ocxl: make ocxl_class constant

Now that the driver core allows for struct class to be in read-only
memory, we should make all 'class' structures declared at build time
placing them into read-only memory, instead of having to be dynamically
allocated at runtime.

Cc: Andrew Donnellan <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: [e-mail]
Acked-by: Frederic Barrat <[e-mail]>
Link: https://lore.kernel.org/r/2023102403-squirt-defraud-6c0c@gregkh
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/ocxl/file.c

···
 #define OCXL_NUM_MINORS 256 /* Total to reserve */
 
 static dev_t ocxl_dev;
-static struct class *ocxl_class;
 static DEFINE_MUTEX(minors_idr_lock);
 static struct idr minors_idr;
 
···
 	cdev_del(&info->cdev);
 }
 
+static char *ocxl_devnode(const struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "ocxl/%s", dev_name(dev));
+}
+
+static const struct class ocxl_class = {
+	.name =		"ocxl",
+	.devnode =	ocxl_devnode,
+};
+
 int ocxl_file_register_afu(struct ocxl_afu *afu)
 {
 	int minor;
···
 
 	info->dev.parent = &fn->dev;
 	info->dev.devt = MKDEV(MAJOR(ocxl_dev), minor);
-	info->dev.class = ocxl_class;
+	info->dev.class = &ocxl_class;
 	info->dev.release = info_release;
 
 	info->afu = afu;
···
 	device_unregister(&info->dev);
 }
 
-static char *ocxl_devnode(const struct device *dev, umode_t *mode)
-{
-	return kasprintf(GFP_KERNEL, "ocxl/%s", dev_name(dev));
-}
-
 int ocxl_file_init(void)
 {
 	int rc;
···
 		return rc;
 	}
 
-	ocxl_class = class_create("ocxl");
-	if (IS_ERR(ocxl_class)) {
+	rc = class_register(&ocxl_class);
+	if (rc) {
 		pr_err("Unable to create ocxl class\n");
 		unregister_chrdev_region(ocxl_dev, OCXL_NUM_MINORS);
-		return PTR_ERR(ocxl_class);
+		return rc;
 	}
 
-	ocxl_class->devnode = ocxl_devnode;
 	return 0;
 }
 
 void ocxl_file_exit(void)
 {
-	class_destroy(ocxl_class);
+	class_unregister(&ocxl_class);
 	unregister_chrdev_region(ocxl_dev, OCXL_NUM_MINORS);
 	idr_destroy(&minors_idr);
 }