[v2,net-next,2/2] tcp/dccp: remove icsk->icsk_ack.timeout

Commit Message

Eric Dumazet March 18, 2025, 3:43 p.m. UTC

icsk->icsk_ack.timeout can be replaced by icsk->csk_delack_timer.expires

This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality.

Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: Kuniyuki Iwashima <[e-mail]>
---
v2: rebase after "tcp: cache RTAX_QUICKACK metric in a hot cache line"

 .../net_cachelines/inet_connection_sock.rst		  |  1 -
 include/net/inet_connection_sock.h 				  | 12 ++++++++----
 net/dccp/output.c									  |  5 ++---
 net/dccp/timer.c									  |  4 ++--
 net/ipv4/tcp_output.c								  |  7 +++----
 net/ipv4/tcp_timer.c								  |  5 +++--
 net/mptcp/options.c								  |  1 -
 net/mptcp/protocol.c								  |  1 -
 8 files changed, 18 insertions(+), 18 deletions(-)

--
2.49.0.rc1.451.g8f38331e32-goog

Patch

diff --git a/Documentation/networking/net_cachelines/inet_connection_sock.rst b/Documentation/networking/net_cachelines/inet_connection_sock.rst
index 5fb0dd70c9af76ca68b3406ce76d4b61957c7da9..8fae85ebb773085b249c606ce37872e0566b70b4 100644
--- a/Documentation/networking/net_cachelines/inet_connection_sock.rst
+++ b/Documentation/networking/net_cachelines/inet_connection_sock.rst
@@ -38,7 +38,6 @@  struct icsk_ack_u8				  quick 				 read_write 		 w
 struct icsk_ack_u8 				 pingpong
 struct icsk_ack_u8 				 retry					write_mostly		read_write			inet_csk_clear_xmit_timer,tcp_rearm_rto,tcp_event_new_data_sent,tcp_write_xmit,__tcp_send_ack,tcp_send_ack,
 struct icsk_ack_u8 				 ato					read_mostly 		write_mostly		tcp_dec_quickack_mode,tcp_event_ack_sent,__tcp_transmit_skb,__tcp_send_ack,tcp_send_ack
-struct icsk_ack_unsigned_long		 timeout				read_write			read_write			inet_csk_reset_xmit_timer,tcp_connect
 struct icsk_ack_u32				 lrcvtime				read_write								tcp_finish_connect,tcp_connect,tcp_event_data_sent,__tcp_transmit_skb
 struct icsk_ack_u16				 rcv_mss				write_mostly		read_mostly 		__tcp_select_window,__tcp_cleanup_rbuf,tcp_initialize_rcv_mss,tcp_connect_init
 struct icsk_mtup_int				 search_high			read_write								tcp_mtup_init,tcp_sync_mss,tcp_connect_init,tcp_mtu_check_reprobe,tcp_write_xmit
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 018118da0ce15c5ba5e3b7fcc1b36425794ec9a1..597f2b98dcf565a8512e815d9eae2b521bac7807 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -117,7 +117,6 @@  struct inet_connection_sock {
				  lrcv_flowlabel:20, /* last received ipv6 flowlabel	   */
				  dst_quick_ack:1, /* cache dst RTAX_QUICKACK		   */
				  unused:3;
-		unsigned long	  timeout;	 /* Currently scheduled timeout		   */
		__u32		  lrcvtime;	 /* timestamp of last received data packet */
		__u16		  last_seg_size; /* Size of last incoming segment	   */
		__u16		  rcv_mss;	 /* MSS used for delayed ACK decisions	   */
@@ -195,6 +194,12 @@  icsk_timeout(const struct inet_connection_sock *icsk)
	return READ_ONCE(icsk->icsk_retransmit_timer.expires);
 }

+static inline unsigned long
+icsk_delack_timeout(const struct inet_connection_sock *icsk)
+{
+	return READ_ONCE(icsk->icsk_delack_timer.expires);
+}
+
 static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
 {
	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -230,16 +235,15 @@  static inline void inet_csk_reset_xmit_timer(struct sock *sk, const int what,
		when = max_when;
	}

+	when += jiffies;
	if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0 ||
		what == ICSK_TIME_LOSS_PROBE || what == ICSK_TIME_REO_TIMEOUT) {
		smp_store_release(&icsk->icsk_pending, what);
-		when += jiffies;
		sk_reset_timer(sk, &icsk->icsk_retransmit_timer, when);
	} else if (what == ICSK_TIME_DACK) {
		smp_store_release(&icsk->icsk_ack.pending,
				  icsk->icsk_ack.pending | ICSK_ACK_TIMER);
-		icsk->icsk_ack.timeout = jiffies + when;
-		sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
+		sk_reset_timer(sk, &icsk->icsk_delack_timer, when);
	} else {
		pr_debug("inet_csk BUG: unknown timer value\n");
	}
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 5c2e24f3c39b7ff4ee1d5d96d5e406c96609a022..39cf3430177ac597b0a9fd40bf0d8dfbff5fd92d 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -627,11 +627,10 @@  void dccp_send_delayed_ack(struct sock *sk)
			return;
		}

-		if (!time_before(timeout, icsk->icsk_ack.timeout))
-			timeout = icsk->icsk_ack.timeout;
+		if (!time_before(timeout, icsk_delack_timeout(icsk)))
+			timeout = icsk_delack_timeout(icsk);
	}
	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
-	icsk->icsk_ack.timeout = timeout;
	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 }
 #endif
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 9fd14a3361893d5f2d9f0ad18a65cff963cc7e22..232ac4ae0a73ff31beca730c14d8b02107aeb926 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -185,9 +185,9 @@  static void dccp_delack_timer(struct timer_list *t)
	if (sk->sk_state == DCCP_CLOSED ||
		!(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
		goto out;
-	if (time_after(icsk->icsk_ack.timeout, jiffies)) {
+	if (time_after(icsk_delack_timeout(icsk), jiffies)) {
		sk_reset_timer(sk, &icsk->icsk_delack_timer,
-				   icsk->icsk_ack.timeout);
+				   icsk_delack_timeout(icsk));
		goto out;
	}

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e0a4e5432399a3874e471f2d908bf976350f2696..c29e689d966097fabb83876f21d54201989b444d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -4225,17 +4225,16 @@  void tcp_send_delayed_ack(struct sock *sk)
	/* Use new timeout only if there wasn't a older one earlier. */
	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
		/* If delack timer is about to expire, send ACK now. */
-		if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
+		if (time_before_eq(icsk_delack_timeout(icsk), jiffies + (ato >> 2))) {
			tcp_send_ack(sk);
			return;
		}

-		if (!time_before(timeout, icsk->icsk_ack.timeout))
-			timeout = icsk->icsk_ack.timeout;
+		if (!time_before(timeout, icsk_delack_timeout(icsk)))
+			timeout = icsk_delack_timeout(icsk);
	}
	smp_store_release(&icsk->icsk_ack.pending,
			  icsk->icsk_ack.pending | ICSK_ACK_SCHED | ICSK_ACK_TIMER);
-	icsk->icsk_ack.timeout = timeout;
	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 }

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index d828b74c3e73d75cdae777645e8e8856c0751201..d64383b06a295affb735f60edd4dfd64ad5fb1c8 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -322,8 +322,9 @@  void tcp_delack_timer_handler(struct sock *sk)
	if (!(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
		return;

-	if (time_after(icsk->icsk_ack.timeout, jiffies)) {
-		sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
+	if (time_after(icsk_delack_timeout(icsk), jiffies)) {
+		sk_reset_timer(sk, &icsk->icsk_delack_timer,
+				   icsk_delack_timeout(icsk));
		return;
	}
	icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index fd2de185bc939f8730e87a63ac02a015e610e99c..ad1413e9062d54e60a8441deb12406ed63e4aa72 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -432,7 +432,6 @@  static void clear_3rdack_retransmission(struct sock *sk)
	struct inet_connection_sock *icsk = inet_csk(sk);

	sk_stop_timer(sk, &icsk->icsk_delack_timer);
-	icsk->icsk_ack.timeout = 0;
	icsk->icsk_ack.ato = 0;
	icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 }
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 1ac378ba1d67cd17449ab6c4b4793b65d520ec44..44f7ab463d7550ad728651bad2b1aeb4cd4dea05 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3420,7 +3420,6 @@  static void schedule_3rdack_retransmission(struct sock *ssk)
	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
	smp_store_release(&icsk->icsk_ack.pending,
			  icsk->icsk_ack.pending | ICSK_ACK_SCHED | ICSK_ACK_TIMER);
-	icsk->icsk_ack.timeout = timeout;
	sk_reset_timer(ssk, &icsk->icsk_delack_timer, timeout);
 }