linux-kernel - Re: [PATCH v3 2/3] cpufreq: Add a new function to get cpufreq policy without checking if the CPU is online

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Message-ID: <7586dd30-74b5-4e23-9ee2-bb82d3cb8bd4@huawei.com>
Date: Tue, 5 Aug 2025 21:32:45 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: <catalin.marinas@....com>, <will@...nel.org>, <viresh.kumar@...aro.org>,
	<beata.michalska@....com>, <sudeep.holla@....com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>,
	<jonathan.cameron@...wei.com>, <vincent.guittot@...aro.org>,
	<yangyicong@...ilicon.com>, <zhanjie9@...ilicon.com>, <lihuisong@...wei.com>,
	<yubowen8@...wei.com>, <linhongye@...artners.com>
Subject: Re: [PATCH v3 2/3] cpufreq: Add a new function to get cpufreq policy
 without checking if the CPU is online

On 2025/8/5 20:57, Rafael J. Wysocki wrote:

> On Tue, Aug 5, 2025 at 11:34 AM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>>
>> cpufreq_cpu_get_raw() gets cpufreq policy only if the CPU is in
>> policy->cpus mask, which means the CPU is already online. But in some
>> cases, the policy is needed before the CPU is added to cpus mask. Add a
>> function to get the policy in these cases.
>>
>> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
>> ---
>>  drivers/cpufreq/cpufreq.c | 11 +++++++++++
>>  include/linux/cpufreq.h   |  1 +
>>  2 files changed, 12 insertions(+)
>>
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index fc7eace8b65b..2de76a072893 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -198,6 +198,17 @@ struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
>>  }
>>  EXPORT_SYMBOL_GPL(cpufreq_cpu_get_raw);
>>
>> +struct cpufreq_policy *cpufreq_cpu_get_raw_no_check(unsigned int cpu)
> 
> This is not a particularly nice name.  Maybe call it cpufreq_cpu_policy()?

Thanks for giving a better one.

> 
>> +{
>> +       struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
>> +
>> +       if (policy)
>> +               return policy;
>> +
>> +       return NULL;
> 
> This could just be a one-liner with this statement in the function body:
> 
>   return per_cpu(cpufreq_cpu_data, cpu);
> 
> Can't it?
> 
> In which case it can be called in all places reading cpufreq_cpu_data
> for a given CPU.

Yes, it can be done in one line. Thanks.

> 
>> +}
>> +EXPORT_SYMBOL_GPL(cpufreq_cpu_get_raw_no_check);
>> +
>>  unsigned int cpufreq_generic_get(unsigned int cpu)
>>  {
>>         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
>> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
>> index 95f3807c8c55..02ad8173dc10 100644
>> --- a/include/linux/cpufreq.h
>> +++ b/include/linux/cpufreq.h
>> @@ -205,6 +205,7 @@ struct cpufreq_freqs {
>>
>>  #ifdef CONFIG_CPU_FREQ
>>  struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu);
>> +struct cpufreq_policy *cpufreq_cpu_get_raw_no_check(unsigned int cpu);
>>  struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu);
>>  void cpufreq_cpu_put(struct cpufreq_policy *policy);
>>  #else
>> --
>