Re: [RFC patch 08/18] cnt32_to_63 should use smp_rmb()

[David Howells]

Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> 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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