Subject: [PATCH RFT 1/5] iio: mxs-lradc: fix memory leak

From: [email-masked] (Stefan Wahren)
Date: Tue, 19 Apr 2016 15:37:19 +0200

Hi Marek,

Am 19.04.2016 um 12:32 schrieb Marek Vasut:
> On 04/19/2016 08:33 AM, Stefan Wahren wrote:
>> Hi Marek,
>>
>> Am 18.04.2016 um 19:16 schrieb Marek Vasut:
>>> On 04/17/2016 12:08 PM, Jonathan Cameron wrote:
>>>> On 14/04/16 21:01, Marek Vasut wrote:
>>>>> On 04/14/2016 05:48 PM, Stefan Wahren wrote:
>>>>>> After successful touchscreen registration the input device was
>>>>>> never freed. So fix this issue by using devm_input_allocate_device().
>>>>>>
>>>>>> Signed-off-by: Stefan Wahren <[email-masked]>
>>>>>> ---
>>>>>>  drivers/iio/adc/mxs-lradc.c |    8 ++------
>>>>>>  1 file changed, 2 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/iio/adc/mxs-lradc.c b/drivers/iio/adc/mxs-lradc.c
>>>>>> index 33051b8..0576953 100644
>>>>>> --- a/drivers/iio/adc/mxs-lradc.c
>>>>>> +++ b/drivers/iio/adc/mxs-lradc.c
>>>>>> @@ -1109,12 +1109,11 @@ static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
>>>>>>  {
>>>>>>  	struct input_dev *input;
>>>>>>  	struct device *dev = lradc->dev;
>>>>>> -	int ret;
>>>>>>  
>>>>>>  	if (!lradc->use_touchscreen)
>>>>>>  		return 0;
>>>>>>  
>>>>>> -	input = input_allocate_device();
>>>>>> +	input = devm_input_allocate_device(dev);
>>>>>>  	if (!input)
>>>>>>  		return -ENOMEM;
>>>>>>  
>>>>>> @@ -1134,11 +1133,8 @@ static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
>>>>>>  
>>>>>>  	lradc->ts_input = input;
>>>>>>  	input_set_drvdata(input, lradc);
>>>>>> -	ret = input_register_device(input);
>>>>>> -	if (ret)
>>>>>> -		input_free_device(lradc->ts_input);
>>>>>>  
>>>>>> -	return ret;
>>>>>> +	return input_register_device(input);
>>>>>>  }
>>>>>>  
>>>>>>  static void mxs_lradc_ts_unregister(struct mxs_lradc *lradc)
>>>>>>
>>>>> Nice find.
>>>>>
>>>>> Looks like at91_adc.c and exynos_adc.c suffer from the exact same issue.
>>>>> The leak looks a bit more severe on exynos even, exynos_adc_ts_init()
>>>>> could use a proper fail path. Do you want to send patches or shall I ?
>>>>>
>>>> As this has been there a long time I'm not going to rush it in as a fix.
>>> I did take a proper look today and it seems they do the right thing
>>> afterall. I checked them with kmemleak too to be sure.
>> thanks, input_unregister_device already free the memory.
>>
>> Sorry for the mess :-(
>>
>> I think it would be the best to remove / revert this patch.
> This one? Why exactly? Please elaborate some more, so it's possible to
> understand the reasoning :)
>
>

as you already pointed out this is not a memory leak, because
input_unregister_device free the input device. So the commit message is
incorrect.

This commit also simplifies the code but in this case we should also
remove input_unregister_device.

Regards
Stefan