Re: [GIT RFC] percpu: use dynamic percpu allocator as the defaultpercpu allocator

[Martin Schwidefsky]

On Wed, 25 Mar 2009 20:51:31 +0900
Tejun Heo <tj@xxxxxxxxxx> wrote:

> > With your patches and a RELOC_HIDE version that uses the GOTENT
> > indirection the kernel won't compile because the "X" constraint for
> > the GOTENT access needs a symbol and there are quite a few users that
> > pass a pointer. I do not see a simple solution for that problem yet.
> 
> Ah... okay.  Now I get it.  It wasn't expecting variables there.  How
> about doing the following?
> 
>  #define SHIFT_PERCPU_PTR(ptr, offset) (({				\
> 	 if (__builtin_constant_p(ptr))					\
> 		 do GOTENT trick;					\
> 	 else								\
> 		 RELOC_HIDE();						\
>  }))

That doesn't work because __builtin_constant_p is false for variable
symbols. I would need a __builtin_symbol_p but that doesn't exist.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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