linux-kernel - Re: [PATCH v3] net: ethernet: use ip

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Message-ID: <4850b81e-d426-4abd-87f8-2712cd0b5de4@wanadoo.fr>
Date: Wed, 7 Aug 2024 14:28:06 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Moon Yeounsu <yyyynoom@...il.com>, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] net: ethernet: use ip_hdrlen() instead of bit shift

Le 07/08/2024 à 12:07, Moon Yeounsu a écrit :
> `ip_hdr(skb)->ihl << 2` is the same as `ip_hdrlen(skb)`
> Therefore, we should use a well-defined function not a bit shift
> to find the header length.
> 
> It also compresses two lines to a single line.
> 
> Signed-off-by: Moon Yeounsu <yyyynoom@...il.com>

Reviewed-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>

> ---
> v1: use ip_hdrlen() instead of bit shift
> Reference: https://lore.kernel.org/all/20240802054421.5428-1-yyyynoom@gmail.com/
> 
> v2: remove unnecessary parentheses
> - Remove extra () [Christophe Jaillet, Simon Horman]
> - Break long lines [Simon Horman]
> Reference: https://lore.kernel.org/all/20240803022949.28229-1-yyyynoom@gmail.com/
> 
> v3: create a standalone patch
> - Start with a new thread
> - Include the change logs,
> - Create a standalone patch [Christophe Jaillet]
> 
>   drivers/net/ethernet/jme.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/jme.c b/drivers/net/ethernet/jme.c
> index b06e24562973..d8be0e4dcb07 100644
> --- a/drivers/net/ethernet/jme.c
> +++ b/drivers/net/ethernet/jme.c
> @@ -946,15 +946,13 @@ jme_udpsum(struct sk_buff *skb)
>   	if (skb->protocol != htons(ETH_P_IP))
>   		return csum;
>   	skb_set_network_header(skb, ETH_HLEN);
> -	if ((ip_hdr(skb)->protocol != IPPROTO_UDP) ||
> -	    (skb->len < (ETH_HLEN +
> -			(ip_hdr(skb)->ihl << 2) +
> -			sizeof(struct udphdr)))) {
> +
> +	if (ip_hdr(skb)->protocol != IPPROTO_UDP ||
> +	    skb->len < (ETH_HLEN + ip_hdrlen(skb) + sizeof(struct udphdr))) {
>   		skb_reset_network_header(skb);
>   		return csum;
>   	}
> -	skb_set_transport_header(skb,
> -			ETH_HLEN + (ip_hdr(skb)->ihl << 2));
> +	skb_set_transport_header(skb, ETH_HLEN + ip_hdrlen(skb));
>   	csum = udp_hdr(skb)->check;
>   	skb_reset_transport_header(skb);
>   	skb_reset_network_header(skb);