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Subject: Re: [PATCH 1/7] Introduce the pagetable_operations and associated
	helper macros.
From: Dave Hansen <hansendc@us.ibm.com>
To: Adam Litke <agl@us.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Arjan van de Ven <arjan@infradead.org>,
       William Lee Irwin III <wli@holomorphy.com>,
       Christoph Hellwig <hch@infradead.org>, Ken Chen <kenchen@google.com>,
       linux-mm@kvack.org, linux-kernel@vger.kernel.org
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Date: Tue, 20 Mar 2007 16:24:41 -0700
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On Mon, 2007-03-19 at 13:05 -0700, Adam Litke wrote:
> 
> +#define has_pt_op(vma, op) \
> +       ((vma)->pagetable_ops && (vma)->pagetable_ops->op)
> +#define pt_op(vma, call) \
> +       ((vma)->pagetable_ops->call) 

Can you get rid of these macros?  I think they make it a wee bit harder
to read.  My brain doesn't properly parse the foo(arg)(bar) syntax.  

+       if (has_pt_op(vma, copy_vma))
+               return pt_op(vma, copy_vma)(dst_mm, src_mm, vma);

+       if (vma->pagetable_ops && vma->pagetable_ops->copy_vma)
+               return vma->pagetable_ops->copy_vma(dst_mm, src_mm, vma);

I guess it does lead to some longish lines.  Does it start looking
really nasty?

If you're going to have them, it might just be best to put a single
unlikely() around the macro definitions themselves to keep anybody from
having to open-code it for any of the users.  

-- Dave