Re: [PATCH v2 3/3] fpga: region: make fpga_region_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_region_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-region.c | 23 +++++++++++------------
>   1 file changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index ccf6fdab1360..6abd8a154047 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -16,7 +16,7 @@
>   #include <linux/spinlock.h>
>   
>   static DEFINE_IDA(fpga_region_ida);
> -static struct class *fpga_region_class;
> +static const struct class fpga_region_class;
>   
>   struct fpga_region *
>   fpga_region_class_find(struct device *start, const void *data,
> @@ -24,7 +24,7 @@ fpga_region_class_find(struct device *start, const void *data,
>   {
>   	struct device *dev;
>   
> -	dev = class_find_device(fpga_region_class, start, data, match);
> +	dev = class_find_device(&fpga_region_class, start, data, match);
>   	if (!dev)
>   		return NULL;
>   
> @@ -216,7 +216,7 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
>   	mutex_init(&region->mutex);
>   	INIT_LIST_HEAD(&region->bridge_list);
>   
> -	region->dev.class = fpga_region_class;
> +	region->dev.class = &fpga_region_class;
>   	region->dev.parent = parent;
>   	region->dev.of_node = parent->of_node;
>   	region->dev.id = id;
> @@ -287,25 +287,24 @@ static void fpga_region_dev_release(struct device *dev)
>   	kfree(region);
>   }
>   
> +static const struct class fpga_region_class = {
> +	.name = "fpga_region",
> +	.dev_groups = fpga_region_groups,
> +	.dev_release = fpga_region_dev_release,
> +};
> +
>   /**
>    * fpga_region_init - init function for fpga_region class
>    * Creates the fpga_region class and registers a reconfig notifier.
>    */
>   static int __init fpga_region_init(void)
>   {
> -	fpga_region_class = class_create("fpga_region");
> -	if (IS_ERR(fpga_region_class))
> -		return PTR_ERR(fpga_region_class);
> -
> -	fpga_region_class->dev_groups = fpga_region_groups;
> -	fpga_region_class->dev_release = fpga_region_dev_release;
> -
> -	return 0;
> +	return class_register(&fpga_region_class);
>   }
>   
>   static void __exit fpga_region_exit(void)
>   {
> -	class_destroy(fpga_region_class);
> +	class_unregister(&fpga_region_class);
>   	ida_destroy(&fpga_region_ida);
>   }
>   
And I forgot the changelog here.

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