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Date: Fri, 26 Sep 2008 08:03:02 -0400 (EDT)
From: Nicolas Pitre <nico@cam.org>
X-X-Sender: nico@xanadu.home
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Howells <dhowells@redhat.com>, torvalds@osdl.org,
       akpm@linux-foundation.org, linux-am33-list@redhat.com,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] MN10300: Move asm-arm/cnt32_to_63.h to include/linux/
In-reply-to: <1222426580.16700.258.camel@lappy.programming.kicks-ass.net>
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On Fri, 26 Sep 2008, Peter Zijlstra wrote:

> On Wed, 2008-09-24 at 17:48 +0100, David Howells wrote:
> > Move asm-arm/cnt32_to_63.h to include/linux/ so that MN10300 can make use of it
> > too.
> > 
> > Signed-off-by: David Howells <dhowells@redhat.com>
> > ---
> > 
> >  arch/arm/mach-pxa/time.c       |    2 +
> >  arch/arm/mach-sa1100/generic.c |    2 +
> >  arch/arm/mach-versatile/core.c |    2 +
> >  include/linux/cnt32_to_63.h    |   80 ++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 83 insertions(+), 3 deletions(-)
> >  create mode 100644 include/linux/cnt32_to_63.h
> 
> Didn't you forget to remove the old one?
> 
> 
> > +#define cnt32_to_63(cnt_lo) \
> > +({ \
> > +	static volatile u32 __m_cnt_hi; \
> > +	union cnt32_to_63 __x; \
> > +	__x.hi = __m_cnt_hi; \
> > +	__x.lo = (cnt_lo); \
> > +	if (unlikely((s32)(__x.hi ^ __x.lo) < 0)) \
> > +		__m_cnt_hi = __x.hi = (__x.hi ^ 0x80000000) + (__x.hi >> 31); \
> > +	__x.val; \
> > +})
> > +
> > +#endif
> 
> That code is way to smart :-)
> 
> Better make sure that non of its users are SMP capable though.

Why would that matter?


Nicolas