RE: Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[MyungJoo Ham]

>On 2018년 04월 13일 11:37, arvindY wrote:
>> On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:
>>> On 2018년 04월 13일 11:15, arvindY wrote:
 On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
> On 2018년 04월 13일 10:03, Chanwoo Choi wrote:
[]
>>> 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(>dev);
>>>if (err) {
>>>mutex_unlock(>lock);
>>> -goto err_dev;
>>> +put_device(>dev);
>>> +goto err_out;
>>>}
>>>  devfreq->trans_table =devm_kzalloc(>dev,
>>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device 
>>> *dev,
>>>mutex_unlock(_list_lock);
>>>  device_unregister(>dev);
>>> +devfreq = NULL;
>>>err_dev:
>>>if (devfreq)
>>>kfree(devfreq);
>>>

Ah.. this was critcal. Thanks!

Acked-by: MyungJoo Ham 

>Reviewed-by: Chanwoo Choi 


Cheers,
MyungJoo

RE: Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[MyungJoo Ham]

>On 2018년 04월 13일 11:37, arvindY wrote:
>> On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:
>>> On 2018년 04월 13일 11:15, arvindY wrote:
 On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
> On 2018년 04월 13일 10:03, Chanwoo Choi wrote:
[]
>>> 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(>dev);
>>>if (err) {
>>>mutex_unlock(>lock);
>>> -goto err_dev;
>>> +put_device(>dev);
>>> +goto err_out;
>>>}
>>>  devfreq->trans_table =devm_kzalloc(>dev,
>>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device 
>>> *dev,
>>>mutex_unlock(_list_lock);
>>>  device_unregister(>dev);
>>> +devfreq = NULL;
>>>err_dev:
>>>if (devfreq)
>>>kfree(devfreq);
>>>

Ah.. this was critcal. Thanks!

Acked-by: MyungJoo Ham 

>Reviewed-by: Chanwoo Choi 


Cheers,
MyungJoo

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

On 2018년 04월 13일 11:37, arvindY wrote:
> 
> 
> On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:
>> On 2018년 04월 13일 11:15, arvindY wrote:
>>> Hi Chanwoo,
>>>
>>> On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
 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 
>> ---
>>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(>dev);
>>if (err) {
>>mutex_unlock(>lock);
>> -goto err_dev;
>> +put_device(>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.
>>> If you will see the comment for device_register(drivers/base/core.c)
>>> there is mentioned that 'NOTE: _Never_ directly free @dev
>>> after calling this function, even if it returned an error!
>>> Always use put_device() to give up the reference initialized
>>> in this function instead. Here  put_device() will decrement
>>> the last reference and then free the memory by calling dev->release.
>>> Internally put_device() -> kobject_put() -> kobject_cleanup() which
>>> is responsible to call 'dev -> release' and also free other kobject 
>>> resources.
>>>
>>> We are releasing devfreq in devfreq_dev_release(). So no need
>>> to call kfree() again. It'll be redundant.  'err_out' is correct.
>> You're right. err_out is correct.
>> put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)
>>
>>}
>>  devfreq->trans_table =devm_kzalloc(>dev,
>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device 
>> *dev,
>>mutex_unlock(_list_lock);
>>  device_unregister(>dev);
>> +devfreq = NULL;
> It is wrong. If you initialize the devfreq as NULL,
> never free the 'devfreq' instance.
>>> No need to release memory after device_unregister().
>>> driver core will take care of this. It will release memory
>>> So no need to call free again.
>> If you have to initialize the devfreq instance as NULL,
>> I think that you better to init in the devfreq_dev_release()
>> as following:
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index fe2af6aa88fc..8c52a13d3887 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
>>mutex_destroy(>lock);
>>  kfree(devfreq);
>> +   devfreq = NULL;
>>   }
> 
> Yes, You are right. I will share a update patch.
> Thanks for reviewing.

It is my mistake. 'devfreq' is local variable in the devfreq_dev_release(0.  
Even if initializes 'devfreq = NULL' in the devfreq_dev_release(),
it cannot initialize the 'devfreq' local variable in the devfreq_add_device().

I think that your original patch is good.
Reviewed-by: Chanwoo Choi 

>>
>>err_dev:
>>if (devfreq)
>>kfree(devfreq);
>>
>>> ~arvind
>>>
>>>
>>>
>>
> 
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

On 2018년 04월 13일 11:37, arvindY wrote:
> 
> 
> On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:
>> On 2018년 04월 13일 11:15, arvindY wrote:
>>> Hi Chanwoo,
>>>
>>> On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
 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 
>> ---
>>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(>dev);
>>if (err) {
>>mutex_unlock(>lock);
>> -goto err_dev;
>> +put_device(>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.
>>> If you will see the comment for device_register(drivers/base/core.c)
>>> there is mentioned that 'NOTE: _Never_ directly free @dev
>>> after calling this function, even if it returned an error!
>>> Always use put_device() to give up the reference initialized
>>> in this function instead. Here  put_device() will decrement
>>> the last reference and then free the memory by calling dev->release.
>>> Internally put_device() -> kobject_put() -> kobject_cleanup() which
>>> is responsible to call 'dev -> release' and also free other kobject 
>>> resources.
>>>
>>> We are releasing devfreq in devfreq_dev_release(). So no need
>>> to call kfree() again. It'll be redundant.  'err_out' is correct.
>> You're right. err_out is correct.
>> put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)
>>
>>}
>>  devfreq->trans_table =devm_kzalloc(>dev,
>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device 
>> *dev,
>>mutex_unlock(_list_lock);
>>  device_unregister(>dev);
>> +devfreq = NULL;
> It is wrong. If you initialize the devfreq as NULL,
> never free the 'devfreq' instance.
>>> No need to release memory after device_unregister().
>>> driver core will take care of this. It will release memory
>>> So no need to call free again.
>> If you have to initialize the devfreq instance as NULL,
>> I think that you better to init in the devfreq_dev_release()
>> as following:
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index fe2af6aa88fc..8c52a13d3887 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
>>mutex_destroy(>lock);
>>  kfree(devfreq);
>> +   devfreq = NULL;
>>   }
> 
> Yes, You are right. I will share a update patch.
> Thanks for reviewing.

It is my mistake. 'devfreq' is local variable in the devfreq_dev_release(0.  
Even if initializes 'devfreq = NULL' in the devfreq_dev_release(),
it cannot initialize the 'devfreq' local variable in the devfreq_add_device().

I think that your original patch is good.
Reviewed-by: Chanwoo Choi 

>>
>>err_dev:
>>if (devfreq)
>>kfree(devfreq);
>>
>>> ~arvind
>>>
>>>
>>>
>>
> 
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[arvindY]

On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:

On 2018년 04월 13일 11:15, arvindY wrote:

Hi Chanwoo,

On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:

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 
---
   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(>dev);
   if (err) {
   mutex_unlock(>lock);
-goto err_dev;
+put_device(>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.

If you will see the comment for device_register(drivers/base/core.c)
there is mentioned that 'NOTE: _Never_ directly free @dev
after calling this function, even if it returned an error!
Always use put_device() to give up the reference initialized
in this function instead. Here  put_device() will decrement
the last reference and then free the memory by calling dev->release.
Internally put_device() -> kobject_put() -> kobject_cleanup() which
is responsible to call 'dev -> release' and also free other kobject resources.

We are releasing devfreq in devfreq_dev_release(). So no need
to call kfree() again. It'll be redundant.  'err_out' is correct.

You're right. err_out is correct.
put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)


   }
 devfreq->trans_table =devm_kzalloc(>dev,
@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
   mutex_unlock(_list_lock);
 device_unregister(>dev);
+devfreq = NULL;

It is wrong. If you initialize the devfreq as NULL,
never free the 'devfreq' instance.

No need to release memory after device_unregister().
driver core will take care of this. It will release memory
So no need to call free again.

If you have to initialize the devfreq instance as NULL,
I think that you better to init in the devfreq_dev_release()
as following:

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index fe2af6aa88fc..8c52a13d3887 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
  
 mutex_destroy(>lock);

 kfree(devfreq);
+   devfreq = NULL;
  }


Yes, You are right. I will share a update patch.
Thanks for reviewing.



   err_dev:
   if (devfreq)
   kfree(devfreq);


~arvind

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[arvindY]

On Friday 13 April 2018 07:59 AM, Chanwoo Choi wrote:

On 2018년 04월 13일 11:15, arvindY wrote:

Hi Chanwoo,

On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:

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 
---
   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(>dev);
   if (err) {
   mutex_unlock(>lock);
-goto err_dev;
+put_device(>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.

If you will see the comment for device_register(drivers/base/core.c)
there is mentioned that 'NOTE: _Never_ directly free @dev
after calling this function, even if it returned an error!
Always use put_device() to give up the reference initialized
in this function instead. Here  put_device() will decrement
the last reference and then free the memory by calling dev->release.
Internally put_device() -> kobject_put() -> kobject_cleanup() which
is responsible to call 'dev -> release' and also free other kobject resources.

We are releasing devfreq in devfreq_dev_release(). So no need
to call kfree() again. It'll be redundant.  'err_out' is correct.

You're right. err_out is correct.
put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)


   }
 devfreq->trans_table =devm_kzalloc(>dev,
@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
   mutex_unlock(_list_lock);
 device_unregister(>dev);
+devfreq = NULL;

It is wrong. If you initialize the devfreq as NULL,
never free the 'devfreq' instance.

No need to release memory after device_unregister().
driver core will take care of this. It will release memory
So no need to call free again.

If you have to initialize the devfreq instance as NULL,
I think that you better to init in the devfreq_dev_release()
as following:

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index fe2af6aa88fc..8c52a13d3887 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
  
 mutex_destroy(>lock);

 kfree(devfreq);
+   devfreq = NULL;
  }


Yes, You are right. I will share a update patch.
Thanks for reviewing.



   err_dev:
   if (devfreq)
   kfree(devfreq);


~arvind

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

On 2018년 04월 13일 11:15, arvindY wrote:
> Hi Chanwoo,
> 
> On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
>> 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 
 ---
   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(>dev);
   if (err) {
   mutex_unlock(>lock);
 -goto err_dev;
 +put_device(>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.
> 
> If you will see the comment for device_register(drivers/base/core.c)
> there is mentioned that 'NOTE: _Never_ directly free @dev
> after calling this function, even if it returned an error!
> Always use put_device() to give up the reference initialized
> in this function instead. Here  put_device() will decrement
> the last reference and then free the memory by calling dev->release.
> Internally put_device() -> kobject_put() -> kobject_cleanup() which
> is responsible to call 'dev -> release' and also free other kobject resources.
> 
> We are releasing devfreq in devfreq_dev_release(). So no need
> to call kfree() again. It'll be redundant.  'err_out' is correct.

You're right. err_out is correct.
put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)

>>
   }
 devfreq->trans_table =devm_kzalloc(>dev,
 @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
   mutex_unlock(_list_lock);
 device_unregister(>dev);
 +devfreq = NULL;
>>> It is wrong. If you initialize the devfreq as NULL,
>>> never free the 'devfreq' instance.
> 
> No need to release memory after device_unregister().
> driver core will take care of this. It will release memory
> So no need to call free again.

If you have to initialize the devfreq instance as NULL,
I think that you better to init in the devfreq_dev_release()
as following:

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index fe2af6aa88fc..8c52a13d3887 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
 
mutex_destroy(>lock);
kfree(devfreq);
+   devfreq = NULL;
 }


>>>
   err_dev:
   if (devfreq)
   kfree(devfreq);

>>>
>>
> 
> ~arvind
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

On 2018년 04월 13일 11:15, arvindY wrote:
> Hi Chanwoo,
> 
> On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:
>> 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 
 ---
   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(>dev);
   if (err) {
   mutex_unlock(>lock);
 -goto err_dev;
 +put_device(>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.
> 
> If you will see the comment for device_register(drivers/base/core.c)
> there is mentioned that 'NOTE: _Never_ directly free @dev
> after calling this function, even if it returned an error!
> Always use put_device() to give up the reference initialized
> in this function instead. Here  put_device() will decrement
> the last reference and then free the memory by calling dev->release.
> Internally put_device() -> kobject_put() -> kobject_cleanup() which
> is responsible to call 'dev -> release' and also free other kobject resources.
> 
> We are releasing devfreq in devfreq_dev_release(). So no need
> to call kfree() again. It'll be redundant.  'err_out' is correct.

You're right. err_out is correct.
put_device() -> dev->release() -> devfreq_dev_release() -> kfree(devfreq)

>>
   }
 devfreq->trans_table =devm_kzalloc(>dev,
 @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
   mutex_unlock(_list_lock);
 device_unregister(>dev);
 +devfreq = NULL;
>>> It is wrong. If you initialize the devfreq as NULL,
>>> never free the 'devfreq' instance.
> 
> No need to release memory after device_unregister().
> driver core will take care of this. It will release memory
> So no need to call free again.

If you have to initialize the devfreq instance as NULL,
I think that you better to init in the devfreq_dev_release()
as following:

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index fe2af6aa88fc..8c52a13d3887 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -543,6 +543,7 @@ static void devfreq_dev_release(struct device *dev)
 
mutex_destroy(>lock);
kfree(devfreq);
+   devfreq = NULL;
 }


>>>
   err_dev:
   if (devfreq)
   kfree(devfreq);

>>>
>>
> 
> ~arvind
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[arvindY]

Hi Chanwoo,

On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:

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 
---
  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(>dev);
if (err) {
mutex_unlock(>lock);
-   goto err_dev;
+   put_device(>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.


If you will see the comment for device_register(drivers/base/core.c)
there is mentioned that 'NOTE: _Never_ directly free @dev
after calling this function, even if it returned an error!
Always use put_device() to give up the reference initialized
in this function instead. Here  put_device() will decrement
the last reference and then free the memory by calling dev->release.
Internally put_device() -> kobject_put() -> kobject_cleanup() which
is responsible to call 'dev -> release' and also free other kobject 
resources.


We are releasing devfreq in devfreq_dev_release(). So no need
to call kfree() again. It'll be redundant.  'err_out' is correct.



}
  
  	devfreq->trans_table =	devm_kzalloc(>dev,

@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
mutex_unlock(_list_lock);
  
  	device_unregister(>dev);

+   devfreq = NULL;

It is wrong. If you initialize the devfreq as NULL,
never free the 'devfreq' instance.


No need to release memory after device_unregister().
driver core will take care of this. It will release memory
So no need to call free again.



  err_dev:
if (devfreq)
kfree(devfreq);







~arvind

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[arvindY]

Hi Chanwoo,

On Friday 13 April 2018 06:43 AM, Chanwoo Choi wrote:

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 
---
  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(>dev);
if (err) {
mutex_unlock(>lock);
-   goto err_dev;
+   put_device(>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.


If you will see the comment for device_register(drivers/base/core.c)
there is mentioned that 'NOTE: _Never_ directly free @dev
after calling this function, even if it returned an error!
Always use put_device() to give up the reference initialized
in this function instead. Here  put_device() will decrement
the last reference and then free the memory by calling dev->release.
Internally put_device() -> kobject_put() -> kobject_cleanup() which
is responsible to call 'dev -> release' and also free other kobject 
resources.


We are releasing devfreq in devfreq_dev_release(). So no need
to call kfree() again. It'll be redundant.  'err_out' is correct.



}
  
  	devfreq->trans_table =	devm_kzalloc(>dev,

@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
mutex_unlock(_list_lock);
  
  	device_unregister(>dev);

+   devfreq = NULL;

It is wrong. If you initialize the devfreq as NULL,
never free the 'devfreq' instance.


No need to release memory after device_unregister().
driver core will take care of this. It will release memory
So no need to call free again.



  err_dev:
if (devfreq)
kfree(devfreq);







~arvind

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

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 
>> ---
>>  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(>dev);
>>  if (err) {
>>  mutex_unlock(>lock);
>> -goto err_dev;
>> +put_device(>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(>dev,
>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  mutex_unlock(_list_lock);
>>  
>>  device_unregister(>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

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

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 
>> ---
>>  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(>dev);
>>  if (err) {
>>  mutex_unlock(>lock);
>> -goto err_dev;
>> +put_device(>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(>dev,
>> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  mutex_unlock(_list_lock);
>>  
>>  device_unregister(>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

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

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 
> ---
>  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(>dev);
>   if (err) {
>   mutex_unlock(>lock);
> - goto err_dev;
> + put_device(>dev);
> + goto err_out;

why do you change the goto postion?
err_out is correct to free the memory of devfreq instance.

>   }
>  
>   devfreq->trans_table =  devm_kzalloc(>dev,
> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>   mutex_unlock(_list_lock);
>  
>   device_unregister(>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

Re: [PATCH] PM / devfreq: use put_device() instead of kfree()

[Chanwoo Choi]

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 
> ---
>  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(>dev);
>   if (err) {
>   mutex_unlock(>lock);
> - goto err_dev;
> + put_device(>dev);
> + goto err_out;

why do you change the goto postion?
err_out is correct to free the memory of devfreq instance.

>   }
>  
>   devfreq->trans_table =  devm_kzalloc(>dev,
> @@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>   mutex_unlock(_list_lock);
>  
>   device_unregister(>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

[PATCH] PM / devfreq: use put_device() instead of kfree()

[Arvind Yadav]

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 
---
 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(>dev);
if (err) {
mutex_unlock(>lock);
-   goto err_dev;
+   put_device(>dev);
+   goto err_out;
}
 
devfreq->trans_table =  devm_kzalloc(>dev,
@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
mutex_unlock(_list_lock);
 
device_unregister(>dev);
+   devfreq = NULL;
 err_dev:
if (devfreq)
kfree(devfreq);
-- 
2.7.4

[PATCH] PM / devfreq: use put_device() instead of kfree()

[Arvind Yadav]

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 
---
 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(>dev);
if (err) {
mutex_unlock(>lock);
-   goto err_dev;
+   put_device(>dev);
+   goto err_out;
}
 
devfreq->trans_table =  devm_kzalloc(>dev,
@@ -671,6 +672,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
mutex_unlock(_list_lock);
 
device_unregister(>dev);
+   devfreq = NULL;
 err_dev:
if (devfreq)
kfree(devfreq);
-- 
2.7.4