Re: [PATCH v2 2/3] fpga: fpga-mgr: make fpga_mgr_class a static const structure

[Ivan Orlov <ivan.orlov0322@xxxxxxxxx>]

On 8/11/23 11:30, Ivan Orlov wrote:
> Now that the driver core allows for struct class to be in read-only
> memory, move the fpga_mgr_class structure to be declared at build time
> placing it into read-only memory, instead of having to be dynamically
> allocated at boot time.
>
> Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ivan Orlov <ivan.orlov0322@xxxxxxxxx>
> ---
>   drivers/fpga/fpga-mgr.c | 25 ++++++++++++-------------
>   1 file changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
> index eb583f86a0b9..06651389c592 100644
> --- a/drivers/fpga/fpga-mgr.c
> +++ b/drivers/fpga/fpga-mgr.c
> @@ -19,7 +19,7 @@
>   #include <linux/highmem.h>
>   
>   static DEFINE_IDA(fpga_mgr_ida);
> -static struct class *fpga_mgr_class;
> +static const struct class fpga_mgr_class;
>   
>   struct fpga_mgr_devres {
>   	struct fpga_manager *mgr;
> @@ -693,7 +693,7 @@ static int fpga_mgr_dev_match(struct device *dev, const void *data)
>    */
>   struct fpga_manager *fpga_mgr_get(struct device *dev)
>   {
> -	struct device *mgr_dev = class_find_device(fpga_mgr_class, NULL, dev,
> +	struct device *mgr_dev = class_find_device(&fpga_mgr_class, NULL, dev,
>   						   fpga_mgr_dev_match);
>   	if (!mgr_dev)
>   		return ERR_PTR(-ENODEV);
> @@ -713,7 +713,7 @@ struct fpga_manager *of_fpga_mgr_get(struct device_node *node)
>   {
>   	struct device *dev;
>   
> -	dev = class_find_device_by_of_node(fpga_mgr_class, node);
> +	dev = class_find_device_by_of_node(&fpga_mgr_class, node);
>   	if (!dev)
>   		return ERR_PTR(-ENODEV);
>   
> @@ -809,7 +809,7 @@ fpga_mgr_register_full(struct device *parent, const struct fpga_manager_info *in
>   	mgr->priv = info->priv;
>   	mgr->compat_id = info->compat_id;
>   
> -	mgr->dev.class = fpga_mgr_class;
> +	mgr->dev.class = &fpga_mgr_class;
>   	mgr->dev.groups = mops->groups;
>   	mgr->dev.parent = parent;
>   	mgr->dev.of_node = parent->of_node;
> @@ -967,23 +967,22 @@ static void fpga_mgr_dev_release(struct device *dev)
>   	kfree(mgr);
>   }
>   
> +static const struct class fpga_mgr_class = {
> +	.name = "fpga_manager",
> +	.dev_groups = fpga_mgr_groups,
> +	.dev_release = fpga_mgr_dev_release,
> +};
> +
>   static int __init fpga_mgr_class_init(void)
>   {
>   	pr_info("FPGA manager framework\n");
>   
> -	fpga_mgr_class = class_create("fpga_manager");
> -	if (IS_ERR(fpga_mgr_class))
> -		return PTR_ERR(fpga_mgr_class);
> -
> -	fpga_mgr_class->dev_groups = fpga_mgr_groups;
> -	fpga_mgr_class->dev_release = fpga_mgr_dev_release;
> -
> -	return 0;
> +	return class_register(&fpga_mgr_class);
>   }
>   
>   static void __exit fpga_mgr_class_exit(void)
>   {
> -	class_destroy(fpga_mgr_class);
> +	class_unregister(&fpga_mgr_class);
>   	ida_destroy(&fpga_mgr_ida);
>   }
>   
And I forgot the changelog here.

V1 -> V2:
- Add forward declaration of fpga_mgr_class
- Move definition of fpga_mgr_class to more logical place