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

[David Howells]

Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> > I use smp_rmb() to do this on SMP systems (hrm, actually, a rmb() could
> > be required so it works also on UP systems safely wrt interrupts).
> 
> smp_rmb turns into a compiler barrier on UP and should prevent the below
> description.

Note that that does not guarantee that the two reads will be done in the order
you want.  The compiler barrier _only_ affects the compiler.  It does not stop
the CPU from doing the reads in any order it wants.  You need something
stronger than smp_rmb() if you need the reads to be so ordered.

David
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