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    SubjectRe: [PATCH 3/3] cpufreq: Drop unnecessary cpus locking from store()
    On Thu, May 26, 2022 at 1:51 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
    >
    > This change was introduced long back by:
    >
    > commit 4f750c930822 ("cpufreq: Synchronize the cpufreq store_*() routines with CPU hotplug")
    >
    > Since then, both cpufreq and hotplug core have been reworked and have
    > much better locking in place. The race mentioned in commit 4f750c930822
    > isn't possible anymore.
    >
    > Drop the unnecessary locking.
    >
    > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    > ---
    > drivers/cpufreq/cpufreq.c | 19 ++++---------------
    > 1 file changed, 4 insertions(+), 15 deletions(-)
    >
    > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
    > index 53d163a84e06..bb237d1ce5e7 100644
    > --- a/drivers/cpufreq/cpufreq.c
    > +++ b/drivers/cpufreq/cpufreq.c
    > @@ -973,21 +973,10 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
    > if (!fattr->store)
    > return -EIO;
    >
    > - /*
    > - * cpus_read_trylock() is used here to work around a circular lock
    > - * dependency problem with respect to the cpufreq_register_driver().
    > - */
    > - if (!cpus_read_trylock())
    > - return -EBUSY;
    > -
    > - if (cpu_online(policy->cpu)) {
    > - down_write(&policy->rwsem);
    > - if (likely(!policy_is_inactive(policy)))
    > - ret = fattr->store(policy, buf, count);
    > - up_write(&policy->rwsem);
    > - }
    > -
    > - cpus_read_unlock();
    > + down_write(&policy->rwsem);
    > + if (likely(!policy_is_inactive(policy)))
    > + ret = fattr->store(policy, buf, count);
    > + up_write(&policy->rwsem);
    >
    > return ret;
    > }
    > --

    Applied along with the [1/3] as 5.20 material, thanks!

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