Re: [GIT PULL -tip] fix 41 'make headers_check' warnings

[Sam Ravnborg <sam@ravnborg.org>]

On Sun, Jan 18, 2009 at 12:02:21PM +0100, Ingo Molnar wrote:
> 
> * Jaswinder Singh Rajput <jaswinder@kernel.org> wrote:
> 
> > diff --git a/include/linux/acct.h b/include/linux/acct.h
> > index 882dc72..a20c97c 100644
> > --- a/include/linux/acct.h
> > +++ b/include/linux/acct.h
> > @@ -59,9 +59,13 @@ struct acct
> >  	comp_t		ac_majflt;		/* Major Pagefaults */
> >  	comp_t		ac_swaps;		/* Number of Swaps */
> >  /* m68k had no padding here. */
> > -#if !defined(CONFIG_M68K) || !defined(__KERNEL__)
> > +#ifdef __KERNEL__
> > +#ifndef CONFIG_M68K
> >  	__u16		ac_ahz;			/* AHZ */
> > -#endif
> > +#endif /* CONFIG_M68K */
> > +#else /* __KERNEL__ */
> > +	__u16		ac_ahz;			/* AHZ */
> > +#endif /* __KERNEL__ */
> 
> that looks rather ugly.
> 
> Why not just flip it around to:
> 
> 	#if !defined(__KERNEL__) || !defined(CONFIG_M68K)
> 
> ? Does headers_check misinterpret that?

The original expression is misinterpreted by headers_check
because we want the ac_ahz to stay if either of __KERNEL__
or CONFIG_M68K is not defined.
And unifdef does not optimize away the !defined(CONFIG_M68K)
part - it has no knowledge that this is kernel internal.

So I am happy with Jaswinder's patch.

That said I really no not understand why there is this
subtle issue with struct acct in the first place..

	Sam