Re: [net-next PATCH 05/11] net: ravb: Simplify types in RX csum validation

Paul Barker
2024-10-03T09:23:42Z

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On 30/09/2024 20:11, Sergey Shtylyov wrote:
> On 9/30/24 19:08, Paul Barker wrote:
>
>> From: Paul Barker <paul.barker.ct@bp.renesas.com>
>>
>> The HW checksum value is used as a 16-bit flag, it is zero when the
>
> I think I prefer s/HW/hardware/ but there's no hard feelings... :-)
>
>> checksum has been validated and non-zero otherwise. Therefore we don't
>> need to treat this as an actual __wsum type or call csum_unfold(), we
>> can just use a u16 pointer.
>>
>> Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
> [...]
>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
>> index 1dd2152734b0..9350ca10ab22 100644
>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> [...]
>> @@ -762,23 +761,22 @@ static void ravb_rx_csum_gbeth(struct sk_buff *skb)
>> * The last 2 bytes are the protocol checksum status which will be zero
>> * if the checksum has been validated.
>> */
>> - if (unlikely(skb->len < sizeof(__sum16) * 2))
>> + csum_len = sizeof(*hw_csum) * 2;
>
> Could've been done by an initializer instead?

So, if I move this to the initializers at the start of the function,
csum_len must be declared after hw_csum which breaks reverse Christmas
tree ordering:

struct skb_shared_info *shinfo = skb_shinfo(skb);
u16 *hw_csum;
size_t csum_len = sizeof(*hw_csum) * 2;

Thanks,

--
Paul Barker

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