From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willy Tarreau Subject: Re: SCTP checksum patch for 2.6.26.5 Date: Tue, 23 Sep 2008 07:19:20 +0200 Message-ID: <20080923051920.GD24654@1wt.eu> References: <48D7C0A2.9090406@protei.ru> <20080922.131245.193705447.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: nickolay@protei.ru, linux-kernel@vger.kernel.org, linux-sctp@vger.kernel.org, netdev@vger.kernel.org To: David Miller Return-path: Received: from 1wt.eu ([62.212.114.60]:4441 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751465AbYIWFTh (ORCPT ); Tue, 23 Sep 2008 01:19:37 -0400 Content-Disposition: inline In-Reply-To: <20080922.131245.193705447.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Sep 22, 2008 at 01:12:45PM -0700, David Miller wrote: > From: Nickolay Vinogradov > 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; > > } Nickolay, you should use swab32(~crc32) instead. It will make use of arch-specific optimisations when available (eg: bswap on x86). Willy