[PATCH net-next] tcp: move icsk_clean_acked to a better location

[PATCH net-next] tcp: move icsk_clean_acked to a better location

[Eric Dumazet]

As a followup of my presentation in Zagreb for netdev 0x19:

icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE
is enabled from tcp_ack().

Rename it to tcp_clean_acked, move it to tcp_sock structure
in the tcp_sock_read_rx for better cache locality in TCP
fast path.

Define this field only when CONFIG_TLS_DEVICE is enabled
saving 8 bytes on configs not using it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 Documentation/networking/net_cachelines/tcp_sock.rst |  1 +
 include/linux/tcp.h                                  |  3 +++
 include/net/inet_connection_sock.h                   |  2 --
 include/net/tcp.h                                    |  4 ++--
 net/ipv4/tcp.c                                       |  5 +++++
 net/ipv4/tcp_input.c                                 | 12 ++++++------
 net/tls/tls_device.c                                 |  8 ++++----
 7 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/Documentation/networking/net_cachelines/tcp_sock.rst b/Documentation/networking/net_cachelines/tcp_sock.rst
index 1f79765072b10d99e15815fdd8a4633c74051a7e..bc9b2131bf7acc888e8910b1c5926c83de48f9d6 100644
--- a/Documentation/networking/net_cachelines/tcp_sock.rst
+++ b/Documentation/networking/net_cachelines/tcp_sock.rst
@@ -27,6 +27,7 @@ u32                           dsack_dups
 u32                           snd_una                 read_mostly         read_write          tcp_wnd_end,tcp_urg_mode,tcp_minshall_check,tcp_cwnd_validate(tx);tcp_ack,tcp_may_update_window,tcp_clean_rtx_queue(write),tcp_ack_tstamp(rx)
 u32                           snd_sml                 read_write                              tcp_minshall_check,tcp_minshall_update
 u32                           rcv_tstamp                                  read_mostly         tcp_ack
+void *                        tcp_clean_acked                             read_mostly         tcp_ack
 u32                           lsndtime                read_write                              tcp_slow_start_after_idle_check,tcp_event_data_sent
 u32                           last_oow_ack_time
 u32                           compressed_ack_rcv_nxt
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 159b2c59eb6271030dc2c8d58b43229ebef10ea5..1669d95bb0f9aa97e1e74b7b62bb252eb404fbfb 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -244,6 +244,9 @@ struct tcp_sock {
 	struct  minmax rtt_min;
 	/* OOO segments go in this rbtree. Socket lock must be held. */
 	struct rb_root	out_of_order_queue;
+#if defined(CONFIG_TLS_DEVICE)
+	void (*tcp_clean_acked)(struct sock *sk, u32 acked_seq);
+#endif
 	u32	snd_ssthresh;	/* Slow start size threshold		*/
 	u8	recvmsg_inq : 1;/* Indicate # of bytes in queue upon recvmsg */
 	__cacheline_group_end(tcp_sock_read_rx);
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index d9978ffacc970efd308d0011a094aec41b561e65..96e5e4551479a7c55aabeb1aec38fc4cc7d1c958 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -66,7 +66,6 @@ struct inet_connection_sock_af_ops {
  * @icsk_af_ops		   Operations which are AF_INET{4,6} specific
  * @icsk_ulp_ops	   Pluggable ULP control hook
  * @icsk_ulp_data	   ULP private data
- * @icsk_clean_acked	   Clean acked data hook
  * @icsk_ca_state:	   Congestion control state
  * @icsk_retransmits:	   Number of unrecovered [RTO] timeouts
  * @icsk_pending:	   Scheduled timer event
@@ -97,7 +96,6 @@ struct inet_connection_sock {
 	const struct inet_connection_sock_af_ops *icsk_af_ops;
 	const struct tcp_ulp_ops  *icsk_ulp_ops;
 	void __rcu		  *icsk_ulp_data;
-	void (*icsk_clean_acked)(struct sock *sk, u32 acked_seq);
 	unsigned int		  (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
 	__u8			  icsk_ca_state:5,
 				  icsk_ca_initialized:1,
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 7207c52b1fc9ce3cd9cf2a8580310d0e629f82d6..a8171d4d316b8636bdb065ba145942e1c13d64cb 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2770,9 +2770,9 @@ extern struct static_key_false tcp_have_smc;
 #endif
 
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
-void clean_acked_data_enable(struct inet_connection_sock *icsk,
+void clean_acked_data_enable(struct tcp_sock *tp,
 			     void (*cad)(struct sock *sk, u32 ack_seq));
-void clean_acked_data_disable(struct inet_connection_sock *icsk);
+void clean_acked_data_disable(struct tcp_sock *tp);
 void clean_acked_data_flush(void);
 #endif
 
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 46951e74930844af952dfbc57a107b504d4e296b..26465361c81708ebcac64e149b8920b1eae71ede 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -5026,7 +5026,12 @@ static void __init tcp_struct_check(void)
 	CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_rx, rtt_min);
 	CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_rx, out_of_order_queue);
 	CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_rx, snd_ssthresh);
+#if IS_ENABLED(CONFIG_TLS_DEVICE)
+	CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_rx, tcp_clean_acked);
+	CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_rx, 77);
+#else
 	CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_rx, 69);
+#endif
 
 	/* TX read-write hotpath cache lines */
 	CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_write_tx, segs_out);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4e221234808898131a462bc93ee4c9c0ae04309e..36a82c0496e7065d63a61ef4d45499ba34680723 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -118,18 +118,18 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
 static DEFINE_STATIC_KEY_DEFERRED_FALSE(clean_acked_data_enabled, HZ);
 
-void clean_acked_data_enable(struct inet_connection_sock *icsk,
+void clean_acked_data_enable(struct tcp_sock *tp,
 			     void (*cad)(struct sock *sk, u32 ack_seq))
 {
-	icsk->icsk_clean_acked = cad;
+	tp->tcp_clean_acked = cad;
 	static_branch_deferred_inc(&clean_acked_data_enabled);
 }
 EXPORT_SYMBOL_GPL(clean_acked_data_enable);
 
-void clean_acked_data_disable(struct inet_connection_sock *icsk)
+void clean_acked_data_disable(struct tcp_sock *tp)
 {
 	static_branch_slow_dec_deferred(&clean_acked_data_enabled);
-	icsk->icsk_clean_acked = NULL;
+	tp->tcp_clean_acked = NULL;
 }
 EXPORT_SYMBOL_GPL(clean_acked_data_disable);
 
@@ -3962,8 +3962,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
 		if (static_branch_unlikely(&clean_acked_data_enabled.key))
-			if (icsk->icsk_clean_acked)
-				icsk->icsk_clean_acked(sk, ack);
+			if (tp->tcp_clean_acked)
+				tp->tcp_clean_acked(sk, ack);
 #endif
 	}
 
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index e50b6e71df13be57183bcccdd00768f0f5a7cd95..f672a62a9a52f6ea7a0f5c500acdf9538f08d297 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -157,7 +157,7 @@ static void delete_all_records(struct tls_offload_context_tx *offload_ctx)
 	offload_ctx->retransmit_hint = NULL;
 }
 
-static void tls_icsk_clean_acked(struct sock *sk, u32 acked_seq)
+static void tls_tcp_clean_acked(struct sock *sk, u32 acked_seq)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_record_info *info, *temp;
@@ -204,7 +204,7 @@ void tls_device_sk_destruct(struct sock *sk)
 			destroy_record(ctx->open_record);
 		delete_all_records(ctx);
 		crypto_free_aead(ctx->aead_send);
-		clean_acked_data_disable(inet_csk(sk));
+		clean_acked_data_disable(tcp_sk(sk));
 	}
 
 	tls_device_queue_ctx_destruction(tls_ctx);
@@ -1126,7 +1126,7 @@ int tls_set_device_offload(struct sock *sk)
 	start_marker_record->num_frags = 0;
 	list_add_tail(&start_marker_record->list, &offload_ctx->records_list);
 
-	clean_acked_data_enable(inet_csk(sk), &tls_icsk_clean_acked);
+	clean_acked_data_enable(tcp_sk(sk), &tls_tcp_clean_acked);
 	ctx->push_pending_record = tls_device_push_pending_record;
 
 	/* TLS offload is greatly simplified if we don't send
@@ -1172,7 +1172,7 @@ int tls_set_device_offload(struct sock *sk)
 
 release_lock:
 	up_read(&device_offload_lock);
-	clean_acked_data_disable(inet_csk(sk));
+	clean_acked_data_disable(tcp_sk(sk));
 	crypto_free_aead(offload_ctx->aead_send);
 free_offload_ctx:
 	kfree(offload_ctx);
-- 
2.49.0.rc1.451.g8f38331e32-goog

Re: [PATCH net-next] tcp: move icsk_clean_acked to a better location

[Neal Cardwell]

On Mon, Mar 17, 2025 at 4:53 AM Eric Dumazet <edumazet@google.com> wrote:
>
> As a followup of my presentation in Zagreb for netdev 0x19:
>
> icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE
> is enabled from tcp_ack().
>
> Rename it to tcp_clean_acked, move it to tcp_sock structure
> in the tcp_sock_read_rx for better cache locality in TCP
> fast path.
>
> Define this field only when CONFIG_TLS_DEVICE is enabled
> saving 8 bytes on configs not using it.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---

Very nice! Thanks, Eric!

For clarity for readers, at some point I wonder if we might want to
rename clean_acked_data_enable() and clean_acked_data_disable() to
have a tcp_ prefix in their names, since those functions are only
used/declared/defined in a TCP context.

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

neal

Re: [PATCH net-next] tcp: move icsk_clean_acked to a better location

[Sabrina Dubroca]

2025-03-17, 08:53:13 +0000, Eric Dumazet wrote:
> As a followup of my presentation in Zagreb for netdev 0x19:
> 
> icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE
> is enabled from tcp_ack().
> 
> Rename it to tcp_clean_acked, move it to tcp_sock structure
> in the tcp_sock_read_rx for better cache locality in TCP
> fast path.
> 
> Define this field only when CONFIG_TLS_DEVICE is enabled
> saving 8 bytes on configs not using it.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

-- 
Sabrina

Re: [PATCH net-next 1/2] tcp/dccp: remove icsk->icsk_timeout

[Kuniyuki Iwashima]

From: Eric Dumazet <edumazet@google.com>
Date: Mon, 17 Mar 2025 15:14:00 +0000
> icsk->icsk_timeout can be replaced by icsk->icsk_retransmit_timer.expires
> 
> This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>

We may want to add a paired WRITE_ONCE() in __mod_timer() later.

Btw, DCCP removal series is almost ready and I will post it
in the next cycle as the patch queue is long now.

Re: [PATCH net-next] tcp: move icsk_clean_acked to a better location

[Kuniyuki Iwashima]

From: Eric Dumazet <edumazet@google.com>
Date: Mon, 17 Mar 2025 08:53:13 +0000
> As a followup of my presentation in Zagreb for netdev 0x19:
> 
> icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE
> is enabled from tcp_ack().
> 
> Rename it to tcp_clean_acked, move it to tcp_sock structure
> in the tcp_sock_read_rx for better cache locality in TCP
> fast path.
> 
> Define this field only when CONFIG_TLS_DEVICE is enabled
> saving 8 bytes on configs not using it.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Re: [PATCH net-next] tcp: move icsk_clean_acked to a better location

[patchwork-bot+netdevbpf]

Hello:

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

On Mon, 17 Mar 2025 08:53:13 +0000 you wrote:
> As a followup of my presentation in Zagreb for netdev 0x19:
> 
> icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE
> is enabled from tcp_ack().
> 
> Rename it to tcp_clean_acked, move it to tcp_sock structure
> in the tcp_sock_read_rx for better cache locality in TCP
> fast path.
> 
> [...]

Here is the summary with links:
  - [net-next] tcp: move icsk_clean_acked to a better location
    https://git.kernel.org/netdev/net-next/c/1937a0be28c0

You are awesome, thank you!
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