s390/vmur: make vmur_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 vmur_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>
Link: https://lore.kernel.org/r/20240305-class_cleanup-s390-v1-2-c4ff1ec49ffd@marliere.net
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Author: rbmarliere

drivers/s390/char/vmur.c

@@ -48,7 +48,9 @@ MODULE_DESCRIPTION("s390 z/VM virtual unit record device driver");
 MODULE_LICENSE("GPL");
 
 static dev_t ur_first_dev_maj_min;
-static struct class *vmur_class;
+static const struct class vmur_class = {
+	.name = "vmur",
+};
 static struct debug_info *vmur_dbf;
 
 /* We put the device's record length (for writes) in the driver_info field */
@@ -912,7 +914,7 @@ static int ur_set_online(struct ccw_device *cdev)
 		goto fail_free_cdev;
 	}
 
-	urd->device = device_create(vmur_class, &cdev->dev,
+	urd->device = device_create(&vmur_class, &cdev->dev,
 				    urd->char_device->dev, NULL, "%s", node_id);
 	if (IS_ERR(urd->device)) {
 		rc = PTR_ERR(urd->device);
@@ -958,7 +960,7 @@ static int ur_set_offline_force(struct ccw_device *cdev, int force)
 		/* Work not run yet - need to release reference here */
 		urdev_put(urd);
 	}
-	device_destroy(vmur_class, urd->char_device->dev);
+	device_destroy(&vmur_class, urd->char_device->dev);
 	cdev_del(urd->char_device);
 	urd->char_device = NULL;
 	rc = 0;
@@ -1022,11 +1024,9 @@ static int __init ur_init(void)
 
 	debug_set_level(vmur_dbf, 6);
 
-	vmur_class = class_create("vmur");
-	if (IS_ERR(vmur_class)) {
-		rc = PTR_ERR(vmur_class);
+	rc = class_register(&vmur_class);
+	if (rc)
 		goto fail_free_dbf;
-	}
 
 	rc = ccw_driver_register(&ur_driver);
 	if (rc)
@@ -1046,7 +1046,7 @@ static int __init ur_init(void)
 fail_unregister_driver:
 	ccw_driver_unregister(&ur_driver);
 fail_class_destroy:
-	class_destroy(vmur_class);
+	class_unregister(&vmur_class);
 fail_free_dbf:
 	debug_unregister(vmur_dbf);
 	return rc;
@@ -1056,7 +1056,7 @@ static void __exit ur_exit(void)
 {
 	unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
 	ccw_driver_unregister(&ur_driver);
-	class_destroy(vmur_class);
+	class_unregister(&vmur_class);
 	debug_unregister(vmur_dbf);
 	pr_info("%s unloaded.\n", ur_banner);
 }