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    SubjectRe: [RFC patch 08/18] cnt32_to_63 should use smp_rmb()
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    Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

    > Assume the time source is a global clock which insures that time will never
    > *ever* go backward. Use a smp_rmb() to make sure the cnt_lo value is read before
    > __m_cnt_hi.

    If you have an smp_rmb(), then don't you need an smp_wmb()/smp_mb() to match
    it to make it work? And is your assumption valid that smp_rmb() will affect
    memory vs the I/O access to read the clock? There's no requirement that
    cnt_lo will have been read from an MMIO location at all.

    David


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