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Message-ID: <4CD9B3DD.8090603@yahoo.fr>
Date: Tue, 09 Nov 2010 21:49:33 +0100
From: Lionel Debroux <lionel_debroux@yahoo.fr>
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To: Kees Cook <kees.cook@canonical.com>
CC: David Daney <ddaney@caviumnetworks.com>, linux-kernel@vger.kernel.org,
        Andy Whitcroft <apw@canonical.com>
Subject: Re: [linux-next] automatic use of checkpatch.pl for security?
References: <20101109173357.GA5876@outflux.net> <4CD9887E.3040607@caviumnetworks.com> <20101109175921.GD5876@outflux.net>
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Hi,

On 09.11.2010 18:59, Kees Cook wrote:
> Hi David,
> On Tue, Nov 09, 2010 at 09:44:30AM -0800, David Daney wrote:
> > On 11/09/2010 09:33 AM, Kees Cook wrote:
> > > In an effort to continue the constification work, it'd be nice to
> > > not accidentally introduce regressions or add additional work.
> > > Since checkpatch.pl already knows to warn about a lot of things
> > > including const structures, it would be great to have all commits
> > > going through linux-next (or something) have to pass at least a
> > > subset of checkpatch.pl's checks.
> > >
> > > For example, Lionel Debroux pointed out to me that looking at the
> > > last 1000 commits, there are a lot of warnings, including things
> > > like:
> > >
> > > WARNING: struct dma_map_ops should normally be const
> > > #499: FILE: arch/mips/mm/dma-default.c:301:
> > > +static struct dma_map_ops mips_default_dma_map_ops = {
> > >
> > > Can we add some kind of automatic checking to actually give
> > > checkpatch.pl some real teeth for at least some of its checks?
> > >
> >
> > Ok, did you actually try to make it const as suggested?  If you
> > had, you would have found that there are declarations throughout
> > the code base that conflict with checkpatch.pl's suggestion.
> >
> > There are several things we could do:
> >
> > 1) Force people to clean up the entire kernel tree before making
> > trivial changes that checkpatch.pl might complain about.
> >
> > 2) Change checkpatch.pl so that it doesn't complain about this.
> >
> > 3) Make reasonable changes and ignore the checkpatch.pl warning.
> >
> >
> > In that specific case you cite, #3 was chosen.
> 
> Right, I don't want to suggest unreasonable changes; I want to try
> and start a discussion about what might make a good addition to
> help avoid obvious problems. (The chosen example was, perhaps, not
> a good one.)
My bad, sorry.
backlight_ops and platform_suspend_ops, for which I sent patches to
linux-janitors, may be better examples: several new static mutable
instances of those structs have been added after
79404849e90a41ea2109bd0e2f7c7164b0c4ce73, which adds backlight_ops,
platform_suspend_ops and others to the list of "should be const" structures.
backlight_device_register() has been taking a "const struct
backlight_ops *ops" argument since
9905a43b2d563e6f89e4c63c4278ada03f2ebb14, nearly 11 months ago.

> > If you gate admission to linux-next with some sort of automated
> > check like this, I fear the wrath of the disgruntled masses may
> > fall upon you.
> But it seems like it might be nice to do at least something there?
I think so, in order to help janitorial work.


Lionel.
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