linux-kernel - Re: Why is the kfree() argument const?

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Message-ID: <87ir1tcs8f.fsf@saeurebad.de>
Date:	Wed, 16 Jan 2008 23:37:04 +0100
From:	Johannes Weiner <hannes@...urebad.de>
To:	Christoph Lameter <clameter@....com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	penberg@...helsinki.fi
Subject: Re: Why is the kfree() argument const?

Hi,

Christoph Lameter <clameter@....com> writes:

> On Wed, 16 Jan 2008, Johannes Weiner wrote:
>
>> So if I got it right and you actually modify the memory you only got a
>> const pointer to, you reach a level where you _have to_ break this
>> policy and cast to a non-const pointer, as it is currently done in
>> kfree().  No?
>
> Correct and we have gcc 4.2 currently spitting out warnings because of 
> casting to non const. Any idea how to convince gcc that this is okay?

Two dirty hacks where gcc at least does not complain:

	void *y = (void *)x;

and then pass y, or passing

	*(void **)&x

directly.

Both approaches seem just too ugly to silence a bogus warning.

	Hannes
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