char: lp: make lp_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the lp_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at load time.

Cc: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230620143751.578239-12-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: ivanorlov2206

drivers/char/lp.c

@@ -145,7 +145,9 @@ static struct lp_struct lp_table[LP_NO];
 static int port_num[LP_NO];
 
 static unsigned int lp_count = 0;
-static struct class *lp_class;
+static const struct class lp_class = {
+	.name = "printer",
+};
 
 #ifdef CONFIG_LP_CONSOLE
 static struct parport *console_registered;
@@ -932,7 +934,7 @@ static int lp_register(int nr, struct parport *port)
 	if (reset)
 		lp_reset(nr);
 
-	device_create(lp_class, port->dev, MKDEV(LP_MAJOR, nr), NULL,
+	device_create(&lp_class, port->dev, MKDEV(LP_MAJOR, nr), NULL,
 		      "lp%d", nr);
 
 	printk(KERN_INFO "lp%d: using %s (%s).\n", nr, port->name,
@@ -1004,7 +1006,7 @@ static void lp_detach(struct parport *port)
 		if (port_num[n] == port->number) {
 			port_num[n] = -1;
 			lp_count--;
-			device_destroy(lp_class, MKDEV(LP_MAJOR, n));
+			device_destroy(&lp_class, MKDEV(LP_MAJOR, n));
 			parport_unregister_device(lp_table[n].dev);
 		}
 	}
@@ -1049,11 +1051,9 @@ static int __init lp_init(void)
 		return -EIO;
 	}
 
-	lp_class = class_create("printer");
-	if (IS_ERR(lp_class)) {
-		err = PTR_ERR(lp_class);
+	err = class_register(&lp_class);
+	if (err)
 		goto out_reg;
-	}
 
 	if (parport_register_driver(&lp_driver)) {
 		printk(KERN_ERR "lp: unable to register with parport\n");
@@ -1072,7 +1072,7 @@ static int __init lp_init(void)
 	return 0;
 
 out_class:
-	class_destroy(lp_class);
+	class_unregister(&lp_class);
 out_reg:
 	unregister_chrdev(LP_MAJOR, "lp");
 	return err;
@@ -1115,7 +1115,7 @@ static void lp_cleanup_module(void)
 #endif
 
 	unregister_chrdev(LP_MAJOR, "lp");
-	class_destroy(lp_class);
+	class_unregister(&lp_class);
 }
 
 __setup("lp=", lp_setup);