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

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

[Eric Dumazet]

Moving tcp_stream_memory_free() to tcp.c allows the compiler
to (auto)inline it from tcp_poll() and tcp_sendmsg_locked()
for better performance.

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 2/0 up/down: 118/0 (118)
Function                                     old     new   delta
tcp_poll                                     840     923     +83
tcp_sendmsg_locked                          4217    4252     +35
Total: Before=22573095, After=22573213, chg +0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp.c      | 13 +++++++++++++
 net/ipv4/tcp_ipv4.c | 14 --------------
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index d5319ebe24525ef9c1f0ea0297eb6c70878e0b29..e4c7cc19de3d9eb45c176ff7e2f71ac5b4f6cd5f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -517,6 +517,19 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
 		bpf_skops_tx_timestamping(sk, skb, BPF_SOCK_OPS_TSTAMP_SENDMSG_CB);
 }
 
+/* @wake is one when sk_stream_write_space() calls us.
+ * This sends EPOLLOUT only if notsent_bytes is half the limit.
+ * This mimics the strategy used in sock_def_write_space().
+ */
+bool tcp_stream_memory_free(const struct sock *sk, int wake)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	u32 notsent_bytes = READ_ONCE(tp->write_seq) - READ_ONCE(tp->snd_nxt);
+
+	return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
+}
+EXPORT_SYMBOL(tcp_stream_memory_free);
+
 static bool tcp_stream_is_readable(struct sock *sk, int target)
 {
 	if (tcp_epollin_ready(sk, target))
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f8a9596e8f4d41563896f02329d20b731fe7961f..ffdf52fbf6463b41d7c712f3710b681ecdf6e2d7 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -3418,20 +3418,6 @@ void tcp4_proc_exit(void)
 }
 #endif /* CONFIG_PROC_FS */
 
-/* @wake is one when sk_stream_write_space() calls us.
- * This sends EPOLLOUT only if notsent_bytes is half the limit.
- * This mimics the strategy used in sock_def_write_space().
- */
-bool tcp_stream_memory_free(const struct sock *sk, int wake)
-{
-	const struct tcp_sock *tp = tcp_sk(sk);
-	u32 notsent_bytes = READ_ONCE(tp->write_seq) -
-			    READ_ONCE(tp->snd_nxt);
-
-	return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
-}
-EXPORT_SYMBOL(tcp_stream_memory_free);
-
 struct proto tcp_prot = {
 	.name			= "TCP",
 	.owner			= THIS_MODULE,
-- 
2.52.0.457.g6b5491de43-goog

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

[Neal Cardwell]

On Thu, Jan 22, 2026 at 4:02 AM Eric Dumazet <edumazet@google.com> wrote:
>
> Moving tcp_stream_memory_free() to tcp.c allows the compiler
> to (auto)inline it from tcp_poll() and tcp_sendmsg_locked()
> for better performance.
>
> $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
> add/remove: 0/0 grow/shrink: 2/0 up/down: 118/0 (118)
> Function                                     old     new   delta
> tcp_poll                                     840     923     +83
> tcp_sendmsg_locked                          4217    4252     +35
> Total: Before=22573095, After=22573213, chg +0.00%
>
> 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_stream_memory_free() to tcp.c

[patchwork-bot+netdevbpf]

Hello:

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

On Thu, 22 Jan 2026 09:02:27 +0000 you wrote:
> Moving tcp_stream_memory_free() to tcp.c allows the compiler
> to (auto)inline it from tcp_poll() and tcp_sendmsg_locked()
> for better performance.
> 
> $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
> add/remove: 0/0 grow/shrink: 2/0 up/down: 118/0 (118)
> Function                                     old     new   delta
> tcp_poll                                     840     923     +83
> tcp_sendmsg_locked                          4217    4252     +35
> Total: Before=22573095, After=22573213, chg +0.00%
> 
> [...]

Here is the summary with links:
  - [net-next] tcp: move tcp_stream_memory_free() to tcp.c
    https://git.kernel.org/netdev/net-next/c/1685e1770856

You are awesome, thank you!
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