Re: [PATCH v9 3/3] fpga: region: Use standard dev_release for class driver

From: Russ Weight <russell.h.weight@intel.com>
To: Xu Yilun <yilun.xu@intel.com>
Cc: mdf@kernel.org, linux-fpga@vger.kernel.org, trix@redhat.com,
	lgoncalv@redhat.com, hao.wu@intel.com, matthew.gerlach@intel.com,
	richard.gong@intel.com
Subject: Re: [PATCH v9 3/3] fpga: region: Use standard dev_release for class driver
Date: Tue, 6 Jul 2021 16:08:56 -0700	[thread overview]
Message-ID: <07c112f0-49d3-1a5d-e77f-7cca8cd0d689@intel.com> (raw)
In-Reply-To: <20210701055145.GC96355@yilunxu-OptiPlex-7050>


On 6/30/21 10:51 PM, Xu Yilun wrote:
> On Wed, Jun 30, 2021 at 06:37:33PM -0700, Russ Weight wrote:
>> The FPGA region class driver data structure is being treated as a
>> managed resource instead of using the standard dev_release call-back
>> function to release the class data structure. This change removes the
>> managed resource code and combines the create() and register()
>> functions into a single register() or register_simple() function.
>>
>> The register() function accepts an info data structure to provide
>> flexibility in passing optional parameters. The register_simple()
>> function supports the current parameter list for users that don't
>> require the use of optional parameters.
> Please update the commit message, others are good to me.

I'll fix it. Thanks!
- Russ
>
> Thanks,
> Yilun
>
>> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
>> Reviewed-by: Xu Yilun <yilun.xu@intel.com>
>> ---
>> v9:
>>   - Cleaned up documentation for the FPGA Region register functions
>>   - Renamed fpga_region_register() to fpga_region_register_full()
>>   - Renamed fpga_region_register_simple() to fpga_region_register()
>> v8:
>>   - Added reviewed-by tag.
>>   - Updated Documentation/driver-api/fpga/fpga-region.rst documentation.
>> v7:
>>   - Update the commit message to describe the new parameters for the
>>     fpga_region_register() function and to mention the
>>     fpga_region_register_simple() function.
>>   - Fix function prototypes in header file to rename dev to parent.
>>   - Some cleanup of comments.
>>   - Update function defintions/prototypes to apply const to the new info
>>     parameter.
>>   - Verify a non-null info pointer in the register() functions.
>> v6:
>>   - Moved FPGA manager optional parameters out of the ops structure and
>>     back into the FPGA Region structure.
>>   - Changed fpga_region_register() parameters to accept an info data
>>     structure to provide flexibility in passing optional parameters.
>>   - Added fpga_region_register_simple() functions to support current
>>     parameters for users that don't require the use of optional parameters.
>> v5:
>>   - Rebased on top of recently accepted patches.
>>   - Created the fpga_region_ops data structure which is optionally passed
>>     to fpga_region_register(). compat_id, the get_bridges() pointer, and
>>     the priv pointer are included in the fpga_region_ops structure.
>> v4:
>>   - Added the compat_id parameter to fpga_region_register() to ensure
>>     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
>> ---
>>  Documentation/driver-api/fpga/fpga-region.rst |   8 +-
>>  drivers/fpga/dfl-fme-region.c                 |  17 ++-
>>  drivers/fpga/dfl.c                            |  12 +-
>>  drivers/fpga/fpga-region.c                    | 119 +++++++-----------
>>  drivers/fpga/of-fpga-region.c                 |  10 +-
>>  include/linux/fpga/fpga-region.h              |  36 ++++--
>>  6 files changed, 91 insertions(+), 111 deletions(-)
>>
>> diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst
>> index 2636a27c11b2..904518190bb4 100644
>> --- a/Documentation/driver-api/fpga/fpga-region.rst
>> +++ b/Documentation/driver-api/fpga/fpga-region.rst
>> @@ -46,8 +46,10 @@ API to add a new FPGA region
>>  ----------------------------
>>  
>>  * struct fpga_region - The FPGA region struct
>> -* devm_fpga_region_create() - Allocate and init a region struct
>> -* fpga_region_register() -  Register an FPGA region
>> +* fpga_region_register_full() -  Create and register an FPGA region using the
>> +  fpga_region_info structure to provide the full flexibility of options
>> +* fpga_region_register() -  Create and register an FPGA region using standard
>> +  arguments
>>  * fpga_region_unregister() -  Unregister an FPGA region
>>  
>>  The FPGA region's probe function will need to get a reference to the FPGA
>> @@ -76,7 +78,7 @@ following APIs to handle building or tearing down that list.
>>     :functions: fpga_region
>>  
>>  .. kernel-doc:: drivers/fpga/fpga-region.c
>> -   :functions: devm_fpga_region_create
>> +   :functions: fpga_region_register_full
>>  
>>  .. kernel-doc:: drivers/fpga/fpga-region.c
>>     :functions: fpga_region_register
>> diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
>> index 1eeb42af1012..4aebde0a7f1c 100644
>> --- a/drivers/fpga/dfl-fme-region.c
>> +++ b/drivers/fpga/dfl-fme-region.c
>> @@ -30,6 +30,7 @@ static int fme_region_get_bridges(struct fpga_region *region)
>>  static int fme_region_probe(struct platform_device *pdev)
>>  {
>>  	struct dfl_fme_region_pdata *pdata = dev_get_platdata(&pdev->dev);
>> +	struct fpga_region_info info = { 0 };
>>  	struct device *dev = &pdev->dev;
>>  	struct fpga_region *region;
>>  	struct fpga_manager *mgr;
>> @@ -39,20 +40,18 @@ 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;
>> +	info.mgr = mgr;
>> +	info.compat_id = mgr->compat_id;
>> +	info.get_bridges = fme_region_get_bridges;
>> +	info.priv = pdata;
>> +	region = fpga_region_register_full(dev, &info);
>> +	if (IS_ERR(region)) {
>> +		ret = PTR_ERR(region);
>>  		goto eprobe_mgr_put;
>>  	}
>>  
>> -	region->priv = pdata;
>> -	region->compat_id = mgr->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..3905995ef6d5 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);
>> +	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 a4838715221f..8af108a383e0 100644
>> --- a/drivers/fpga/fpga-region.c
>> +++ b/drivers/fpga/fpga-region.c
>> @@ -180,39 +180,42 @@ static struct attribute *fpga_region_attrs[] = {
>>  ATTRIBUTE_GROUPS(fpga_region);
>>  
>>  /**
>> - * fpga_region_create - alloc and init a struct fpga_region
>> + * fpga_region_register_full - create and register an FPGA Region device
>>   * @parent: device parent
>> - * @mgr: manager that programs this region
>> - * @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.
>> + * @info: parameters for FPGA Region
>>   *
>> - * Return: struct fpga_region or NULL
>> + * Return: struct fpga_region or ERR_PTR()
>>   */
>> -struct fpga_region
>> -*fpga_region_create(struct device *parent,
>> -		    struct fpga_manager *mgr,
>> -		    int (*get_bridges)(struct fpga_region *))
>> +struct fpga_region *
>> +fpga_region_register_full(struct device *parent, const struct fpga_region_info *info)
>>  {
>>  	struct fpga_region *region;
>>  	int id, ret = 0;
>>  
>> +	if (!info) {
>> +		dev_err(parent,
>> +			"Attempt to register without required info structure\n");
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>>  	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 = info->mgr;
>> +	region->compat_id = info->compat_id;
>> +	region->priv = info->priv;
>> +	region->get_bridges = info->get_bridges;
>>  
>> -	region->mgr = mgr;
>> -	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 = parent;
>>  	region->dev.of_node = parent->of_node;
>> @@ -222,6 +225,12 @@ 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 +238,32 @@ struct fpga_region
>>  err_free:
>>  	kfree(region);
>>  
>> -	return NULL;
>> -}
>> -EXPORT_SYMBOL_GPL(fpga_region_create);
>> -
>> -/**
>> - * fpga_region_free - free an 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);
>> +	return ERR_PTR(ret);
>>  }
>> +EXPORT_SYMBOL_GPL(fpga_region_register_full);
>>  
>>  /**
>> - * devm_fpga_region_create - create and initialize a managed FPGA region struct
>> + * fpga_region_register - create and register an FPGA Region device
>>   * @parent: 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 an 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.
>> + * This simple version of the register should be sufficient for most users.
>> + * The fpga_region_register_full() function is available for users that need to
>> + * pass additional, optional parameters.
>>   *
>> - * Return: struct fpga_region or NULL
>> + * Return: struct fpga_region or ERR_PTR()
>>   */
>> -struct fpga_region
>> -*devm_fpga_region_create(struct device *parent,
>> -			 struct fpga_manager *mgr,
>> -			 int (*get_bridges)(struct fpga_region *))
>> +struct fpga_region *
>> +fpga_region_register(struct device *parent, 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;
>> +	struct fpga_region_info info = { 0 };
>>  
>> -	region = fpga_region_create(parent, mgr, get_bridges);
>> -	if (!region) {
>> -		devres_free(ptr);
>> -	} else {
>> -		*ptr = region;
>> -		devres_add(parent, ptr);
>> -	}
>> +	info.mgr = mgr;
>> +	info.get_bridges = get_bridges;
>>  
>> -	return region;
>> -}
>> -EXPORT_SYMBOL_GPL(devm_fpga_region_create);
>> -
>> -/**
>> - * fpga_region_register - register an FPGA region
>> - * @region: FPGA region
>> - *
>> - * Return: 0 or -errno
>> - */
>> -int fpga_region_register(struct fpga_region *region)
>> -{
>> -	return device_add(&region->dev);
>> +	return fpga_region_register_full(parent, &info);
>>  }
>>  EXPORT_SYMBOL_GPL(fpga_region_register);
>>  
>> @@ -316,6 +281,10 @@ 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 e3c25576b6b9..9c662db1c508 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, 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..ae111beeffba 100644
>> --- a/include/linux/fpga/fpga-region.h
>> +++ b/include/linux/fpga/fpga-region.h
>> @@ -7,6 +7,27 @@
>>  #include <linux/fpga/fpga-mgr.h>
>>  #include <linux/fpga/fpga-bridge.h>
>>  
>> +struct fpga_region;
>> +
>> +/**
>> + * struct fpga_region_info - collection of parameters an FPGA Region
>> + * @mgr: fpga region manager
>> + * @compat_id: FPGA region id for compatibility check.
>> + * @priv: fpga region private data
>> + * @get_bridges: optional function to get bridges to a list
>> + *
>> + * fpga_region_info contains parameters for the register function. These
>> + * are separated into an info structure because they some are optional
>> + * others could be added to in the future. The info structure facilitates
>> + * maintaining a stable API.
>> + */
>> +struct fpga_region_info {
>> +	struct fpga_manager *mgr;
>> +	struct fpga_compat_id *compat_id;
>> +	void *priv;
>> +	int (*get_bridges)(struct fpga_region *region);
>> +};
>> +
>>  /**
>>   * struct fpga_region - FPGA Region structure
>>   * @dev: FPGA Region device
>> @@ -37,15 +58,12 @@ 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);
>> -void fpga_region_unregister(struct fpga_region *region);
>> +struct fpga_region *
>> +fpga_region_register_full(struct device *parent, const struct fpga_region_info *info);
>>  
>> -struct fpga_region
>> -*devm_fpga_region_create(struct device *dev, struct fpga_manager *mgr,
>> -			int (*get_bridges)(struct fpga_region *));
>> +struct fpga_region *
>> +fpga_region_register(struct device *parent, struct fpga_manager *mgr,
>> +		     int (*get_bridges)(struct fpga_region *));
>> +void fpga_region_unregister(struct fpga_region *region);
>>  
>>  #endif /* _FPGA_REGION_H */
>> -- 
>> 2.25.1