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    SubjectRe: [PATCH] make atomic_t volatile on all architectures


    On Wed, 8 Aug 2007, Chris Snook wrote:
    >
    > Some architectures currently do not declare the contents of an atomic_t to be
    > volatile. This causes confusion since atomic_read() might not actually read
    > anything if an optimizing compiler re-uses a value stored in a register, which
    > can break code that loops until something external changes the value of an
    > atomic_t.

    I'd be *much* happier with "atomic_read()" doing the "volatile" instead.

    The fact is, volatile on data structures is a bug. It's a wart in the C
    language. It shouldn't be used.

    Volatile accesses in *code* can be ok, and if we have "atomic_read()"
    expand to a "*(volatile int *)&(x)->value", then I'd be ok with that.

    But marking data structures volatile just makes the compiler screw up
    totally, and makes code for initialization sequences etc much worse.

    Linus
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