linux-kernel - Re: [PATCHv4 2/9] extcon: Add devm_extcon_dev_allocate/free to manage the resource of extcon device

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Message-ID: <20140425151434.GF29632@saruman.home>
Date:	Fri, 25 Apr 2014 10:14:34 -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: [PATCHv4 2/9] extcon: Add devm_extcon_dev_allocate/free to
 manage the resource of extcon device

On Fri, Apr 25, 2014 at 09:42:17AM +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>

apart for a couple comments below:

Reviewed-by: Felipe Balbi <balbi@...com>

> ---
>  drivers/extcon/extcon-class.c | 72 +++++++++++++++++++++++++++++++++++--------
>  include/linux/extcon.h        | 11 +++++++
>  2 files changed, 71 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c
> index 654ed52..24ede8b 100644
> --- a/drivers/extcon/extcon-class.c
> +++ b/drivers/extcon/extcon-class.c
> @@ -601,6 +601,66 @@ 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);

you can use WARN_ON() inside the if statement:

	if (WARN_ON(!r || !*r))
		return 0;

> +		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 ERR_PTR(err) 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 ERR_PTR(-ENOMEM);
> +
> +	edev = extcon_dev_allocate(supported_cable);
> +	if (IS_ERR(edev)) {
> +		devres_free(ptr);
> +		return ERR_PTR(-ENOMEM);

edev already is an error pointer, you might want to propagate that error
instead of rewriting it here.

> +	}
> +
> +	*ptr = edev;
> +	devres_add(dev, ptr);
> +
> +	return edev;
> +}
> +EXPORT_SYMBOL_GPL(devm_extcon_dev_allocate);
> +
> +void devm_extcon_dev_free(struct device *dev, struct extcon_dev *edev)
> +{
> +	WARN_ON(devres_release(dev, devm_extcon_dev_release,
> +			       devm_extcon_dev_match, edev));
> +}
> +EXPORT_SYMBOL_GPL(devm_extcon_dev_free);
> +
>  /**
>   * extcon_dev_register() - Register a new extcon device
>   * @edev	: the new extcon device (should be allocated before calling)
> @@ -860,18 +920,6 @@ static void devm_extcon_dev_unreg(struct device *dev, void *res)
>  	extcon_dev_unregister(*(struct extcon_dev **)res);
>  }
>  
> -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;
> -}
> -
>  /**
>   * devm_extcon_dev_register() - Resource-managed extcon_dev_register()
>   * @dev:	device to allocate extcon device
> diff --git a/include/linux/extcon.h b/include/linux/extcon.h
> index f4fc983..3fd831b 100644
> --- a/include/linux/extcon.h
> +++ b/include/linux/extcon.h
> @@ -196,6 +196,9 @@ extern struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name);
>   */
>  extern struct extcon_dev *extcon_dev_allocate(const char **cables);
>  extern void extcon_dev_free(struct extcon_dev *edev);
> +extern struct extcon_dev *devm_extcon_dev_allocate(struct device *dev,
> +						   const char **cables);
> +extern void devm_extcon_dev_free(struct device *dev, struct extcon_dev *edev);
>  
>  /*
>   * get/set/update_state access the 32b encoded state value, which represents
> @@ -280,6 +283,14 @@ static inline struct extcon_dev *extcon_dev_allocate(const char **cables)
>  
>  static inline void extcon_dev_free(struct extcon_dev *edev) { }
>  
> +static inline struct extcon_dev *devm_extcon_dev_allocate(struct device *dev,
> +							  const char **cables)
> +{
> +	return ERR_PTR(-ENOMEM);

-ENOSYS

-- 
balbi

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