[PATCH 2/2] Fix compile error of pgtable-ppc64.h

[Benjamin Herrenschmidt]

On Wed, 2014-01-29 at 10:45 -0800, Greg KH wrote:
> On Tue, Jan 28, 2014 at 05:52:42PM +0530, Aneesh Kumar K.V wrote:
> > From: Li Zhong <zhong at linux.vnet.ibm.com>
> > 
> > It seems that forward declaration couldn't work well with typedef, use
> > struct spinlock directly to avoiding following build errors:
> > 
> > In file included from include/linux/spinlock.h:81,
> >                  from include/linux/seqlock.h:35,
> >                  from include/linux/time.h:5,
> >                  from include/uapi/linux/timex.h:56,
> >                  from include/linux/timex.h:56,
> >                  from include/linux/sched.h:17,
> >                  from arch/powerpc/kernel/asm-offsets.c:17:
> > include/linux/spinlock_types.h:76: error: redefinition of typedef 'spinlock_t'
> > /root/linux-next/arch/powerpc/include/asm/pgtable-ppc64.h:563: note: previous declaration of 'spinlock_t' was here
> > 
> > build fix for upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f
> > for 3.13 stable series
> 
> I don't understand, why is this needed?  Is there a corrisponding patch
> upstream that already does this?  What went wrong with a "normal"
> backport of the patch to 3.13?

There's a corresponding patch in powerpc-next that I'm about to send to
Linus today, but for the backport, the "fix" could be folded into the
original offending patch.

Cheers,
Ben.