Re: [PATCH] drm/amdkfd: make kfd_class constant

[Felix Kuehling]

On 2024-03-05 7:15, Ricardo B. Marliere wrote:
> Since commit 43a7206b0963 ("driver core: class: make class_register() take
> a const *"), the driver core allows for struct class to be in read-only
> memory, so move the kfd_class structure to be declared at build time
> placing it into read-only memory, instead of having to be dynamically
> allocated at boot time.
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>

The patch looks good to me. Do you want me to apply this to Alex's 
amd-staging-drm-next?

Reviewed-by: Felix Kuehling <felix.kuehling@xxxxxxx>


> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 21 +++++++++++----------
>   1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> index f030cafc5a0a..dfa8c69532d4 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> @@ -63,8 +63,10 @@ static const struct file_operations kfd_fops = {
>   };
>   
>   static int kfd_char_dev_major = -1;
> -static struct class *kfd_class;
>   struct device *kfd_device;
> +static const struct class kfd_class = {
> +	.name = kfd_dev_name,
> +};
>   
>   static inline struct kfd_process_device *kfd_lock_pdd_by_id(struct kfd_process *p, __u32 gpu_id)
>   {
> @@ -94,14 +96,13 @@ int kfd_chardev_init(void)
>   	if (err < 0)
>   		goto err_register_chrdev;
>   
> -	kfd_class = class_create(kfd_dev_name);
> -	err = PTR_ERR(kfd_class);
> -	if (IS_ERR(kfd_class))
> +	err = class_register(&kfd_class);
> +	if (err)
>   		goto err_class_create;
>   
> -	kfd_device = device_create(kfd_class, NULL,
> -					MKDEV(kfd_char_dev_major, 0),
> -					NULL, kfd_dev_name);
> +	kfd_device = device_create(&kfd_class, NULL,
> +				   MKDEV(kfd_char_dev_major, 0),
> +				   NULL, kfd_dev_name);
>   	err = PTR_ERR(kfd_device);
>   	if (IS_ERR(kfd_device))
>   		goto err_device_create;
> @@ -109,7 +110,7 @@ int kfd_chardev_init(void)
>   	return 0;
>   
>   err_device_create:
> -	class_destroy(kfd_class);
> +	class_unregister(&kfd_class);
>   err_class_create:
>   	unregister_chrdev(kfd_char_dev_major, kfd_dev_name);
>   err_register_chrdev:
> @@ -118,8 +119,8 @@ int kfd_chardev_init(void)
>   
>   void kfd_chardev_exit(void)
>   {
> -	device_destroy(kfd_class, MKDEV(kfd_char_dev_major, 0));
> -	class_destroy(kfd_class);
> +	device_destroy(&kfd_class, MKDEV(kfd_char_dev_major, 0));
> +	class_unregister(&kfd_class);
>   	unregister_chrdev(kfd_char_dev_major, kfd_dev_name);
>   	kfd_device = NULL;
>   }
>
> ---
> base-commit: 8bc75586ea01f1c645063d3472c115ecab03e76c
> change-id: 20240305-class_cleanup-drm-amd-bdc7255b7540
>
> Best regards,