From d722762c4eaa918d3d2f78b41cca3f480a616d65 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= <ij@kernel.org>
Date: Wed, 5 Mar 2025 23:38:50 +0100
Subject: [PATCH] tcp: AccECN support to tcp_add_backlog
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AE flag needs to be preserved for AccECN.

Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/tcp_ipv4.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fab684221bf7..87f270ebc635 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2051,7 +2051,8 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
 	    !((TCP_SKB_CB(tail)->tcp_flags &
 	      TCP_SKB_CB(skb)->tcp_flags) & TCPHDR_ACK) ||
 	    ((TCP_SKB_CB(tail)->tcp_flags ^
-	      TCP_SKB_CB(skb)->tcp_flags) & (TCPHDR_ECE | TCPHDR_CWR)) ||
+	      TCP_SKB_CB(skb)->tcp_flags) &
+	     (TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE)) ||
 	    !tcp_skb_can_collapse_rx(tail, skb) ||
 	    thtail->doff != th->doff ||
 	    memcmp(thtail + 1, th + 1, hdrlen - sizeof(*th)))
-- 
2.50.1