linux-kernel - Re: [PATCH v1] cpufreq: Avoid creating sysfs link for offline CPUs

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Message-ID: <CAJZ5v0iyAWdh=_2jcc7P5umR4T4yoatiK8cE+yT2vTiY87mxxw@mail.gmail.com>
Date: Mon, 21 Jul 2025 17:51:59 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Zihuan Zhang <zzhwaxy.kernel@...il.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] cpufreq: Avoid creating sysfs link for offline CPUs

On Mon, Jul 21, 2025 at 5:37 PM Zihuan Zhang <zzhwaxy.kernel@...il.com> wrote:
>
> Currently, cpufreq_add_dev() attempts to create a sysfs link
> even when the target CPU is offline. Although guarded by a NULL
> check on cpufreq_policy, this behavior is not strictly correct,
> since offline CPUs shouldn't have their sysfs interface created.

Why?

> This patch cleans up the logic to only add the sysfs link
> when the CPU is online and cpufreq policy is properly initialized.

I don't really think that this change is necessary.  Thanks!

> Signed-off-by: Zihuan Zhang <zzhwaxy.kernel@...il.com>
> ---
>  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 d7426e1d8bdd..0a77892d366c 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1660,12 +1660,12 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
>                 ret = cpufreq_online(cpu);
>                 if (ret)
>                         return ret;
> -       }
>
> -       /* Create sysfs link on CPU registration */
> -       policy = per_cpu(cpufreq_cpu_data, cpu);
> -       if (policy)
> -               add_cpu_dev_symlink(policy, cpu, dev);
> +               /* Create sysfs link on CPU registration */
> +               policy = per_cpu(cpufreq_cpu_data, cpu);
> +               if (policy)
> +                       add_cpu_dev_symlink(policy, cpu, dev);
> +       }
>
>         return 0;
>  }
> --