tcp: remove icsk->icsk_retransmit_timer

Now sk->sk_timer is no longer used by TCP keepalive, we can use
its storage for TCP and MPTCP retransmit timers for better
cache locality.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251124175013.1473655-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 11 insertions, 18 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4fc09f9bf25d..97d57c52b9ad 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -737,7 +737,7 @@ void inet_csk_init_xmit_timers(struct sock *sk,
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 
-	timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
+	timer_setup(&sk->tcp_retransmit_timer, retransmit_handler, 0);
 	timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 	timer_setup(&icsk->icsk_keepalive_timer, keepalive_handler, 0);
 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
@@ -750,7 +750,7 @@ void inet_csk_clear_xmit_timers(struct sock *sk)
 	smp_store_release(&icsk->icsk_pending, 0);
 	smp_store_release(&icsk->icsk_ack.pending, 0);
 
-	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
+	sk_stop_timer(sk, &sk->tcp_retransmit_timer);
 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
 	sk_stop_timer(sk, &icsk->icsk_keepalive_timer);
 }
@@ -765,7 +765,7 @@ void inet_csk_clear_xmit_timers_sync(struct sock *sk)
 	smp_store_release(&icsk->icsk_pending, 0);
 	smp_store_release(&icsk->icsk_ack.pending, 0);
 
-	sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
+	sk_stop_timer_sync(sk, &sk->tcp_retransmit_timer);
 	sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
 	sk_stop_timer_sync(sk, &icsk->icsk_keepalive_timer);
 }
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index d2678dfd8118..160080c9021d 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -698,7 +698,7 @@ void tcp_write_timer_handler(struct sock *sk)
 		return;
 
 	if (time_after(tcp_timeout_expires(sk), jiffies)) {
-		sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
+		sk_reset_timer(sk, &sk->tcp_retransmit_timer,
 			       tcp_timeout_expires(sk));
 		return;
 	}
@@ -725,12 +725,10 @@ void tcp_write_timer_handler(struct sock *sk)
 
 static void tcp_write_timer(struct timer_list *t)
 {
-	struct inet_connection_sock *icsk =
-			timer_container_of(icsk, t, icsk_retransmit_timer);
-	struct sock *sk = &icsk->icsk_inet.sk;
+	struct sock *sk = timer_container_of(sk, t, tcp_retransmit_timer);
 
 	/* Avoid locking the socket when there is no pending event. */
-	if (!smp_load_acquire(&icsk->icsk_pending))
+	if (!smp_load_acquire(&inet_csk(sk)->icsk_pending))
 		goto out;
 
 	bh_lock_sock(sk);
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 89a5f63921e6..bb7d634cf312 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -411,9 +411,7 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
 
 static void mptcp_stop_rtx_timer(struct sock *sk)
 {
-	struct inet_connection_sock *icsk = inet_csk(sk);
-
-	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
+	sk_stop_timer(sk, &sk->mptcp_retransmit_timer);
 	mptcp_sk(sk)->timer_ival = 0;
 }
 
@@ -954,12 +952,11 @@ static void __mptcp_flush_join_list(struct sock *sk, struct list_head *join_list
 
 static bool mptcp_rtx_timer_pending(struct sock *sk)
 {
-	return timer_pending(&inet_csk(sk)->icsk_retransmit_timer);
+	return timer_pending(&sk->mptcp_retransmit_timer);
 }
 
 static void mptcp_reset_rtx_timer(struct sock *sk)
 {
-	struct inet_connection_sock *icsk = inet_csk(sk);
 	unsigned long tout;
 
 	/* prevent rescheduling on close */
@@ -967,7 +964,7 @@ static void mptcp_reset_rtx_timer(struct sock *sk)
 		return;
 
 	tout = mptcp_sk(sk)->timer_ival;
-	sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
+	sk_reset_timer(sk, &sk->mptcp_retransmit_timer, jiffies + tout);
 }
 
 bool mptcp_schedule_work(struct sock *sk)
@@ -2354,9 +2351,7 @@ out_err:
 
 static void mptcp_retransmit_timer(struct timer_list *t)
 {
-	struct inet_connection_sock *icsk = timer_container_of(icsk, t,
-							       icsk_retransmit_timer);
-	struct sock *sk = &icsk->icsk_inet.sk;
+	struct sock *sk = timer_container_of(sk, t, mptcp_retransmit_timer);
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
 	bh_lock_sock(sk);
@@ -2975,7 +2970,7 @@ static void __mptcp_init_sock(struct sock *sk)
 	spin_lock_init(&msk->fallback_lock);
 
 	/* re-use the csk retrans timer for MPTCP-level retrans */
-	timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
+	timer_setup(&sk->mptcp_retransmit_timer, mptcp_retransmit_timer, 0);
 	timer_setup(&msk->sk.mptcp_tout_timer, mptcp_tout_timer, 0);
 }