Re: [RFC PATCH v3] clk: Use new helper in managed functions

[Marc Gonzalez]

I'm aware that my timing sucked with respect to the merge window.
I am grateful for any comments, remarks, suggestions.
Regards.

On 24/01/2020 17:16, Marc Gonzalez wrote:

> Introduce devm_add() to factorize devres_alloc/devres_add calls.
> 
> Using that helper produces simpler code, and smaller object size.
> E.g. with gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu:
> 
>     text	   data	    bss	    dec	    hex	filename
> -   1708	     80	      0	   1788	    6fc	drivers/clk/clk-devres.o
> +   1524	     80	      0	   1604	    644	drivers/clk/clk-devres.o
> 
> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@xxxxxxx>
> ---
> Differences from v2 to v3
> x Make devm_add() return an error-code rather than the raw data pointer
>   (in case devres_alloc ever returns an ERR_PTR) as suggested by Geert
> x Provide a variadic version devm_vadd() to work with structs as suggested
>   by Geert
> x Don't use nested ifs in clk_devm* implementations (hopefully simpler
>   code logic to follow) as suggested by Geert
> 
> Questions:
> x This patch might need to be split in two? (Introduce the new API, then use it)
> x Convert other subsystems to show the value of this proposal?
> x Maybe comment the API usage somewhere
> ---
>  drivers/base/devres.c    | 15 ++++++
>  drivers/clk/clk-devres.c | 99 ++++++++++++++--------------------------
>  include/linux/device.h   |  3 ++
>  3 files changed, 53 insertions(+), 64 deletions(-)
> 
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 0bbb328bd17f..b2603789755b 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -685,6 +685,21 @@ int devres_release_group(struct device *dev, void *id)
>  }
>  EXPORT_SYMBOL_GPL(devres_release_group);
>  
> +int devm_add(struct device *dev, dr_release_t func, void *arg, size_t size)
> +{
> +	void *data = devres_alloc(func, size, GFP_KERNEL);
> +
> +	if (!data) {
> +		func(dev, arg);
> +		return -ENOMEM;
> +	}
> +
> +	memcpy(data, arg, size);
> +	devres_add(dev, data);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_add);
> +
>  /*
>   * Custom devres actions allow inserting a simple function call
>   * into the teadown sequence.
> diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
> index be160764911b..1da69d273855 100644
> --- a/drivers/clk/clk-devres.c
> +++ b/drivers/clk/clk-devres.c
> @@ -4,26 +4,22 @@
>  #include <linux/export.h>
>  #include <linux/gfp.h>
>  
> -static void devm_clk_release(struct device *dev, void *res)
> +static void my_clk_put(struct device *dev, void *res)
>  {
>  	clk_put(*(struct clk **)res);
>  }
>  
>  struct clk *devm_clk_get(struct device *dev, const char *id)
>  {
> -	struct clk **ptr, *clk;
> -
> -	ptr = devres_alloc(devm_clk_release, sizeof(*ptr), GFP_KERNEL);
> -	if (!ptr)
> -		return ERR_PTR(-ENOMEM);
> -
> -	clk = clk_get(dev, id);
> -	if (!IS_ERR(clk)) {
> -		*ptr = clk;
> -		devres_add(dev, ptr);
> -	} else {
> -		devres_free(ptr);
> -	}
> +	int ret;
> +	struct clk *clk = clk_get(dev, id);
> +
> +	if (IS_ERR(clk))
> +		return clk;
> +
> +	ret = devm_add(dev, my_clk_put, &clk, sizeof(clk));
> +	if (ret)
> +		return ERR_PTR(ret);
>  
>  	return clk;
>  }
> @@ -40,14 +36,14 @@ struct clk *devm_clk_get_optional(struct device *dev, const char *id)
>  }
>  EXPORT_SYMBOL(devm_clk_get_optional);
>  
> -struct clk_bulk_devres {
> -	struct clk_bulk_data *clks;
> +struct clk_bulk_args {
>  	int num_clks;
> +	struct clk_bulk_data *clks;
>  };
>  
> -static void devm_clk_bulk_release(struct device *dev, void *res)
> +static void my_clk_bulk_put(struct device *dev, void *res)
>  {
> -	struct clk_bulk_devres *devres = res;
> +	struct clk_bulk_args *devres = res;
>  
>  	clk_bulk_put(devres->num_clks, devres->clks);
>  }
> @@ -55,25 +51,17 @@ static void devm_clk_bulk_release(struct device *dev, void *res)
>  static int __devm_clk_bulk_get(struct device *dev, int num_clks,
>  			       struct clk_bulk_data *clks, bool optional)
>  {
> -	struct clk_bulk_devres *devres;
>  	int ret;
>  
> -	devres = devres_alloc(devm_clk_bulk_release,
> -			      sizeof(*devres), GFP_KERNEL);
> -	if (!devres)
> -		return -ENOMEM;
> -
>  	if (optional)
>  		ret = clk_bulk_get_optional(dev, num_clks, clks);
>  	else
>  		ret = clk_bulk_get(dev, num_clks, clks);
> -	if (!ret) {
> -		devres->clks = clks;
> -		devres->num_clks = num_clks;
> -		devres_add(dev, devres);
> -	} else {
> -		devres_free(devres);
> -	}
> +
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_vadd(dev, my_clk_bulk_put, clk_bulk_args, num_clks, clks);
>  
>  	return ret;
>  }
> @@ -95,24 +83,15 @@ EXPORT_SYMBOL_GPL(devm_clk_bulk_get_optional);
>  int __must_check devm_clk_bulk_get_all(struct device *dev,
>  				       struct clk_bulk_data **clks)
>  {
> -	struct clk_bulk_devres *devres;
>  	int ret;
> +	int num_clks = clk_bulk_get_all(dev, clks);
>  
> -	devres = devres_alloc(devm_clk_bulk_release,
> -			      sizeof(*devres), GFP_KERNEL);
> -	if (!devres)
> -		return -ENOMEM;
> -
> -	ret = clk_bulk_get_all(dev, &devres->clks);
> -	if (ret > 0) {
> -		*clks = devres->clks;
> -		devres->num_clks = ret;
> -		devres_add(dev, devres);
> -	} else {
> -		devres_free(devres);
> -	}
> +	if (num_clks <= 0)
> +		return num_clks;
>  
> -	return ret;
> +	ret = devm_vadd(dev, my_clk_bulk_put, clk_bulk_args, num_clks, *clks);
> +
> +	return ret ? : num_clks;
>  }
>  EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all);
>  
> @@ -128,30 +107,22 @@ static int devm_clk_match(struct device *dev, void *res, void *data)
>  
>  void devm_clk_put(struct device *dev, struct clk *clk)
>  {
> -	int ret;
> -
> -	ret = devres_release(dev, devm_clk_release, devm_clk_match, clk);
> -
> -	WARN_ON(ret);
> +	WARN_ON(devres_release(dev, my_clk_put, devm_clk_match, clk));
>  }
>  EXPORT_SYMBOL(devm_clk_put);
>  
>  struct clk *devm_get_clk_from_child(struct device *dev,
>  				    struct device_node *np, const char *con_id)
>  {
> -	struct clk **ptr, *clk;
> -
> -	ptr = devres_alloc(devm_clk_release, sizeof(*ptr), GFP_KERNEL);
> -	if (!ptr)
> -		return ERR_PTR(-ENOMEM);
> -
> -	clk = of_clk_get_by_name(np, con_id);
> -	if (!IS_ERR(clk)) {
> -		*ptr = clk;
> -		devres_add(dev, ptr);
> -	} else {
> -		devres_free(ptr);
> -	}
> +	int ret;
> +	struct clk *clk = of_clk_get_by_name(np, con_id);
> +
> +	if (IS_ERR(clk))
> +		return clk;
> +
> +	ret = devm_add(dev, my_clk_put, &clk, sizeof(clk));
> +	if (ret)
> +		return ERR_PTR(ret);
>  
>  	return clk;
>  }
> diff --git a/include/linux/device.h b/include/linux/device.h
> index e226030c1df3..9f18582fc0f9 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -969,6 +969,9 @@ void __iomem *devm_of_iomap(struct device *dev,
>  			    struct device_node *node, int index,
>  			    resource_size_t *size);
>  
> +int devm_add(struct device *dev, dr_release_t func, void *arg, size_t size);
> +#define devm_vadd(dev, func, type, args...) \
> +	devm_add(dev, func, &(struct type){args}, sizeof(struct type))
>  /* allows to add/remove a custom action to devres stack */
>  int devm_add_action(struct device *dev, void (*action)(void *), void *data);
>  void devm_remove_action(struct device *dev, void (*action)(void *), void *data);