Re: [PATCH v3 1/5] PM / devfreq: Fix cpufreq passive unregister erroring on PROBE_DEFER

From: Chanwoo Choi
Date: Tue Jun 14 2022 - 18:58:32 EST


On 22. 6. 14. 20:06, Christian 'Ansuel' Marangi wrote:
> With the passive governor, the cpu based scaling can PROBE_DEFER due to
> the fact that CPU policy are not ready.
> The cpufreq passive unregister notifier is called both from the
> GOV_START errors and for the GOV_STOP and assume the notifier is
> successfully registred every time. With GOV_START failing it's wrong to
> loop over each possible CPU since the register path has failed for
> some CPU policy not ready. Change the logic and unregister the notifer
> based on the current allocated parent_cpu_data list to correctly handle
> errors and the governor unregister path.
>
> Fixes: a03dacb0316f ("PM / devfreq: Add cpu based scaling support to passive governor")
> Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@xxxxxxxxx>
> ---
> drivers/devfreq/governor_passive.c | 23 ++++++-----------------
> 1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 72c67979ebe1..0188c32f5198 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -222,8 +222,8 @@ static int cpufreq_passive_unregister_notifier(struct devfreq *devfreq)
> {
> struct devfreq_passive_data *p_data
> = (struct devfreq_passive_data *)devfreq->data;
> - struct devfreq_cpu_data *parent_cpu_data;
> - int cpu, ret = 0;
> + struct devfreq_cpu_data *parent_cpu_data, *tmp;
> + int ret;
>
> if (p_data->nb.notifier_call) {
> ret = cpufreq_unregister_notifier(&p_data->nb,
> @@ -232,27 +232,16 @@ static int cpufreq_passive_unregister_notifier(struct devfreq *devfreq)
> return ret;
> }
>
> - for_each_possible_cpu(cpu) {
> - struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> - if (!policy) {
> - ret = -EINVAL;
> - continue;
> - }
> -
> - parent_cpu_data = get_parent_cpu_data(p_data, policy);
> - if (!parent_cpu_data) {
> - cpufreq_cpu_put(policy);
> - continue;
> - }
> -
> + list_for_each_entry_safe(parent_cpu_data, tmp, &p_data->cpu_data_list, node) {
> list_del(&parent_cpu_data->node);
> +
> if (parent_cpu_data->opp_table)
> dev_pm_opp_put_opp_table(parent_cpu_data->opp_table);
> +
> kfree(parent_cpu_data);
> - cpufreq_cpu_put(policy);
> }

I agree this patch. Just, I'd like to make the separate function
to handle the removing of parent_cpu_data.

Please add new delete_parent_cpu_data() function under get_parent_cpu_data()
implementation and then call delete_parent_cpu_data()
in cpufreq_passive_unregister_notifier().

>
> - return ret;
> + return 0;
> }
>
> static int cpufreq_passive_register_notifier(struct devfreq *devfreq)


--
Best Regards,
Samsung Electronics
Chanwoo Choi