Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

[Christoph Lameter <clameter@sgi.com>]

On Fri, 17 Aug 2007, Segher Boessenkool wrote:

> "volatile" has nothing to do with reordering.  atomic_dec() writes
> to memory, so it _does_ have "volatile semantics", implicitly, as
> long as the compiler cannot optimise the atomic variable away
> completely -- any store counts as a side effect.

Stores can be reordered. Only x86 has (mostly) implicit write ordering. So 
no atomic_dec has no volatile semantics and may be reordered on a variety 
of processors. Writes to memory may not follow code order on several 
processors.


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