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SubjectRe: [PATCH V2 07/11] cpufreq: Use cpufreq_policy_list for iterating over policies
Date
On Tuesday, August 06, 2013 10:53:09 PM Viresh Kumar wrote:
> For iterating over all policies currently we are iterating over all CPUs and
> then finding their policies. Lets use the newly created infrastructure
> cpufreq_policy_list.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

I noticed that the current linux-next branch of linux-pm.git caused the
BUG_ON() in lock_policy_rwsem_##mode() to trigger when user space tried to
access cpufreq sysfs attributes before system suspend and after system
resume.

I tried to debug that and it turned out that this patch caused resume
to block indefinitely on one of my test machines and after reverting it the
BUG_ON() stopped triggering, so I've just reverted it in my tree (it is not an
important change).

I don't have the time to figure out why this change breaks things and I would
appreciate it if you tested stuff like suspend/resume on an x86 laptop or
similar with your patches applied before posting them for merging.

Thanks,
Rafael


> ---
> drivers/cpufreq/cpufreq.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index f5999c4..fe04b79 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -984,8 +984,8 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
> struct cpufreq_policy *policy;
> unsigned long flags;
> #ifdef CONFIG_HOTPLUG_CPU
> + struct cpufreq_policy *tpolicy;
> struct cpufreq_governor *gov;
> - int sibling;
> #endif
>
> if (cpu_is_offline(cpu))
> @@ -1005,11 +1005,11 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
> #ifdef CONFIG_HOTPLUG_CPU
> /* Check if this cpu was hot-unplugged earlier and has siblings */
> read_lock_irqsave(&cpufreq_driver_lock, flags);
> - for_each_online_cpu(sibling) {
> - struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
> - if (cp && cpumask_test_cpu(cpu, cp->related_cpus)) {
> + list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) {
> + if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) {
> read_unlock_irqrestore(&cpufreq_driver_lock, flags);
> - return cpufreq_add_policy_cpu(cp, cpu, dev, frozen);
> + return cpufreq_add_policy_cpu(tpolicy, cpu, dev,
> + frozen);
> }
> }
> read_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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