linux-kernel - Re: [PATCH] powercap: DTPM: Fix the missing cpufreq_cpu

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Message-ID: <CAJZ5v0gYfvJCQ6Tk2Jh8ZYtaJM=sq3Qb6dq28rjYjMNPfJBT_Q@mail.gmail.com>
Date:   Tue, 5 Dec 2023 20:54:38 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        daniel.lezcano@...aro.org, rafael@...nel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] powercap: DTPM: Fix the missing cpufreq_cpu_put() calls

On Fri, Dec 1, 2023 at 1:31 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> The policy returned by cpufreq_cpu_get() has to be released with
> the help of cpufreq_cpu_put() to balance its kobject reference counter
> properly.
>
> Add the missing calls to cpufreq_cpu_put() in the code.
>
> Fixes: 0aea2e4ec2a2 ("powercap/dtpm_cpu: Reset per_cpu variable in the release function")
> Fixes: 0e8f68d7f048 ("powercap/drivers/dtpm: Add CPU energy model based support")
> Cc: <stable@...r.kernel.org> # v5.10+
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>  drivers/powercap/dtpm_cpu.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> index 45bb7e2849d7..aac278e162d9 100644
> --- a/drivers/powercap/dtpm_cpu.c
> +++ b/drivers/powercap/dtpm_cpu.c
> @@ -152,6 +152,8 @@ static void pd_release(struct dtpm *dtpm)
>         if (policy) {
>                 for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
>                         per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
> +
> +               cpufreq_cpu_put(policy);
>         }
>
>         kfree(dtpm_cpu);
> @@ -204,12 +206,16 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>                 return 0;
>
>         pd = em_cpu_get(cpu);
> -       if (!pd || em_is_artificial(pd))
> -               return -EINVAL;
> +       if (!pd || em_is_artificial(pd)) {
> +               ret = -EINVAL;
> +               goto release_policy;
> +       }
>
>         dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
> -       if (!dtpm_cpu)
> -               return -ENOMEM;
> +       if (!dtpm_cpu) {
> +               ret = -ENOMEM;
> +               goto release_policy;
> +       }
>
>         dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
>         dtpm_cpu->cpu = cpu;
> @@ -231,6 +237,7 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>         if (ret)
>                 goto out_dtpm_unregister;
>
> +       cpufreq_cpu_put(policy);
>         return 0;
>
>  out_dtpm_unregister:
> @@ -242,6 +249,8 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>                 per_cpu(dtpm_per_cpu, cpu) = NULL;
>         kfree(dtpm_cpu);
>
> +release_policy:
> +       cpufreq_cpu_put(policy);
>         return ret;
>  }
>
> --

Applied as 6.7-rc material with the Cc: stable tag fixed.

Thanks!