linux-kernel - Re: [PATCHv3 2/9] extcon: Add devm_extcon_dev_allocate/free to manage the resource of extcon device

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Message-ID: <CAGTfZH3bZk1_Yrhig_uWDtF5+6u+ePfuqJa9rDCWBJ1GH+AmkQ@mail.gmail.com>
Date:	Fri, 25 Apr 2014 00:03:31 +0900
From:	Chanwoo Choi <cwchoi00@...il.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Chanwoo Choi <cw00.choi@...sung.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
	gg@...mlogic.co.uk, Kishon Vijay Abraham I <kishon@...com>,
	ckeepax@...nsource.wolfsonmicro.com,
	Mark Brown <broonie@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCHv3 2/9] extcon: Add devm_extcon_dev_allocate/free to manage
 the resource of extcon device

Hi,

On Thu, Apr 24, 2014 at 11:44 PM, Felipe Balbi <balbi@...com> wrote:
> On Thu, Apr 24, 2014 at 09:34:50PM +0900, Chanwoo Choi wrote:
>> This patch add device managed devm_extcon_dev_{allocate,free} to automatically
>> free the memory of extcon_dev structure without handling free operation.
>>
>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>> ---
>>  drivers/extcon/extcon-class.c | 70 +++++++++++++++++++++++++++++++++++--------
>>  include/linux/extcon.h        | 11 +++++++
>>  2 files changed, 69 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c
>> index bec66d4..f369168 100644
>> --- a/drivers/extcon/extcon-class.c
>> +++ b/drivers/extcon/extcon-class.c
>> @@ -604,6 +604,64 @@ void extcon_dev_free(struct extcon_dev *edev)
>>  }
>>  EXPORT_SYMBOL_GPL(extcon_dev_free);
>>
>> +static int devm_extcon_dev_match(struct device *dev, void *res, void *data)
>> +{
>> +     struct extcon_dev **r = res;
>> +
>> +     if (!r || !*r) {
>> +             WARN_ON(!r || !*r);
>> +             return 0;
>> +     }
>> +
>> +     return *r == data;
>> +}
>> +
>> +static void devm_extcon_dev_release(struct device *dev, void *res)
>> +{
>> +     extcon_dev_free(*(struct extcon_dev **)res);
>> +}
>> +
>> +/**
>> + * devm_extcon_dev_allocate - Allocate managed extcon device
>> + * @dev:             device owning the extcon device being created
>> + * @supported_cable: Array of supported cable names ending with NULL.
>> + *                   If supported_cable is NULL, cable name related APIs
>> + *                   are disabled.
>> + *
>> + * This function manages automatically the memory of extcon device using device
>> + * resource management and simplify the control of freeing the memory of extcon
>> + * device.
>> + *
>> + * Returns the pointer memory of allocated extcon_dev if success or NULL if fail
>> + */
>> +struct extcon_dev *devm_extcon_dev_allocate(struct device *dev,
>> +                                         const char **supported_cable)
>> +{
>> +     struct extcon_dev **ptr, *edev;
>> +
>> +     ptr = devres_alloc(devm_extcon_dev_release, sizeof(*ptr), GFP_KERNEL);
>> +     if (!ptr)
>> +             return NULL;
>
> if this fails you return NULL;
>
>> +
>> +     edev = extcon_dev_allocate(supported_cable);
>
> if this fails, you return -ENOMEM. Not very nice, if you ask me.

I'll fix it as following:

If  both extcon_dev_allocate() and devm_excon_dev_allocate() failed to
allocate memory,
two functions would return NULL pointer instead of  ERR_PTR(-ENOMEM).

Thanks,
Chanwoo Choi
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