linux-kernel - Re: [RFC] x86: merge nmi

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Date:	Sat, 17 May 2008 23:40:21 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
cc:	Tom Spink <tspink@...il.com>, Cyrill Gorcunov <gorcunov@...il.com>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Slaby <jirislaby@...il.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [RFC] x86: merge nmi_32-64 to nmi.c

On Sat, 17 May 2008, Maciej W. Rozycki wrote:
> On Sat, 17 May 2008, Tom Spink wrote:
> 
> > static inline unsigned int get_nmi_count(int cpu)
> > {
> > #ifdef CONFIG_X86_64
> >         return cpu_pda(cpu)->__nmi_count;
> > #else
> >         return nmi_count(cpu);
> > #endif
> > }
> > 
> > I know it introduces a lot of these conditionals, but at least there
> > is one place to look for the get_nmi_count function, instead of
> > searching for all variants of the function.
> 
>  Well, I suppose some header should provide a definition like:
> 
> #ifdef CONFIG_X86_64
> #define cpu_x86_64 1
> #else
> #define cpu_x86_64 0
> #endif
> 
> and the you can remove the horrible #ifdef clutter and make the quoted 
> function look like:
> 
> static inline unsigned int get_nmi_count(int cpu)
> {
> 	return cpu_x86_64 ? cpu_pda(cpu)->__nmi_count : nmi_count(cpu);
> }
> 
> Much better -- isn't it?

Definitely, but we should do it at the Kconfig level which allows us
to have integer defines as well, so we end up with something like:

static inline unsigned int get_nmi_count(int cpu)
{
      return CONFIG_X86_64 ? cpu_pda(cpu)->__nmi_count : nmi_count(cpu);
}

That way we do not even have to think about which header to select for
the include and the association of the selector is stronger than the
cpu_x86_64 one, isn't it ?

Thanks,
	tglx
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