Re: [BUG FIX] Make x86_32 uni-processor Atomic ops, Atomic

["Michael S. Zick" <lkml@morethan.org>]

On Fri May 22 2009, H. Peter Anvin wrote:
> Ingo Molnar wrote:
> > * Michael S. Zick <lkml@morethan.org> wrote:
> > 
> >> Found in the bit-rot for 32-bit, x86, Uni-processor builds:
> >>
> >> diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
> >> index f6aa18e..3c790ef 100644
> >> --- a/arch/x86/include/asm/alternative.h
> >> +++ b/arch/x86/include/asm/alternative.h
> >> @@ -35,7 +35,7 @@
> >>                 "661:\n\tlock; "
> >>
> >>  #else /* ! CONFIG_SMP */
> >> -#define LOCK_PREFIX ""
> >> +#define LOCK_PREFIX "\n\tlock; "
> >>  #endif
> > 
> > What is your motivation for this change? At first sight this makes 
> > the UP kernel a bit larger and a bit smaller. Are you fixing some 
> > real regression/bug here?
> > 
> 
> That looks very odd indeed.  The whole point of the LOCK_PREFIX macro is
> to squelch it on UP (locks that should not be squelched on UP should not
> be annotated LOCK_PREFIX.)
> 

OK, will inspect for that possibility.
We may just have a mis-use of LOCK_PREFIX.

Mike
> 	-hpa
> 
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