Re: [PATCH] FRV: Fix the section attribute on UP DECLARE_PER_CPU()

[David Howells <dhowells@redhat.com>]

Linus Torvalds <torvalds@linux-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