next] tcp: move tcp_rate_skb_sent() to tcp_output.c

[PATCH net-next] tcp: move tcp_rate_skb_sent() to tcp_output.c

[Eric Dumazet]

It is only called from __tcp_transmit_skb() and __tcp_retransmit_skb().

Move it in tcp_output.c and make it static.

clang compiler is now able to inline it from __tcp_transmit_skb().

gcc compiler inlines it in the two callers, which is also fine.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/tcp.h     |  1 -
 net/ipv4/tcp_output.c | 35 +++++++++++++++++++++++++++++++++++
 net/ipv4/tcp_rate.c   | 35 -----------------------------------
 3 files changed, 35 insertions(+), 36 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index ef0fee58fde82620399df49a35c7ecae8e34068e..15f9b20f851fe322f4417ff403c3965436aa3f9f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1356,7 +1356,6 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
 void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
 
 /* From tcp_rate.c */
-void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
 			    struct rate_sample *rs);
 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 479afb714bdf901cdf733c94cd7f22bd705c9d02..256b669e8d3b4a4d191e61e79784e412aaef8965 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1432,6 +1432,41 @@ static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb,
 	list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
 }
 
+/* Snapshot the current delivery information in the skb, to generate
+ * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
+ */
+static void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	 /* In general we need to start delivery rate samples from the
+	  * time we received the most recent ACK, to ensure we include
+	  * the full time the network needs to deliver all in-flight
+	  * packets. If there are no packets in flight yet, then we
+	  * know that any ACKs after now indicate that the network was
+	  * able to deliver those packets completely in the sampling
+	  * interval between now and the next ACK.
+	  *
+	  * Note that we use packets_out instead of tcp_packets_in_flight(tp)
+	  * because the latter is a guess based on RTO and loss-marking
+	  * heuristics. We don't want spurious RTOs or loss markings to cause
+	  * a spuriously small time interval, causing a spuriously high
+	  * bandwidth estimate.
+	  */
+	if (!tp->packets_out) {
+		u64 tstamp_us = tcp_skb_timestamp_us(skb);
+
+		tp->first_tx_mstamp  = tstamp_us;
+		tp->delivered_mstamp = tstamp_us;
+	}
+
+	TCP_SKB_CB(skb)->tx.first_tx_mstamp	= tp->first_tx_mstamp;
+	TCP_SKB_CB(skb)->tx.delivered_mstamp	= tp->delivered_mstamp;
+	TCP_SKB_CB(skb)->tx.delivered		= tp->delivered;
+	TCP_SKB_CB(skb)->tx.delivered_ce	= tp->delivered_ce;
+	TCP_SKB_CB(skb)->tx.is_app_limited	= tp->app_limited ? 1 : 0;
+}
+
 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));
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index a8f6d9d06f2eb1893c65dec678edb92211fee52f..98eb346f986ef24969f804c3b55acbf60d2ec299 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -34,41 +34,6 @@
  * ready to send in the write queue.
  */
 
-/* Snapshot the current delivery information in the skb, to generate
- * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
- */
-void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-
-	 /* In general we need to start delivery rate samples from the
-	  * time we received the most recent ACK, to ensure we include
-	  * the full time the network needs to deliver all in-flight
-	  * packets. If there are no packets in flight yet, then we
-	  * know that any ACKs after now indicate that the network was
-	  * able to deliver those packets completely in the sampling
-	  * interval between now and the next ACK.
-	  *
-	  * Note that we use packets_out instead of tcp_packets_in_flight(tp)
-	  * because the latter is a guess based on RTO and loss-marking
-	  * heuristics. We don't want spurious RTOs or loss markings to cause
-	  * a spuriously small time interval, causing a spuriously high
-	  * bandwidth estimate.
-	  */
-	if (!tp->packets_out) {
-		u64 tstamp_us = tcp_skb_timestamp_us(skb);
-
-		tp->first_tx_mstamp  = tstamp_us;
-		tp->delivered_mstamp = tstamp_us;
-	}
-
-	TCP_SKB_CB(skb)->tx.first_tx_mstamp	= tp->first_tx_mstamp;
-	TCP_SKB_CB(skb)->tx.delivered_mstamp	= tp->delivered_mstamp;
-	TCP_SKB_CB(skb)->tx.delivered		= tp->delivered;
-	TCP_SKB_CB(skb)->tx.delivered_ce	= tp->delivered_ce;
-	TCP_SKB_CB(skb)->tx.is_app_limited	= tp->app_limited ? 1 : 0;
-}
-
 /* When an skb is sacked or acked, we fill in the rate sample with the (prior)
  * delivery information when the skb was last transmitted.
  *
-- 
2.52.0.457.g6b5491de43-goog

Re: [PATCH net-next] tcp: move tcp_rate_skb_sent() to tcp_output.c

[Neal Cardwell]

On Wed, Jan 14, 2026 at 11:51 AM Eric Dumazet <edumazet@google.com> wrote:
>
> It is only called from __tcp_transmit_skb() and __tcp_retransmit_skb().
>
> Move it in tcp_output.c and make it static.
>
> clang compiler is now able to inline it from __tcp_transmit_skb().
>
> gcc compiler inlines it in the two callers, which is also fine.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---

Reviewed-by: Neal Cardwell <ncardwell@google.com>

Thanks, Eric!

neal

Re: [PATCH net-next] tcp: move tcp_rate_skb_sent() to tcp_output.c

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 14 Jan 2026 16:51:09 +0000 you wrote:
> It is only called from __tcp_transmit_skb() and __tcp_retransmit_skb().
> 
> Move it in tcp_output.c and make it static.
> 
> clang compiler is now able to inline it from __tcp_transmit_skb().
> 
> gcc compiler inlines it in the two callers, which is also fine.
> 
> [...]

Here is the summary with links:
  - [net-next] tcp: move tcp_rate_skb_sent() to tcp_output.c
    https://git.kernel.org/netdev/net-next/c/f10ab9d3a7ea

You are awesome, thank you!
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