Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Fri, 15 Jul 2022 19:20:55 +0200 | Subject | Re: [PATCH V3] cpufreq: Warn users while freeing active policy |
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On Thu, Jul 7, 2022 at 11:58 AM Viresh Kumar <viresh.kumar@linaro.org> wrote: > > With the new design in place, the show() and store() callbacks check if > the policy is active or not before proceeding any further to avoid > potential races. And in order to guarantee that cpufreq_policy_free() > must be called after clearing the policy->cpus mask, i.e. by marking the > policy inactive. > > In order to avoid introducing a bug around this later, print a warning > message if we end up freeing an active policy. > > Also update cpufreq_online() a bit to make sure we clear the cpus mask > for each error case before calling cpufreq_policy_free(). > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > V3: BUG_ON() -> pr_warn() > > drivers/cpufreq/cpufreq.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 73432360e6e9..954eef26685f 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1273,6 +1273,13 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) > unsigned long flags; > int cpu; > > + /* > + * The callers must ensure the policy is inactive by now, to avoid any > + * races with show()/store() callbacks. > + */ > + if (unlikely(!policy_is_inactive(policy))) > + pr_warn("%s: Freeing active policy\n", __func__); > + > /* Remove policy from list */ > write_lock_irqsave(&cpufreq_driver_lock, flags); > list_del(&policy->policy_list); > @@ -1527,8 +1534,6 @@ static int cpufreq_online(unsigned int cpu) > for_each_cpu(j, policy->real_cpus) > remove_cpu_dev_symlink(policy, j, get_cpu_device(j)); > > - cpumask_clear(policy->cpus); > - > out_offline_policy: > if (cpufreq_driver->offline) > cpufreq_driver->offline(policy); > @@ -1538,6 +1543,7 @@ static int cpufreq_online(unsigned int cpu) > cpufreq_driver->exit(policy); > > out_free_policy: > + cpumask_clear(policy->cpus); > up_write(&policy->rwsem); > > cpufreq_policy_free(policy); > --
Applied as 5.20 material, thanks!
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