linux-kernel - Re: [PATCH] cpufreq: Judging new_policy before update related

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Date:   Tue, 2 Feb 2021 15:11:56 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Xuewen Yan <xuewen.yan94@...il.com>
Cc:     rjw@...ysocki.net, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, xuewyan@...mail.com,
        Xuewen.Yan@...soc.com
Subject: Re: [PATCH] cpufreq: Judging new_policy before update related_cpus

On 02-02-21, 17:36, Xuewen Yan wrote:
> From: Xuewen Yan <xuewen.yan@...soc.com>
> 
> When the policy->related_cpus are all offline, and then
> bring up one cpu, this time, if the ->online is NULL,
> the code would update the ->related_cpus with ->cpus,
> and now ->cpus is only one online cpu, as a result, the
> ->related_cpus is different from the origion ->related_cpus.
> 
> Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>
> ---
>  drivers/cpufreq/cpufreq.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index d0a3525ce27f..3d512ac463a5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1374,8 +1374,10 @@ static int cpufreq_online(unsigned int cpu)
>  		if (ret)
>  			goto out_exit_policy;
>  
> -		/* related_cpus should at least include policy->cpus. */
> -		cpumask_copy(policy->related_cpus, policy->cpus);
> +		if (new_policy) {
> +			/* related_cpus should at least include policy->cpus. */
> +			cpumask_copy(policy->related_cpus, policy->cpus);
> +		}
>  	}

The driver's ->init() callback is responsible for filling policy->cpus
here.

-- 
viresh