linux-kernel - Re: [PATCH 0/7] Silence even more W=2 warnings

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Message-ID: <20140925082701.GC22317@nazgul.tnic>
Date:	Thu, 25 Sep 2014 10:27:01 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Rustad, Mark D" <mark.d.rustad@...el.com>
Cc:	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"sparse@...isli.org" <sparse@...isli.org>,
	"linux-sparse@...r.kernel.org" <linux-sparse@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/7] Silence even more W=2 warnings

On Tue, Sep 23, 2014 at 08:43:17PM +0000, Rustad, Mark D wrote:
> Well, please consider the specifics. The entire syscall table is initialized
> with a constant pattern to be sure that every item is initialized. Then each
> syscall is initialized into its proper place. The compiler is complaining that
> entries are being initialized twice.
> 
> Most of the time, that is not done, and so it may catch a patch foulup or
> something. In this particular case, it is normal and intended. There is
> nothing wrong, so there is no reason to throw a warning for every single
> entry in the table. Which is what happens with clang today.
> 
> So the code is correct, but in general the warning can reveal certain issues.
> Just not in this particular usage. This happens to be a warning specific to
> clang at the moment.

Well, I read this as clang is wrong. It looks like the compiler is
unable to understand a perfectly valid usage so it throws a warning. If
we go and fix it in the kernel, we'll be wagging the dog, so to speak.
Which is a no-no obviously.

> That is why it would be more than reasonable for checkpatch to warn on the
> macro introductions. It is certainly a more significant thing than a
> line > 80 characters.

No sorry - I don't agree here. So now you're proposing of adding the
macros *and* checkpatch to warn about them. That's a really wrong thing
to do on so many levels.

...

> Most of the time, it is new instances of warnings that are most likely to
> reveal a problem. Hiding them in a flood of "normal" warnings prevents
> them from ever being seen. And that is a shame.

Sorry, I can only suggest grepping here and also using what Geert
suggested. There's simply no justification IMO to add code to the kernel
for solely silencing warnings.

-- 
Regards/Gruss,
    Boris.
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