Messages in this thread | | | Date | Mon, 10 Sep 2007 11:59:29 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures |
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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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