Re: Memory barriers and spin_unlock safety

[Linus Torvalds]

On Fri, 3 Mar 2006, David Howells wrote:
> 
> I suspect, then, that x86_64 should not have an SFENCE for smp_wmb(), and that
> only io_wmb() should have that.

Indeed. I think smp_wmb() should be a compiler fence only on x86(-64), ie 
just compile to a "barrier()" (and not even that on UP, of course).

		Linus
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