linux-kernel - Re: [PATCH 01/21] powerpc: Remove warning on array size when empty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180227204243.GW21977@gate.crashing.org>
Date:   Tue, 27 Feb 2018 14:42:43 -0600
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Mathieu Malaterre <malat@...ian.org>,
        "open list:LINUX FOR POWERPC PA SEMI PWRFICIENT" 
        <linuxppc-dev@...ts.ozlabs.org>, Paul Mackerras <paulus@...ba.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jiri Slaby <jslaby@...e.com>
Subject: Re: [PATCH 01/21] powerpc: Remove warning on array size when empty

On Tue, Feb 27, 2018 at 05:52:06PM +0200, Andy Shevchenko wrote:
> On Tue, Feb 27, 2018 at 9:44 AM, Mathieu Malaterre <malat@...ian.org> wrote:
> > On Tue, Feb 27, 2018 at 8:33 AM, Christophe LEROY
> > <christophe.leroy@....fr> wrote:
> 
> >>>>> Much simpler is just add
> >>>>>
> >>>>> if (ARRAY_SIZE() == 0)
> >>>>>   return;
> 
> >> Or add in front:
> >> if (!ARRAY_SIZE(feature_properties))
> >>         return;
> >
> > (not tested) I believe the compiler still go over the for() loop and
> > will complain about the original unsigned comparison.
> 
> Did you run tests? Did you look into object file?
> 
> In kernel we much rely on the compiling away the code which is
> deterministically not in use.
> Here I'm pretty sure it will compile away entire function.

It does, but it also still warns (this warning is done very early in the
compiler pipeline).


Segher