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Subject: Re: 2.6.23-rc4-mm1 compile error for ppc 32
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       linux-kernel@vger.kernel.org
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Date: Sat, 08 Sep 2007 18:42:10 +0200
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> > If so, the finger points at this:
> >
> > static __inline__ void __clear_bit_unlock(int nr, volatile unsigned long
> > *addr) {
> > 	__asm__ __volatile__(LWSYNC_ON_SMP ::: "memory");
> > 	__clear_bit(nr, addr);
> > }
> >
> > which was added by Nick's powerpc-lock-bitops.patch.  I am suspecting that
> > this isn't pp32 code?
> 
> Hmm, when LWSYNC_ON_SMP is a noop, it seems like it should probably
> be an empty string instead of nothing? ("") That should make behaviour
> more consistent I think.

The wormhole is arch/ppc's hack to get to include/asm-powerpc...

As for having LWSYNC_ON_SMP be "" ... that might be the best way but I'd
rather not take chances right now and go for the quick fix of making
__clear_bit_unlock() do

	LWSYNC_ON_SMP ""

instead.

Ben.