netdev - [PATCH v1 net-next 5/6] tcp: Apply max RTO to non-TFO SYN+ACK.

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Message-ID: <20251106003357.273403-6-kuniyu@google.com>
Date: Thu,  6 Nov 2025 00:32:44 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: Eric Dumazet <edumazet@...gle.com>, Neal Cardwell <ncardwell@...gle.com>, 
	"David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Yuchung Cheng <ycheng@...gle.com>, 
	Kuniyuki Iwashima <kuniyu@...gle.com>, Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v1 net-next 5/6] tcp: Apply max RTO to non-TFO SYN+ACK.

Since commit 54a378f43425 ("tcp: add the ability to control
max RTO"), TFO SYN+ACK RTO is capped by the TFO full sk's
inet_csk(sk)->icsk_rto_max.

The value is inherited from the parent listener.

Let's apply the same cap to non-TFO SYN+ACK.

Note that req->rsk_listener is always non-NULL when we call
tcp_reqsk_timeout() in reqsk_timer_handler() or tcp_check_req().

It could be NULL for SYN cookie req, but we do not use
req->timeout then.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
 include/net/tcp.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index b538fff1a061..93680ff30f0f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -845,7 +845,8 @@ static inline unsigned long tcp_reqsk_timeout(struct request_sock *req)
 {
 	u64 timeout = (u64)req->timeout << req->num_timeout;
 
-	return (unsigned long)min_t(u64, timeout, TCP_RTO_MAX);
+	return (unsigned long)min_t(u64, timeout,
+				    tcp_rto_max(req->rsk_listener));
 }
 
 u32 tcp_delack_max(const struct sock *sk);
-- 
2.51.2.1026.g39e6a42477-goog