netdev - [PATCH v2 net-next 08/14] tcp: move increment of num

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Message-Id: <20250918162133.111922-9-chia-yu.chang@nokia-bell-labs.com>
Date: Thu, 18 Sep 2025 18:21:27 +0200
From: chia-yu.chang@...ia-bell-labs.com
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Cc: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
Subject: [PATCH v2 net-next 08/14] tcp: move increment of num_retrans

From: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>

Before this patch, num_retrans = 0 for the first SYN/ACK and the first
retransmitted SYN/ACK; however, an upcoming change will need to
differentiate between those two conditions. This patch moves the
increment of num_tranns before rtx_syn_ack() so we can distinguish
between these two cases when making SYN/ACK.

Signed-off-by: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
---
 net/ipv4/tcp_output.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 1c372fe0e57f..bf90c2b33af3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -4593,6 +4593,7 @@ int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)
 	/* Paired with WRITE_ONCE() in sock_setsockopt() */
 	if (READ_ONCE(sk->sk_txrehash) == SOCK_TXREHASH_ENABLED)
 		WRITE_ONCE(tcp_rsk(req)->txhash, net_tx_rndhash());
+	WRITE_ONCE(req->num_retrans, req->num_retrans + 1);
 	res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL,
 				  NULL);
 	if (!res) {
@@ -4606,7 +4607,8 @@ int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)
 			tcp_sk_rw(sk)->total_retrans++;
 		}
 		trace_tcp_retransmit_synack(sk, req);
-		WRITE_ONCE(req->num_retrans, req->num_retrans + 1);
+	} else {
+		WRITE_ONCE(req->num_retrans, req->num_retrans - 1);
 	}
 	return res;
 }
-- 
2.34.1