[PATCH v3] net: ethernet: use ip_hdrlen() instead of bit shift

[PATCH v3] net: ethernet: use ip_hdrlen() instead of bit shift

[Moon Yeounsu]

`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@gmail.com>
---
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);
-- 
2.45.2

Re: [PATCH v3] net: ethernet: use ip_hdrlen() instead of bit shift

[Christophe JAILLET]

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@gmail.com>

Reviewed-by: Christophe JAILLET <christophe.jaillet@wanadoo.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);

Re: [PATCH v3] net: ethernet: use ip_hdrlen() instead of bit shift

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Wed,  7 Aug 2024 19:07:21 +0900 you wrote:
> `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@gmail.com>
> 
> [...]

Here is the summary with links:
  - [v3] net: ethernet: use ip_hdrlen() instead of bit shift
    https://git.kernel.org/netdev/net/c/9a039eeb71a4

You are awesome, thank you!
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