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    SubjectRe: [PATCH 0/24] make atomic_read() behave consistently across all architectures
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    On Fri, 2007-08-17 at 12:50 -0600, Chris Friesen wrote:
    > Linus Torvalds wrote:
    >
    > > - in other words, the *only* possible meaning for "volatile" is a purely
    > > single-CPU meaning. And if you only have a single CPU involved in the
    > > process, the "volatile" is by definition pointless (because even
    > > without a volatile, the compiler is required to make the C code appear
    > > consistent as far as a single CPU is concerned).
    >
    > I assume you mean "except for IO-related code and 'random' values like
    > jiffies" as you mention later on? I assume other values set in
    > interrupt handlers would count as "random" from a volatility perspective?
    >
    > > So anybody who argues for "volatile" fixing bugs is fundamentally
    > > incorrect. It does NO SUCH THING. By arguing that, such people only show
    > > that you have no idea what they are talking about.
    >
    > What about reading values modified in interrupt handlers, as in your
    > "random" case? Or is this a bug where the user of atomic_read() is
    > invalidly expecting a read each time it is called?

    the interrupt handler case is an SMP case since you do not know
    beforehand what cpu your interrupt handler will run on.



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