Re: [PATCH v4 3/3] fpga: region: Use standard dev_release for class driver

[Xu Yilun <yilun.xu@intel.com>]

On Fri, May 28, 2021 at 02:57:55PM -0700, Russ Weight wrote:
> The FPGA region class driver data structure is being treated as a
> managed resource instead of using standard dev_release call-back
> to release the class data structure. This change removes the
> managed resource code and combines the create() and register()
> functions into a single register() function.
> 
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> ---
> v4:
>   - Added the compat_id parameter to fpga_bridge_register() to ensure

A typo                           ...   fpga_region_register() ...

>     that the compat_id is set before the device_register() call.
>   - Modified the dfl_fpga_feature_devs_enumerate() function to restore
>     the fpga_region_register() call to the correct location.
> v3:
>   - Cleaned up comment header for fpga_region_register()
>   - Fix fpga_region_register() error return on ida_simple_get() failure
> v2:
>   - No changes
> ---
>  drivers/fpga/dfl-fme-region.c    |  12 ++--
>  drivers/fpga/dfl.c               |  12 ++--
>  drivers/fpga/fpga-region.c       | 106 +++++++------------------------
>  drivers/fpga/of-fpga-region.c    |  10 +--
>  include/linux/fpga/fpga-region.h |  13 ++--
>  5 files changed, 38 insertions(+), 115 deletions(-)
> 
> diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
> index 1eeb42af1012..9e44c623a5e9 100644
> --- a/drivers/fpga/dfl-fme-region.c
> +++ b/drivers/fpga/dfl-fme-region.c
> @@ -39,20 +39,16 @@ static int fme_region_probe(struct platform_device *pdev)
>  	if (IS_ERR(mgr))
>  		return -EPROBE_DEFER;
>  
> -	region = devm_fpga_region_create(dev, mgr, fme_region_get_bridges);
> -	if (!region) {
> -		ret = -ENOMEM;
> +	region = fpga_region_register(dev, mgr, mgr->compat_id,
> +				      fme_region_get_bridges);
> +	if (IS_ERR(region)) {
> +		ret = PTR_ERR(region);
>  		goto eprobe_mgr_put;
>  	}
>  
>  	region->priv = pdata;
> -	region->compat_id = mgr->compat_id;

I think the region->priv has the same issue as compat_id, could we
introduce a fpga_region_ops for fpga_region_register, wrapping all
input parameters, such as mgr, (*get_bridges)(), priv, compat_id?

>  	platform_set_drvdata(pdev, region);
>  
> -	ret = fpga_region_register(region);
> -	if (ret)
> -		goto eprobe_mgr_put;
> -
>  	dev_dbg(dev, "DFL FME FPGA Region probed\n");
>  
>  	return 0;
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 511b20ff35a3..6e628c07c1dc 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -1400,19 +1400,15 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
>  	if (!cdev)
>  		return ERR_PTR(-ENOMEM);
>  
> -	cdev->region = devm_fpga_region_create(info->dev, NULL, NULL);
> -	if (!cdev->region) {
> -		ret = -ENOMEM;
> -		goto free_cdev_exit;
> -	}
> -
>  	cdev->parent = info->dev;
>  	mutex_init(&cdev->lock);
>  	INIT_LIST_HEAD(&cdev->port_dev_list);
>  
> -	ret = fpga_region_register(cdev->region);
> -	if (ret)
> +	cdev->region = fpga_region_register(info->dev, NULL, NULL, NULL);
> +	if (IS_ERR(cdev->region)) {
> +		ret = PTR_ERR(cdev->region);
>  		goto free_cdev_exit;
> +	}
>  
>  	/* create and init build info for enumeration */
>  	binfo = devm_kzalloc(info->dev, sizeof(*binfo), GFP_KERNEL);
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index c3134b89c3fe..3d28880bf1cc 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -180,39 +180,38 @@ static struct attribute *fpga_region_attrs[] = {
>  ATTRIBUTE_GROUPS(fpga_region);
>  
>  /**
> - * fpga_region_create - alloc and init a struct fpga_region
> + * fpga_region_register - create and register a FPGA Region device
>   * @dev: device parent
>   * @mgr: manager that programs this region
> + * @compat_id: FPGA manager id for compatibility check.
>   * @get_bridges: optional function to get bridges to a list
>   *
> - * The caller of this function is responsible for freeing the resulting region
> - * struct with fpga_region_free().  Using devm_fpga_region_create() instead is
> - * recommended.
> - *
> - * Return: struct fpga_region or NULL
> + * Return struct fpga_region pointer on success, or ERR_PTR() on error.

Please also restore the doc format.

>   */
> -struct fpga_region
> -*fpga_region_create(struct device *dev,
> -		    struct fpga_manager *mgr,
> -		    int (*get_bridges)(struct fpga_region *))
> +struct fpga_region *
> +fpga_region_register(struct device *dev, struct fpga_manager *mgr,
> +		     struct fpga_compat_id *compat_id,
> +		     int (*get_bridges)(struct fpga_region *))
>  {
>  	struct fpga_region *region;
>  	int id, ret = 0;
>  
>  	region = kzalloc(sizeof(*region), GFP_KERNEL);
>  	if (!region)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>  
>  	id = ida_simple_get(&fpga_region_ida, 0, 0, GFP_KERNEL);
> -	if (id < 0)
> +	if (id < 0) {
> +		ret = id;
>  		goto err_free;
> +	}
>  
>  	region->mgr = mgr;
> +	region->compat_id = compat_id;
>  	region->get_bridges = get_bridges;
>  	mutex_init(&region->mutex);
>  	INIT_LIST_HEAD(&region->bridge_list);
>  
> -	device_initialize(&region->dev);
>  	region->dev.class = fpga_region_class;
>  	region->dev.parent = dev;
>  	region->dev.of_node = dev->of_node;
> @@ -222,6 +221,12 @@ struct fpga_region
>  	if (ret)
>  		goto err_remove;
>  
> +	ret = device_register(&region->dev);
> +	if (ret) {
> +		put_device(&region->dev);
> +		return ERR_PTR(ret);
> +	}
> +
>  	return region;
>  
>  err_remove:
> @@ -229,76 +234,7 @@ struct fpga_region
>  err_free:
>  	kfree(region);
>  
> -	return NULL;
> -}
> -EXPORT_SYMBOL_GPL(fpga_region_create);
> -
> -/**
> - * fpga_region_free - free a FPGA region created by fpga_region_create()
> - * @region: FPGA region
> - */
> -void fpga_region_free(struct fpga_region *region)
> -{
> -	ida_simple_remove(&fpga_region_ida, region->dev.id);
> -	kfree(region);
> -}
> -EXPORT_SYMBOL_GPL(fpga_region_free);
> -
> -static void devm_fpga_region_release(struct device *dev, void *res)
> -{
> -	struct fpga_region *region = *(struct fpga_region **)res;
> -
> -	fpga_region_free(region);
> -}
> -
> -/**
> - * devm_fpga_region_create - create and initialize a managed FPGA region struct
> - * @dev: device parent
> - * @mgr: manager that programs this region
> - * @get_bridges: optional function to get bridges to a list
> - *
> - * This function is intended for use in a FPGA region driver's probe function.
> - * After the region driver creates the region struct with
> - * devm_fpga_region_create(), it should register it with fpga_region_register().
> - * The region driver's remove function should call fpga_region_unregister().
> - * The region struct allocated with this function will be freed automatically on
> - * driver detach.  This includes the case of a probe function returning error
> - * before calling fpga_region_register(), the struct will still get cleaned up.
> - *
> - * Return: struct fpga_region or NULL
> - */
> -struct fpga_region
> -*devm_fpga_region_create(struct device *dev,
> -			 struct fpga_manager *mgr,
> -			 int (*get_bridges)(struct fpga_region *))
> -{
> -	struct fpga_region **ptr, *region;
> -
> -	ptr = devres_alloc(devm_fpga_region_release, sizeof(*ptr), GFP_KERNEL);
> -	if (!ptr)
> -		return NULL;
> -
> -	region = fpga_region_create(dev, mgr, get_bridges);
> -	if (!region) {
> -		devres_free(ptr);
> -	} else {
> -		*ptr = region;
> -		devres_add(dev, ptr);
> -	}
> -
> -	return region;
> -}
> -EXPORT_SYMBOL_GPL(devm_fpga_region_create);
> -
> -/**
> - * fpga_region_register - register a FPGA region
> - * @region: FPGA region
> - *
> - * Return: 0 or -errno
> - */
> -int fpga_region_register(struct fpga_region *region)
> -{
> -	return device_add(&region->dev);
> +	return ERR_PTR(ret);
>  }
>  EXPORT_SYMBOL_GPL(fpga_region_register);
>  
> @@ -316,6 +252,10 @@ EXPORT_SYMBOL_GPL(fpga_region_unregister);
>  
>  static void fpga_region_dev_release(struct device *dev)
>  {
> +	struct fpga_region *region = to_fpga_region(dev);
> +
> +	ida_simple_remove(&fpga_region_ida, region->dev.id);
> +	kfree(region);
>  }
>  
>  /**
> diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
> index e405309baadc..c115e5fc0c62 100644
> --- a/drivers/fpga/of-fpga-region.c
> +++ b/drivers/fpga/of-fpga-region.c
> @@ -405,16 +405,12 @@ static int of_fpga_region_probe(struct platform_device *pdev)
>  	if (IS_ERR(mgr))
>  		return -EPROBE_DEFER;
>  
> -	region = devm_fpga_region_create(dev, mgr, of_fpga_region_get_bridges);
> -	if (!region) {
> -		ret = -ENOMEM;
> +	region = fpga_region_register(dev, mgr, NULL, of_fpga_region_get_bridges);
> +	if (IS_ERR(region)) {
> +		ret = PTR_ERR(region);
>  		goto eprobe_mgr_put;
>  	}
>  
> -	ret = fpga_region_register(region);
> -	if (ret)
> -		goto eprobe_mgr_put;
> -
>  	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
>  	platform_set_drvdata(pdev, region);
>  
> diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-region.h
> index 27cb706275db..1e4c2dc7a63b 100644
> --- a/include/linux/fpga/fpga-region.h
> +++ b/include/linux/fpga/fpga-region.h
> @@ -37,15 +37,10 @@ struct fpga_region *fpga_region_class_find(
>  
>  int fpga_region_program_fpga(struct fpga_region *region);
>  
> -struct fpga_region
> -*fpga_region_create(struct device *dev, struct fpga_manager *mgr,
> -		    int (*get_bridges)(struct fpga_region *));
> -void fpga_region_free(struct fpga_region *region);
> -int fpga_region_register(struct fpga_region *region);
> +struct fpga_region *
> +fpga_region_register(struct device *dev, struct fpga_manager *mgr,
> +		     struct fpga_compat_id *compat_id,
> +		     int (*get_bridges)(struct fpga_region *));

Same concern as fpga_mgr_register, shall we introduce a fpga_region_ops
to wrap mgr, (*get_bridges), compat_id and priv? So we don't have to change
all the callers everytime we need a new input for fpga_region.

Thanks,
Yilun

>  void fpga_region_unregister(struct fpga_region *region);
>  
> -struct fpga_region
> -*devm_fpga_region_create(struct device *dev, struct fpga_manager *mgr,
> -			int (*get_bridges)(struct fpga_region *));
> -
>  #endif /* _FPGA_REGION_H */
> -- 
> 2.25.1