From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Schillstrom Subject: Re: [PATCH] netfilter: xt_HMARK: endian bugs Date: Mon, 14 May 2012 19:51:34 +0200 Message-ID: <201205141951.36692.hans.schillstrom@ericsson.com> References: <1337002943-16374-1-git-send-email-hans.schillstrom@ericsson.com> <201205141809.18174.hans.schillstrom@ericsson.com> <1337012674.8512.589.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Jan Engelhardt , Pablo Neira Ayuso , "kaber@trash.net" , "jengelh@medozas.de" , "netfilter-devel@vger.kernel.org" , "netdev@vger.kernel.org" , "dan.carpenter@oracle.com" , "hans@schillstrom.com" To: Eric Dumazet Return-path: In-Reply-To: <1337012674.8512.589.camel@edumazet-glaptop> Content-Disposition: inline Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Monday 14 May 2012 18:24:34 Eric Dumazet wrote: > On Mon, 2012-05-14 at 18:09 +0200, Hans Schillstrom wrote: > > > This context can contain both le & be machines, > > so at least in hmark it make sense > > Before jhash() and its shuffle ? What do you mean ? I want that a Big endian machine should produce the same hash value independent of flow direction as a Little endian. OK, I missed ntohl() before calling jhash_3words() Correct me if I'm wrong here (have no big endian machine available for test) jhash_3words() and __jhash_final() seems to be "endian" safe. So by doing the expensive ntohl on addresses and ports into jhash_3words() it will produce the same value on both be and le. That's why I want to have the ntohs() / ntohl() when comparing. > > Please respin your patch using (__force u16/u32) instead of > useless/expensive ntohs() / ntohl() (in _this_ context of hashing) > > If you compare two 32bits values, of course they must have same > ordering, but seeding jhash() is another matter. > > (Granted all calls use the same ordering of course) > > sparse is great tool, but if you add useless ntohl() calls to make > sparse silent, then its probably better to not use sparse. >