netdev - Re: [PATCH v2 net] net: skip offload for NETIF_F_IPV6

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Message-ID: <4919277.OV4Wx5bFTl@benoit.monin>
Date: Tue, 31 Dec 2024 16:24:26 +0100
From: Benoît Monin <benoit.monin@....fr>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Jiri Pirko <jiri@...nulli.us>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Lorenzo Bianconi <lorenzo@...nel.org>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject:
 Re: [PATCH v2 net] net: skip offload for NETIF_F_IPV6_CSUM if ipv6 header
 contains extension

Hi,

23/12/2024 Eric Dumazet wrote:
[...]
> 
> FYI, this patch broke BIG TCP over IPv6.
> 
> [  239.698598] Oops skb_network_header_len()=48 skb->len=67210
> [  239.704122] skb len=67210 headroom=162 headlen=94 tailroom=0
>                mac=(162,14) mac_len=0 net=(176,48) trans=224
>                shinfo(txflags=0 nr_frags=3 gso(size=1428 type=16 segs=47))
>                csum(0x1000e0 start=224 offset=16 ip_summed=3
> complete_sw=0 valid=0 level=0)
>                hash(0xadf29e31 sw=0 l4=1) proto=0x86dd pkttype=0 iif=0
>                priority=0x18020 mark=0x0 alloc_cpu=46 vlan_all=0x0
>                encapsulation=0 inner(proto=0x0000, mac=0, net=0,
> trans=0)\x00, net=0, trans=0)
> [  239.704153] dev name=eth2 feat=0x0000030000114ab3
> [  239.704155] sk family=10 type=1 proto=6
[...]
What is the driver of eth2?
Since it was working before the patch, it means that the hardware is able to 
deal with variable-sized IP header. So shouldn't its features contains 
NETIF_F_HW_CSUM instead of NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM?

-- 
Benoît