[Xen-devel] Re: [PATCH 2/3] mm: Add SECTION_ALIGN_UP() and SECTION_ALIGN_DOWN() macro

[Daniel Kiper <dkiper@xxxxxxxxxxxx>]

On Mon, Mar 28, 2011 at 08:41:24AM -0700, Dave Hansen wrote:
> On Mon, 2011-03-28 at 11:24 +0200, Daniel Kiper wrote:
> > Add SECTION_ALIGN_UP() and SECTION_ALIGN_DOWN() macro which aligns
> > given pfn to upper section and lower section boundary accordingly.
> >
> > Signed-off-by: Daniel Kiper <dkiper@xxxxxxxxxxxx>
> > ---
> >  include/linux/mmzone.h |    3 +++
> >  1 files changed, 3 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> > index 02ecb01..d342820 100644
> > --- a/include/linux/mmzone.h
> > +++ b/include/linux/mmzone.h
> > @@ -931,6 +931,9 @@ static inline unsigned long early_pfn_to_nid(unsigned 
> > long pfn)
> >  #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
> >  #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
> >
> > +#define SECTION_ALIGN_UP(pfn)      (((pfn) + PAGES_PER_SECTION - 1) & 
> > PAGE_SECTION_MASK)
> > +#define SECTION_ALIGN_DOWN(pfn)    ((pfn) & PAGE_SECTION_MASK)
>
> There are certainly a lot of different ways to do this, including using
> the existing ALIGN() macro, but you won't be the first to open-code
> it. :)

Sorry, I forgot about ALIGN(). However, there is only up version available.
That is why I prefer open-code version here. It is clearer in both
cases what is going on.

Daniel

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