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

[Russ Weight <russell.h.weight@intel.com>]

On 5/31/21 8:23 AM, Xu Yilun wrote:
> 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() ...

Thanks - I'll fix it

>>     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?

OK - I'll look at making this change.

>
>>  	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.

will do

>
>>   */
>> -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.

Sure -I'll look at doing this for both the fpga-mgr and fpga-region code.

- Russ
>
> 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