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Re: [Xen-devel] [PATCH v2] introduce and use relaxed cpumask bitops

On Wed, 2015-02-11 at 13:42 +0000, Jan Beulich wrote:
> Using atomic (LOCKed on x86) bitops for certain of the operations on
> cpumask_t is overkill when the variables aren't concurrently accessible
> (e.g. local function variables, or due to explicit locking). Introduce
> alternatives using non-atomic bitops and use them where appropriate.
> Note that this
> - adds a volatile qualifier to cpumask_test_and_{clear,set}_cpu()
>   (should have been there from the beginning, like is the case for
>   cpumask_{clear,set}_cpu())
> - replaces several cpumask_clear()+cpumask_set_cpu(, n) pairs by the
>   simpler cpumask_copy(, cpumask_of(n)) (or just cpumask_of(n) if we
>   can do without copying)
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

AIUI there is no need for any arm changes (you reuse the existing
__clear_bit etc), so:
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

I suppose at some point we might want to switch xen/arch/arm to use the
relaxed ops where appropriate, but no need for you to worry about that.


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