linux-kernel - Re: [PATCH 2/7] cpufreq: Init policy->rwsem before it may be possibly used

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Message-ID: <a6a20085-e1c7-4015-b0cc-d4ba4a21be30@huawei.com>
Date: Fri, 4 Jul 2025 17:04:30 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: <viresh.kumar@...aro.org>, <ionela.voinescu@....com>,
	<linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
	<linuxarm@...wei.com>, <jonathan.cameron@...wei.com>,
	<zhanjie9@...ilicon.com>, <lihuisong@...wei.com>, <yubowen8@...wei.com>
Subject: Re: [PATCH 2/7] cpufreq: Init policy->rwsem before it may be possibly
 used

On 2025/6/23 23:29, Rafael J. Wysocki wrote:

> On Mon, Jun 23, 2025 at 3:34 PM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>>
>> In cpufreq_policy_put_kobj(), policy->rwsem is used. But in
>> cpufreq_policy_alloc(), if freq_qos_add_notifier() returns an error, error
>> path via err_kobj_remove or err_min_qos_notifier will be reached and
>> cpufreq_policy_put_kobj() will be called before policy->rwsem is
>> initialized. Thus, the calling of init_rwsem() should be moved to where
>> before these two error paths can be reached.
> 
> Since this is a fix, any chance to add a Fixes: tag here?

You are right. Will add it. Thanks.

> 
>> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
>> ---
>>  drivers/cpufreq/cpufreq.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index 1bc665b5bba8..efc1f4ac85cb 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -1284,6 +1284,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
>>                 goto err_free_real_cpus;
>>         }
>>
>> +       init_rwsem(&policy->rwsem);
>> +
>>         freq_constraints_init(&policy->constraints);
>>
>>         policy->nb_min.notifier_call = cpufreq_notifier_min;
>> @@ -1306,7 +1308,6 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
>>         }
>>
>>         INIT_LIST_HEAD(&policy->policy_list);
>> -       init_rwsem(&policy->rwsem);
>>         spin_lock_init(&policy->transition_lock);
>>         init_waitqueue_head(&policy->transition_wait);
>>         INIT_WORK(&policy->update, handle_update);
>> --
>> 2.33.0
>>
>