linux-kernel - Re: [PATCH net-next v3 2/3] net: gro: parse ipv6 ext headers without frag0 invalidation

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Date: Wed, 3 Jan 2024 17:46:49 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Richard Gobert <richardbgobert@...il.com>
Cc: davem@...emloft.net, dsahern@...nel.org, kuba@...nel.org, 
	pabeni@...hat.com, shuah@...nel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v3 2/3] net: gro: parse ipv6 ext headers without
 frag0 invalidation

On Wed, Jan 3, 2024 at 3:44 PM Richard Gobert <richardbgobert@...il.com> wrote:
>
> The existing code always pulls the IPv6 header and sets the transport
> offset initially. Then optionally again pulls any extension headers in
> ipv6_gso_pull_exthdrs and sets the transport offset again on return from
> that call. skb->data is set at the start of the first extension header
> before calling ipv6_gso_pull_exthdrs, and must disable the frag0
> optimization because that function uses pskb_may_pull/pskb_pull instead of
> skb_gro_ helpers. It sets the GRO offset to the TCP header with
> skb_gro_pull and sets the transport header. Then returns skb->data to its
> position before this block.
>
> This commit introduces a new helper function - ipv6_gro_pull_exthdrs -
> which is used in ipv6_gro_receive to pull ipv6 ext headers instead of
> ipv6_gso_pull_exthdrs. Thus, there is no modification of skb->data, all
> operations use skb_gro_* helpers, and the frag0 fast path can be taken for
> IPv6 packets with ext headers.
>
> Signed-off-by: Richard Gobert <richardbgobert@...il.com>
> Reviewed-by: Willem de Bruijn <willemb@...gle.com>
> Reviewed-by: David Ahern <dsahern@...nel.org>

Reviewed-by: Eric Dumazet <edumazet@...gle.com>

Thanks !