Re: [PATCH 24/27] Convert gfp_zone() to use a table of precalculatedvalues

[Christoph Lameter]

On Thu, 19 Mar 2009, Mel Gorman wrote:

> I ran into exactly that problem and ended up shoving the table into
> page_alloc.c but then there is no benefits from having the table statically
> declared because there is no constant folding.

Right. The table must be defined in the .h file. Just a matter of figuring
out how to convince the compiler/linker to do the right thing.

> > +	if (__builtin_constant_p(zone))
> > +		BUILD_BUG_ON(zone == BAD_ZONE);
> > +#ifdef CONFIG_DEBUG_VM
> > +	else
> > +		BUG_ON(zone == BAD_ZONE);
> >  #endif
>
> That could be made a bit prettier with
>
> 	if (__builtin_constant_p(zone))
> 		BUILD_BUG_ON(zone == BAD_ZONE);
> 	VM_BUG_ON(zone == BAD_ZONE);

VM_BUG_ON is not available here. It has to be that ugly.
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