drm/amdkfd: make kfd_class constant

Since commit 43a7206 ("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@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: rbmarliere

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)
 {
@@ -94,22 +96,21 @@ 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;
 
 	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;
 }