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Date: Mon, 06 May 2024 12:46:18 -0400
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Richard Gobert <richardbgobert@gmail.com>, 
 davem@davemloft.net, 
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 willemdebruijn.kernel@gmail.com, 
 kuba@kernel.org, 
 pabeni@redhat.com, 
 dsahern@kernel.org, 
 alobakin@pm.me, 
 shuah@kernel.org, 
 netdev@vger.kernel.org, 
 linux-kernel@vger.kernel.org, 
 linux-kselftest@vger.kernel.org
Cc: Richard Gobert <richardbgobert@gmail.com>
Message-ID: <6639095ab4887_516de294d8@willemb.c.googlers.com.notmuch>
In-Reply-To: <20240506093550.128210-2-richardbgobert@gmail.com>
References: <20240506093550.128210-1-richardbgobert@gmail.com>
 <20240506093550.128210-2-richardbgobert@gmail.com>
Subject: Re: [PATCH net-next v8 1/3] net: gro: use cb instead of
 skb->network_header
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Richard Gobert wrote:
> This patch converts references of skb->network_header to napi_gro_cb's
> network_offset and inner_network_offset.
> 
> Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
> ---
>  include/net/gro.h        | 9 +++++++--
>  net/ipv4/af_inet.c       | 4 ----
>  net/ipv4/tcp_offload.c   | 3 ++-
>  net/ipv6/ip6_offload.c   | 5 ++---
>  net/ipv6/tcpv6_offload.c | 3 ++-
>  5 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/include/net/gro.h b/include/net/gro.h
> index c1d4ca0463a1..1faff23b66e8 100644
> --- a/include/net/gro.h
> +++ b/include/net/gro.h
> @@ -181,12 +181,17 @@ static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen,
>  	return ptr;
>  }
>  
> +static inline int skb_gro_network_offset(const struct sk_buff *skb)
> +{
> +	return NAPI_GRO_CB(skb)->network_offsets[NAPI_GRO_CB(skb)->encap_mark];
> +}
> +

The fact that .._receive sets encap_mark, but .._complete must read
encapsulation, due to the clear in udp_gro_complete, is non-obvious.

Can you add a comment to clarify this or rename this to
skb_gro_receive_network_offset?

>  static inline void *skb_gro_network_header(const struct sk_buff *skb)
>  {
>  	if (skb_gro_may_pull(skb, skb_gro_offset(skb)))
> -		return skb_gro_header_fast(skb, skb_network_offset(skb));
> +		return skb_gro_header_fast(skb, skb_gro_network_offset(skb));
>  
> -	return skb_network_header(skb);
> +	return skb->data + skb_gro_network_offset(skb);
>  }