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Message-ID: <14172.1239795632@redhat.com>
Date: Wed, 15 Apr 2009 12:40:32 +0100
From: David Howells <dhowells@...hat.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: dhowells@...hat.com, tj@...nel.org, mingo@...e.hu,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] FRV: Fix the section attribute on UP DECLARE_PER_CPU()
Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> But yeah, I didn't look at all the details. It _looked_ pretty
> straightforward to just move the DEFINE/DECLARE stuff up, but there may well
> be something subtle I'm missing.
The problem is mainly one of #include recursion. There's way too much of it.
I wonder if we should replace the standard headerfile boilerplate:
#ifndef _THIS_HEADER_H
#define _THIS_HEADER_H
...
#endif /* _THIS_HEADER_H */
with something a bit nastier:
#ifndef _THIS_HEADER_H
#define _THIS_HEADER_H 1
...
#undef _THIS_HEADER_H
#define _THIS_HEADER_H 2
#elif _THIS_HEADER_H == 1
#error Recursive inclusion is not permitted
#endif /* _THIS_HEADER_H */
and make people break up their header files to avoid getting this error.
There are a number of problems with doing this, of course; the least of which
is that cpp has special code for handling the first case efficiently, IIRC.
David
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