Subject: Re: SCTP checksum patch for 2.6.26.5

From: Vlad Yasevich <[email-masked]>
Date: Mon, 22 Sep 2008 16:36:58 -0400

David Miller wrote:
> From: Nickolay Vinogradov <[email-masked]>
> Date: Mon, 22 Sep 2008 19:58:26 +0400
> 
> CC:'ing correct mailing lists...
> 
>> SCTP checksum calculation fix for BigEndian.
>> ntohl() doesn't do anything on BigEndian.
>>
>> diff --git a/Makefile b/Makefile
>> diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
>> index ba75c67..2f0ed64 100644
>> --- a/include/net/sctp/checksum.h
>> +++ b/include/net/sctp/checksum.h
>> @@ -74,5 +74,19 @@ static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
>>
>>   static inline __u32 sctp_end_cksum(__u32 crc32)
>>   {
>> -       return ntohl(~crc32);
>> +       __u32 result;
>> +       __u8 byte0, byte1, byte2, byte3;
>> +
>> +       result = ~crc32;
>> +
>> +       byte0 = result & 0xff;
>> +       byte1 = (result>>8) & 0xff;
>> +       byte2 = (result>>16) & 0xff;
>> +       byte3 = (result>>24) & 0xff;
>> +
>> +       crc32 = ((byte0 << 24) |
>> +                (byte1 << 16) |
>> +                (byte2 << 8)  |
>> +                byte3);
>> +       return crc32;
>>   }
>> diff --git a/net/sctp/output.c b/net/sctp/output.c

Was this tested?  I remember running tests with that code between
big and little endian arches and it worked.  So, the old code worked
correclty.

I changed in 2.6.27 series to do all the calculations in network order anyway.

-vlad

>>
>>
>> -- Nickolay Vinogradov
>> Protei Research and Development Center
>> St.Petersburg, 194044, Russia
>> Tel.: +7 812 449 47 27
>> --
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