Re: [PATCH v5 6/6] PM: EM: Use scope-based cleanup helper

["Rafael J. Wysocki" <rafael@kernel.org>]

On Fri, Sep 5, 2025 at 3:25 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>
> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
> annotation for policy references. This reduces the risk of reference
> counting mistakes and aligns the code with the latest kernel style.
>
> No functional change intended.
>
> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
> ---
>  kernel/power/energy_model.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index ea7995a25780..5ec63b3e7d85 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -451,7 +451,6 @@ static void
>  em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
>  {
>         struct em_perf_domain *pd = dev->em_pd;
> -       struct cpufreq_policy *policy;
>         int found = 0;
>         int i, cpu;
>
> @@ -465,7 +464,7 @@ em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
>                 return;
>         }
>
> -       policy = cpufreq_cpu_get(cpu);
> +       struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
>         if (!policy) {
>                 dev_warn(dev, "EM: Access to CPUFreq policy failed\n");
>                 return;
> @@ -479,8 +478,6 @@ em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
>                         found++;
>         }
>
> -       cpufreq_cpu_put(policy);
> -
>         if (!found)
>                 return;
>

The above changes are fine now and can be a separate patch.

> @@ -787,21 +784,19 @@ static void em_check_capacity_update(void)
>
>         /* Check if CPUs capacity has changed than update EM */
>         for_each_possible_cpu(cpu) {

But I'd prefer the code in this loop to be moved into a separate
function, in a separate patch, before the __free()-based
simplification of it.

> -               struct cpufreq_policy *policy;
>                 struct em_perf_domain *pd;
>                 struct device *dev;
>
>                 if (cpumask_test_cpu(cpu, cpu_done_mask))
>                         continue;
>
> -               policy = cpufreq_cpu_get(cpu);
> +               struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
>                 if (!policy) {
>                         pr_debug("Accessing cpu%d policy failed\n", cpu);
>                         schedule_delayed_work(&em_update_work,
>                                               msecs_to_jiffies(1000));
>                         break;
>                 }
> -               cpufreq_cpu_put(policy);
>
>                 dev = get_cpu_device(cpu);
>                 pd = em_pd_get(dev);
> --