linux-kernel - Re: [PATCH] regulator: core: Fix memory leak in regulator_resolve

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Message-ID: <55A61C0E.4040707@osg.samsung.com>
Date:	Wed, 15 Jul 2015 10:38:38 +0200
From:	Javier Martinez Canillas <javier@....samsung.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: core: Fix memory leak in
 regulator_resolve_supply()

Hello Krzysztof,

Thanks a lot for your feedback.

On 07/15/2015 10:01 AM, Krzysztof Kozlowski wrote:
> 2015-07-14 23:21 GMT+09:00 Javier Martinez Canillas <javier@....samsung.com>:
>> The regulator_resolve_supply() function calls set_supply() which in turn
>> calls create_regulator() to allocate a supply regulator.
>>
>> If an error occurs after set_supply() succeeded, the allocated regulator
>> has to be freed before propagating the error code.
>>
>> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
>>
>> ---
>>
>>  drivers/regulator/core.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
>> index 68b616580533..325c0f5c13ca 100644
>> --- a/drivers/regulator/core.c
>> +++ b/drivers/regulator/core.c
>> @@ -109,6 +109,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
>>  static struct regulator *create_regulator(struct regulator_dev *rdev,
>>                                           struct device *dev,
>>                                           const char *supply_name);
>> +static void _regulator_put(struct regulator *regulator);
>>
>>  static const char *rdev_get_name(struct regulator_dev *rdev)
>>  {
>> @@ -1402,8 +1403,11 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
>>         /* Cascade always-on state to supply */
>>         if (_regulator_is_enabled(rdev)) {
>>                 ret = regulator_enable(rdev->supply);
>> -               if (ret < 0)
>> +               if (ret < 0) {
>> +                       if (rdev->supply)
>> +                               _regulator_put(rdev->supply);
> 
> The _regulator_put() reverts more work than create_regulator() did,
> e.g.: module_put and rdev->open_count--. Maybe you need a
> destroy_regulator() function?
>

Yes, it reverts more work than create_regulator() but the intention is to
revert what set_supply() did. If you look at the set_supply() function,
it does supply_rdev->open_count++.

I did indeed missed the module_put() but now looking at the code again, I
wonder if the problem is not that set_supply() is missing a try_module_get()
to be consistent with what the _regulator_get() function does.
 
> Best regards,
> Krzysztof
>

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America
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