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

From: [email-masked] (Stefan Wahren)
Date: Tue, 19 Apr 2016 08:33:17 +0200

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.

Stefan

>
>> I suspect no platform is probing and removing it enough to get a significant
>> amount of memory leaked.
>>
>> Good to clear it up though!
>>
>> Applied to the togreg branch of iio.git, initially pushed out as testing for
>> the autobuilders to play with it.
>>
>> Thanks,
>>
>> Jonathan
>>
>