On Sat, Aug 11, 2007 at 08:54:46AM +0800, Herbert Xu wrote:
> Chris Snook <[email protected]> wrote:
> >
> > cpu_relax() contains a barrier, so it should do the right thing. For
> > non-smp architectures, I'm concerned about interacting with interrupt
> > handlers. Some drivers do use atomic_* operations.
>
> What problems with interrupt handlers? Access to int/long must
> be atomic or we're in big trouble anyway.
Reordering due to compiler optimizations. CPU reordering does not
affect interactions with interrupt handlers on a given CPU, but
reordering due to compiler code-movement optimization does. Since
volatile can in some cases suppress code-movement optimizations,
it can affect interactions with interrupt handlers.
Thanx, Paul
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