netdev - [PATCH net-next 2/3] ipv6: remove IP6SKB

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Message-ID: <20251127091325.7248-3-maklimek97@gmail.com>
Date: Thu, 27 Nov 2025 10:13:24 +0100
From: Mariusz Klimek <maklimek97@...il.com>
To: netdev@...r.kernel.org
Cc: Mariusz Klimek <maklimek97@...il.com>
Subject: [PATCH net-next 2/3] ipv6: remove IP6SKB_FAKEJUMBO flag

This patch removes the IP6SKB_FAKEJUMBO flag that is used as a work-around
to bypass MTU validation of BIG TCP jumbograms due to a bug in
skb_gso_network_seglen. This work-around is no longer required now that the
bug is fixed.

Signed-off-by: Mariusz Klimek <maklimek97@...il.com>
---
 include/linux/ipv6.h  | 1 -
 net/ipv6/ip6_output.c | 4 +---
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 7294e4e89b79..9f076171106e 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -155,7 +155,6 @@ struct inet6_skb_parm {
 #define IP6SKB_L3SLAVE         64
 #define IP6SKB_JUMBOGRAM      128
 #define IP6SKB_SEG6	      256
-#define IP6SKB_FAKEJUMBO      512
 #define IP6SKB_MULTIPATH      1024
 #define IP6SKB_MCROUTE        2048
 };
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f904739e99b9..9af9ec6bdb8c 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -179,8 +179,7 @@ ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
 static int ip6_finish_output_gso(struct net *net, struct sock *sk,
 				 struct sk_buff *skb, unsigned int mtu)
 {
-	if (!(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&
-	    !skb_gso_validate_network_len(skb, mtu))
+	if (!skb_gso_validate_network_len(skb, mtu))
 		return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
 
 	return ip6_finish_output2(net, sk, skb);
@@ -323,7 +322,6 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
 
 		proto = IPPROTO_HOPOPTS;
 		seg_len = 0;
-		IP6CB(skb)->flags |= IP6SKB_FAKEJUMBO;
 	}
 
 	skb_push(skb, sizeof(struct ipv6hdr));
-- 
2.47.3