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    SubjectRe: [PATCH 14/21] cpuidle: coupled: don't compare cpu masks unnecessarily
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    On Sat, Sep 21, 2013 at 6:21 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
    > In cpuidle_coupled_register_device() we do following:
    > if (WARN_ON(!cpumask_equal(&dev->coupled_cpus, &coupled->coupled_cpus)))
    > coupled->prevent++;
    >
    > This is only required to be done when we are using 'coupled' from an existing
    > cpuidle_device and not when we have just done this:
    >
    > coupled->coupled_cpus = dev->coupled_cpus
    >
    > So, move this compare statement to the right place.
    >
    > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

    I don't agree with this. This patch is a tiny optimization in code
    that is rarely called, and it moves a final sanity check somewhere
    that it might get missed if the code were later refactored.

    > ---
    > drivers/cpuidle/coupled.c | 7 ++++---
    > 1 file changed, 4 insertions(+), 3 deletions(-)
    >
    > diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
    > index e952936..19a89eb 100644
    > --- a/drivers/cpuidle/coupled.c
    > +++ b/drivers/cpuidle/coupled.c
    > @@ -642,6 +642,10 @@ int cpuidle_coupled_register_device(struct cpuidle_device *dev)
    > other_dev = per_cpu(cpuidle_devices, cpu);
    > if (other_dev && other_dev->coupled) {
    > coupled = other_dev->coupled;
    > +
    > + if (WARN_ON(!cpumask_equal(&dev->coupled_cpus,
    > + &coupled->coupled_cpus)))
    > + coupled->prevent++;
    > goto have_coupled;
    > }
    > }
    > @@ -655,9 +659,6 @@ int cpuidle_coupled_register_device(struct cpuidle_device *dev)
    >
    > have_coupled:
    > dev->coupled = coupled;
    > - if (WARN_ON(!cpumask_equal(&dev->coupled_cpus, &coupled->coupled_cpus)))
    > - coupled->prevent++;
    > -
    > cpuidle_coupled_update_online_cpus(coupled);
    >
    > coupled->refcnt++;
    > --
    > 1.7.12.rc2.18.g61b472e
    >
    > --
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