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: <20140424144458.GG26661@saruman.home>
Date:	Thu, 24 Apr 2014 09:44:58 -0500
From:	Felipe Balbi <balbi@...com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
CC:	<linux-kernel@...r.kernel.org>, <myungjoo.ham@...sung.com>,
	<balbi@...com>, <gg@...mlogic.co.uk>, <kishon@...com>,
	<ckeepax@...nsource.wolfsonmicro.com>, <broonie@...nel.org>,
	<k.kozlowski@...sung.com>, <kyungmin.park@...sung.com>
Subject: Re: [PATCHv3 2/9] extcon: Add devm_extcon_dev_allocate/free to
 manage the resource of extcon device

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.

-- 
balbi

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