linux-kernel - Re: [net-next PATCH 11/11] net: ravb: Add VLAN checksum support

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Message-ID: <04de48d4-12dc-4dd9-a234-afd26be02561@omp.ru>
Date: Wed, 2 Oct 2024 18:27:58 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Simon Horman <horms@...nel.org>
CC: Paul Barker <paul@...rker.dev>, "David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
 Abeni <pabeni@...hat.com>, Paul Barker <paul.barker.ct@...renesas.com>, Geert
 Uytterhoeven <geert+renesas@...der.be>, Niklas Söderlund
	<niklas.soderlund+renesas@...natech.se>, Biju Das
	<biju.das.jz@...renesas.com>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>, <netdev@...r.kernel.org>,
	<linux-renesas-soc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [net-next PATCH 11/11] net: ravb: Add VLAN checksum support

On 10/1/24 13:44, Simon Horman wrote:
[...]

>>> From: Paul Barker <paul.barker.ct@...renesas.com>
>>>
>>> The GbEth IP supports offloading checksum calculation for VLAN-tagged
>>> packets, provided that the EtherType is 0x8100 and only one VLAN tag is
>>> present.
>>>
>>> Signed-off-by: Paul Barker <paul.barker.ct@...renesas.com>
>> [...]
>>
>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
>>> index 832132d44fb4..eb7499d42a9b 100644
>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>> @@ -2063,11 +2063,30 @@ static void ravb_tx_timeout_work(struct work_struct *work)
>>>  
>>>  static bool ravb_can_tx_csum_gbeth(struct sk_buff *skb)
>>>  {
>>> -	/* TODO: Need to add support for VLAN tag 802.1Q */
>>> -	if (skb_vlan_tag_present(skb))
>>> +	u16 net_protocol = ntohs(skb->protocol);
>>> +
>>> +	/* GbEth IP can calculate the checksum if:
>>> +	 * - there are zero or one VLAN headers with TPID=0x8100
>>> +	 * - the network protocol is IPv4 or IPv6
>>> +	 * - the transport protocol is TCP, UDP or ICMP
>>> +	 * - the packet is not fragmented
>>> +	 */
>>> +
>>> +	if (skb_vlan_tag_present(skb) &&
>>> +	    (skb->vlan_proto != ETH_P_8021Q || net_protocol == ETH_P_8021Q))
>>
>>    Not sure I understand this check... Maybe s/==/!=/?
> 
> A minor nit if the check stays in some form:
> vlan_proto is big endian, while ETH_P_8021Q is host byte order.

   Not minor at all, thanks for spotting!
   Luckily, we also have a kernel test robot which runs sparse. :-)

[...]

MBR, Sergey