On Mon, May 14, 2018 at 10:33 PM, Tobin C. Harding <to...@apporbit.com> wrote:
> On Mon, May 14, 2018 at 04:54:36PM -0700, William Tu wrote:
>> Before the patch, the erspan BSO bit (Bad/Short/Oversized) is not
>> handled. BSO has 4 possible values:
>> 00 --> Good frame with no error, or unknown integrity
>> 11 --> Payload is a Bad Frame with CRC or Alignment Error
>> 01 --> Payload is a Short Frame
>> 10 --> Payload is an Oversized Frame
>>
>> Based the short/oversized definitions in RFC1757, the patch sets
>> the bso bit based on the mirrored packet's size.
>>
>> Reported-by: Xiaoyan Jin <xiaoy...@vmware.com>
>> Signed-off-by: William Tu <u9012...@gmail.com>
>> ---
>> include/net/erspan.h | 25 +++++++++++++++++++++++++
>> 1 file changed, 25 insertions(+)
>>
>> diff --git a/include/net/erspan.h b/include/net/erspan.h
>> index d044aa60cc76..5eb95f78ad45 100644
>> --- a/include/net/erspan.h
>> +++ b/include/net/erspan.h
>> @@ -219,6 +219,30 @@ static inline __be32 erspan_get_timestamp(void)
>> return htonl((u32)h_usecs);
>> }
>>
>> +/* ERSPAN BSO (Bad/Short/Oversized)
>> + * 00b --> Good frame with no error, or unknown integrity
>> + * 01b --> Payload is a Short Frame
>> + * 10b --> Payload is an Oversized Frame
>> + * 11b --> Payload is a Bad Frame with CRC or Alignment Error
>> + */
>> +enum erspan_bso {
>> + BSO_NOERROR,
>> + BSO_SHORT,
>> + BSO_OVERSIZED,
>> + BSO_BAD,
>> +};
>
> If we are relying on the values perhaps this would be clearer
>
> BSO_NOERROR = 0x00,
> BSO_SHORT = 0x01,
> BSO_OVERSIZED = 0x02,
> BSO_BAD = 0x03,
>
Yes, thanks. I will change in v2.
>> +
>> +static inline u8 erspan_detect_bso(struct sk_buff *skb)
>> +{
>> + if (skb->len < ETH_ZLEN)
>> + return BSO_SHORT;
>> +
>> + if (skb->len > ETH_FRAME_LEN)
>> + return BSO_OVERSIZED;
>> +
>> + return BSO_NOERROR;
>> +}
>
> Without having much contextual knowledge around this patch; should we be
> doing some check on CRC or alignment (at some stage)? Having BSO_BAD
> seems to imply so?
>
The definition of BSO_BAD:
etherStatsCRCAlignErrors OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The total number of packets received that
had a length (excluding framing bits, but
including FCS octets) of between 64 and 1518
octets, inclusive, but but had either a bad
Frame Check Sequence (FCS) with an integral
number of octets (FCS Error) or a bad FCS with
a non-integral number of octets (Alignment Error)."
But I don't know how to check CRC error at this code point.
Isn't it done by the NIC hardware?
Thanks for your review!
William
