Re: [PATCH 0/2] jump label: 2.6.38 updates

[Peter Zijlstra]

On Mon, 2011-02-14 at 17:38 +0000, Will Newton wrote:
> On Mon, Feb 14, 2011 at 5:27 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> >> So all but a few have basically (as you said on IRC)
> >> #define atomic_read(v) ACCESS_ONCE(v)
> >
> > ACCESS_ONCE(v->counter), but yeah :-)
> 
> I maintain an out-of-tree architecture where that isn't the case
> unfortunately [1]. Not expecting any special favours for being
> out-of-tree of course, but just thought I would add that data point.
> 
> [1] Our atomic operations go around the cache rather than through it,
> so the value of an atomic cannot be read with a normal load
> instruction.

Cannot how? It would observe a stale value? That is acceptable for
atomic_read(). 

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