linux-kernel - Re: [PATCH] PM / devfreq: use put

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Message-id: <5AD0041D.2050506@samsung.com>
Date:   Fri, 13 Apr 2018 10:13:01 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

On 2018년 04월 13일 10:03, Chanwoo Choi wrote:
> Hi,
> 
> I'm sorry for the late reply.
> 
> On 2018년 03월 30일 20:44, Arvind Yadav wrote:
>> Never directly free @dev after calling device_register() or
>> device_unregister(), even if device_register() returned an error.
>> Always use put_device() to give up the reference initialized.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>>  drivers/devfreq/devfreq.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index fe2af6a..a225b94 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -625,7 +625,8 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  	err = device_register(&devfreq->dev);
>>  	if (err) {
>>  		mutex_unlock(&devfreq->lock);
>> -		goto err_dev;
>> +		put_device(&devfreq->dev);
>> +		goto err_out;
> 
> why do you change the goto postion?
> err_out is correct to free the memory of devfreq instance.

Sorry. err_dev is correct instead of err_out.

> 
>>  	}
>>  
>>  	devfreq->trans_table =	devm_kzalloc(&devfreq->dev,
>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  	mutex_unlock(&devfreq_list_lock);
>>  
>>  	device_unregister(&devfreq->dev);
>> +	devfreq = NULL;
> 
> It is wrong. If you initialize the devfreq as NULL,
> never free the 'devfreq' instance.
> 
>>  err_dev:
>>  	if (devfreq)
>>  		kfree(devfreq);
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics