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

[Peter Zijlstra]

On Mon, 2011-02-14 at 12:29 -0500, Mike Frysinger wrote:
> On Mon, Feb 14, 2011 at 12:27, Peter Zijlstra wrote:
> > On Mon, 2011-02-14 at 12:18 -0500, Steven Rostedt wrote:
> >> blackfin, seems to be doing quite a lot. Not sure if it is required, but
> >> that may need a bit of investigating to understand why it does the
> >> raw_uncached thing.
> >
> > From what I can tell its flushing its write cache, invalidating its
> > d-cache and then issue the read, something which is _way_ overboard.
> 
> not when the cores in a SMP system lack cache coherency

But atomic_read() is completely unordered, so even on a non-coherent
system a regular read should suffice, any old value is correct.

The only problem would be when you could get cache aliasing and read
something totally unrelated.

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