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Date:   Fri, 28 Jun 2019 11:12:56 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Eduardo Valentin <edubezval@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Keerthy <j-keerthy@...com>,
        "open list:CPU FREQUENCY DRIVERS - ARM BIG LITTLE" 
        <linux-pm@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:TI BANDGAP AND THERMAL DRIVER" 
        <linux-omap@...r.kernel.org>
Subject: Re: [PATCH V4 2/3] thermal/drivers/cpu_cooling: Unregister with the policy

On Thu, Jun 27, 2019 at 11:02 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> Currently the function cpufreq_cooling_register() returns a cooling
> device pointer which is used back as a pointer to call the function
> cpufreq_cooling_unregister(). Even if it is correct, it would make
> sense to not leak the structure inside a cpufreq driver and keep the
> code thermal code self-encapsulate. Moreover, that forces to add an
> extra variable in each driver using this function.
>
> Instead of passing the cooling device to unregister, pass the policy.
>
> Because the cpufreq_cooling_unregister() function uses the policy to
> unregister itself. The only purpose of the cooling device pointer is
> to unregister the cpu cooling device.
>
> As there is no more need of this pointer, remove it.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

This doesn't apply for me.

Care to rebase it on top of the Linus' tree?

Also see below.

> ---
>  drivers/cpufreq/arm_big_little.c              |  9 ++--
>  drivers/cpufreq/cpufreq.c                     |  8 ++--
>  drivers/thermal/cpu_cooling.c                 | 42 +++++++++++--------
>  drivers/thermal/imx_thermal.c                 | 12 +++---
>  .../ti-soc-thermal/ti-thermal-common.c        | 10 ++---
>  include/linux/cpu_cooling.h                   |  6 +--
>  include/linux/cpufreq.h                       |  3 --
>  7 files changed, 45 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
> index 7fe52fcddcf1..718c63231e66 100644
> --- a/drivers/cpufreq/arm_big_little.c
> +++ b/drivers/cpufreq/arm_big_little.c
> @@ -56,7 +56,6 @@ static bool bL_switching_enabled;
>  #define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
>  #define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)
>
> -static struct thermal_cooling_device *cdev[MAX_CLUSTERS];
>  static const struct cpufreq_arm_bL_ops *arm_bL_ops;
>  static struct clk *clk[MAX_CLUSTERS];
>  static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
> @@ -501,10 +500,8 @@ static int bL_cpufreq_exit(struct cpufreq_policy *policy)
>         struct device *cpu_dev;
>         int cur_cluster = cpu_to_cluster(policy->cpu);
>
> -       if (cur_cluster < MAX_CLUSTERS) {
> -               cpufreq_cooling_unregister(cdev[cur_cluster]);
> -               cdev[cur_cluster] = NULL;
> -       }
> +       if (cur_cluster < MAX_CLUSTERS)
> +               cpufreq_cooling_unregister(policy);
>
>         cpu_dev = get_cpu_device(policy->cpu);
>         if (!cpu_dev) {
> @@ -527,7 +524,7 @@ static void bL_cpufreq_ready(struct cpufreq_policy *policy)
>         if (cur_cluster >= MAX_CLUSTERS)
>                 return;
>
> -       cdev[cur_cluster] = of_cpufreq_cooling_register(policy);
> +       of_cpufreq_cooling_register(policy);
>  }
>
>  static struct cpufreq_driver bL_cpufreq_driver = {
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index aee024e42618..1663a5601811 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1379,7 +1379,7 @@ static int cpufreq_online(unsigned int cpu)
>                 cpufreq_driver->ready(policy);
>
>         if (cpufreq_thermal_control_enabled(cpufreq_driver))
> -               policy->cdev = of_cpufreq_cooling_register(policy);
> +               of_cpufreq_cooling_register(policy);
>
>         pr_debug("initialization complete\n");
>
> @@ -1468,10 +1468,8 @@ static int cpufreq_offline(unsigned int cpu)
>                 goto unlock;
>         }
>
> -       if (cpufreq_thermal_control_enabled(cpufreq_driver)) {
> -               cpufreq_cooling_unregister(policy->cdev);
> -               policy->cdev = NULL;
> -       }
> +       if (cpufreq_thermal_control_enabled(cpufreq_driver))
> +               cpufreq_cooling_unregister(policy);
>
>         if (cpufreq_driver->stop_cpu)
>                 cpufreq_driver->stop_cpu(policy);
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 83486775e593..be01546a656f 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -78,6 +78,7 @@ struct cpufreq_cooling_device {
>         struct cpufreq_policy *policy;
>         struct list_head node;
>         struct time_in_idle *idle_time;
> +       struct thermal_cooling_device *cdev;
>  };
>
>  static DEFINE_IDA(cpufreq_ida);
> @@ -606,6 +607,7 @@ __cpufreq_cooling_register(struct device_node *np,
>                 goto remove_ida;
>
>         cpufreq_cdev->clipped_freq = get_state_freq(cpufreq_cdev, 0);
> +       cpufreq_cdev->cdev = cdev;
>
>         mutex_lock(&cooling_list_lock);
>         /* Register the notifier for first cpufreq cooling device */
> @@ -693,35 +695,41 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy)
>  }
>  EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
>
> +void __cpufreq_cooling_unregister(struct cpufreq_cooling_device *cpufreq_cdev, int last)
> +{
> +       /* Unregister the notifier for the last cpufreq cooling device */
> +       if (last)
> +               cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> +                                           CPUFREQ_POLICY_NOTIFIER);
> +
> +       thermal_cooling_device_unregister(cpufreq_cdev->cdev);
> +       ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
> +       kfree(cpufreq_cdev->idle_time);
> +       kfree(cpufreq_cdev);
> +}
> +
>  /**
>   * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>   * @cdev: thermal cooling device pointer.
>   *
>   * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
>   */
> -void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +void cpufreq_cooling_unregister(struct cpufreq_policy *policy)
>  {
>         struct cpufreq_cooling_device *cpufreq_cdev;

I would do

        struct cpufreq_cooling_device *ccd, *cpufreq_cdev = NULL;

and then ->

>         bool last;
>
> -       if (!cdev)
> -               return;
> -
> -       cpufreq_cdev = cdev->devdata;
> -
>         mutex_lock(&cooling_list_lock);
> -       list_del(&cpufreq_cdev->node);
> -       /* Unregister the notifier for the last cpufreq cooling device */
> -       last = list_empty(&cpufreq_cdev_list);
> +       list_for_each_entry(cpufreq_cdev, &cpufreq_cdev_list, node) {

-> list_for_each_entry(ccd, &cpufreq_cdev_list, node) {
                if (ccd->policy == policy) {

> +               if (cpufreq_cdev->policy == policy) {

                           cpufreq_cdev = ccd;

> +                       list_del(&cpufreq_cdev->node);
> +                       last = list_empty(&cpufreq_cdev_list);
> +                       break;
> +               }
> +       }
>         mutex_unlock(&cooling_list_lock);

And here

if (!cpufreq_cdev)
        return;

And that's it.  No new functions needed.

> -       if (last)
> -               cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> -                                           CPUFREQ_POLICY_NOTIFIER);
> -

And I don't that the above needs to be changed at all in any case.


> -       thermal_cooling_device_unregister(cdev);
> -       ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
> -       kfree(cpufreq_cdev->idle_time);
> -       kfree(cpufreq_cdev);
> +       if (cpufreq_cdev->policy == policy)
> +               __cpufreq_cooling_unregister(cpufreq_cdev, last);
>  }
>  EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);
> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> index bb6754a5342c..021c0948b740 100644
> --- a/drivers/thermal/imx_thermal.c
> +++ b/drivers/thermal/imx_thermal.c
> @@ -203,7 +203,6 @@ static struct thermal_soc_data thermal_imx7d_data = {
>  struct imx_thermal_data {
>         struct cpufreq_policy *policy;
>         struct thermal_zone_device *tz;
> -       struct thermal_cooling_device *cdev;
>         enum thermal_device_mode mode;
>         struct regmap *tempmon;
>         u32 c1, c2; /* See formula in imx_init_calib() */
> @@ -656,6 +655,7 @@ MODULE_DEVICE_TABLE(of, of_imx_thermal_match);
>  static int imx_thermal_register_legacy_cooling(struct imx_thermal_data *data)
>  {
>         struct device_node *np;
> +       struct thermal_cooling_device *cdev;
>         int ret;
>
>         data->policy = cpufreq_cpu_get(0);
> @@ -667,9 +667,9 @@ static int imx_thermal_register_legacy_cooling(struct imx_thermal_data *data)
>         np = of_get_cpu_node(data->policy->cpu, NULL);
>
>         if (!np || !of_find_property(np, "#cooling-cells", NULL)) {
> -               data->cdev = cpufreq_cooling_register(data->policy);
> -               if (IS_ERR(data->cdev)) {
> -                       ret = PTR_ERR(data->cdev);
> +               cdev = cpufreq_cooling_register(data->policy);
> +               if (IS_ERR(cdev)) {
> +                       ret = PTR_ERR(cdev);
>                         cpufreq_cpu_put(data->policy);
>                         return ret;
>                 }
> @@ -680,7 +680,7 @@ static int imx_thermal_register_legacy_cooling(struct imx_thermal_data *data)
>
>  static void imx_thermal_unregister_legacy_cooling(struct imx_thermal_data *data)
>  {
> -       cpufreq_cooling_unregister(data->cdev);
> +       cpufreq_cooling_unregister(data->policy);
>         cpufreq_cpu_put(data->policy);
>  }
>
> @@ -872,7 +872,7 @@ static int imx_thermal_remove(struct platform_device *pdev)
>                 clk_disable_unprepare(data->thermal_clk);
>
>         thermal_zone_device_unregister(data->tz);
> -       cpufreq_cooling_unregister(data->cdev);
> +       cpufreq_cooling_unregister(data->policy);
>         cpufreq_cpu_put(data->policy);
>
>         return 0;
> diff --git a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> index b4f981daeaf2..170b70b6ec61 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> @@ -41,7 +41,6 @@ struct ti_thermal_data {
>         struct cpufreq_policy *policy;
>         struct thermal_zone_device *ti_thermal;
>         struct thermal_zone_device *pcb_tz;
> -       struct thermal_cooling_device *cool_dev;
>         struct ti_bandgap *bgp;
>         enum thermal_device_mode mode;
>         struct work_struct thermal_wq;
> @@ -233,6 +232,7 @@ int ti_thermal_register_cpu_cooling(struct ti_bandgap *bgp, int id)
>  {
>         struct ti_thermal_data *data;
>         struct device_node *np = bgp->dev->of_node;
> +       struct thermal_cooling_device *cdev;
>
>         /*
>          * We are assuming here that if one deploys the zone
> @@ -256,9 +256,9 @@ int ti_thermal_register_cpu_cooling(struct ti_bandgap *bgp, int id)
>         }
>
>         /* Register cooling device */
> -       data->cool_dev = cpufreq_cooling_register(data->policy);
> -       if (IS_ERR(data->cool_dev)) {
> -               int ret = PTR_ERR(data->cool_dev);
> +       cdev = cpufreq_cooling_register(data->policy);
> +       if (IS_ERR(cdev)) {
> +               int ret = PTR_ERR(cdev);
>                 dev_err(bgp->dev, "Failed to register cpu cooling device %d\n",
>                         ret);
>                 cpufreq_cpu_put(data->policy);
> @@ -277,7 +277,7 @@ int ti_thermal_unregister_cpu_cooling(struct ti_bandgap *bgp, int id)
>         data = ti_bandgap_get_sensor_data(bgp, id);
>
>         if (data) {
> -               cpufreq_cooling_unregister(data->cool_dev);
> +               cpufreq_cooling_unregister(data->policy);
>                 if (data->policy)
>                         cpufreq_cpu_put(data->policy);
>         }
> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> index bae54bb7c048..89f469ee4be4 100644
> --- a/include/linux/cpu_cooling.h
> +++ b/include/linux/cpu_cooling.h
> @@ -29,9 +29,9 @@ cpufreq_cooling_register(struct cpufreq_policy *policy);
>
>  /**
>   * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> - * @cdev: thermal cooling device pointer.
> + * @policy: cpufreq policy
>   */
> -void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
> +void cpufreq_cooling_unregister(struct cpufreq_policy *policy);
>
>  #else /* !CONFIG_CPU_THERMAL */
>  static inline struct thermal_cooling_device *
> @@ -41,7 +41,7 @@ cpufreq_cooling_register(struct cpufreq_policy *policy)
>  }
>
>  static inline
> -void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +void cpufreq_cooling_unregister(struct cpufreq_policy *policy)
>  {
>         return;
>  }
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index a1467aa7f58b..ce13204df972 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -144,9 +144,6 @@ struct cpufreq_policy {
>
>         /* For cpufreq driver's internal use */
>         void                    *driver_data;
> -
> -       /* Pointer to the cooling device if used for thermal mitigation */
> -       struct thermal_cooling_device *cdev;
>  };
>
>  struct cpufreq_freqs {
> --
> 2.17.1
>

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