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SubjectRe: [linux-next][PATCH] revert headers_check fix: ia64, fpu.h
On Fri, Feb 06, 2009 at 05:33:14PM +0100, Ingo Molnar wrote:
>
> * Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
>
> > On Fri, Feb 06, 2009 at 05:12:29PM +0100, Ingo Molnar wrote:
> > >
> > > * Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> > >
> > > > > We cannot see any downside of this patch.
> > > > >
> > > > > But we can see upside of this patch is:
> > > > > 1. No need to protect linux/types.h with #ifndef __ASSEMBLY__ in many
> > > > > files
> > > > > 2. So we trying to replace multiple #ifndef __ASSEMBLY__ with one.
> > > >
> > > > The point is:
> > > >
> > > > 1. If the parent include needs to include linux/types.h to get at C
> > > > types _and_ the include file needs to also be included by assembly
> > > > code, it itself needs to have #ifndef __ASSEMBLY__ to protect those
> > > > uses from the assembly code.
> > > >
> > > > In that case, the linux/types.h include should be contained within
> > > > the #ifndef __ASSEMBLY__ .. #endif block along with all C only
> > > > parts of the header file.
> > >
> > > That makes the code much less clean: putting #include's in the middle of a
> > > header is poor style and leads to people failing to consider dependencies.
> > > We generally put them to the header portion.
> > >
> > > Putting an #include line in the middle of a header file is a receipe for a
> > > dependency hell (it can easily fall inside #ifdefs, can be overlooked,
> > > etc.), so it's _strongly_ discouraged (at least on arch/x86).
> >
> > Put them at the top then with an additional ifndef.
>
> So you advocate 40 stupid pairs of #ifdefs spread out, instead of a
> _single_, obvious #ifdef in a commonly used header?

As I see it, if you want all your style points to be adhered to, then yes.
And I do believe it to be a valid solution.

Personally, I'd put them nearer the C code.

That's precisely what I do with the ARM include files. Never been a
problem.


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