netdev - Re: [PATCH 1/4] sctp: Fix crc32c calculations on big-endian arhes.

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Date:	Fri, 23 Jan 2009 20:24:49 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Vlad Yasevich <vladislav.yasevich@...com>
Cc:	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	davem@...emloft.net
Subject: Re: [PATCH 1/4] sctp: Fix crc32c calculations on big-endian arhes.

On Fri, Jan 23, 2009 at 04:28:49PM +1100, Herbert Xu wrote:
>
> > > static inline __be32 sctp_end_cksum(__be32 crc32)
> > > {
> > > -       return ~crc32;
> > > +       return (__force __be32)~cpu_to_le32((__force u32)crc32);
> > > }
> > 
> > Ouch, surely there is a better way to do this?
> 
> In fact this looks wrong.  Has this code actually been tested
> on big-endian?

Reading this again it does seem to do the right thing as it's
using the raw crc32c interface as opposed to crypto crc32c.

However, I suggest that we change it as follows:

1) Make sh->csum __le32 since we're using crc32c_le.
2) Change all intermediate values in sctp/checksum.h to u32.
3) Make sctp_end_cksum return __le32 and have it do

	return cpu_to_le32(~crc);

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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