USB: roles: make role_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the role_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at load time.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230620094412.508580-7-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/roles/class.c

@@ -14,7 +14,9 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 
-static struct class *role_class;
+static const struct class role_class = {
+	.name = "usb_role",
+};
 
 struct usb_role_switch {
 	struct device dev;
@@ -95,7 +97,7 @@ static void *usb_role_switch_match(const struct fwnode_handle *fwnode, const cha
 	if (id && !fwnode_property_present(fwnode, id))
 		return NULL;
 
-	dev = class_find_device_by_fwnode(role_class, fwnode);
+	dev = class_find_device_by_fwnode(&role_class, fwnode);
 
 	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
 }
@@ -111,7 +113,7 @@ usb_role_switch_is_parent(struct fwnode_handle *fwnode)
 		return NULL;
 	}
 
-	dev = class_find_device_by_fwnode(role_class, parent);
+	dev = class_find_device_by_fwnode(&role_class, parent);
 	fwnode_handle_put(parent);
 	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
 }
@@ -191,7 +193,7 @@ usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
 	if (!fwnode)
 		return NULL;
 
-	dev = class_find_device_by_fwnode(role_class, fwnode);
+	dev = class_find_device_by_fwnode(&role_class, fwnode);
 	if (dev)
 		WARN_ON(!try_module_get(dev->parent->driver->owner));
 
@@ -338,7 +340,7 @@ usb_role_switch_register(struct device *parent,
 
 	sw->dev.parent = parent;
 	sw->dev.fwnode = desc->fwnode;
-	sw->dev.class = role_class;
+	sw->dev.class = &role_class;
 	sw->dev.type = &usb_role_dev_type;
 	dev_set_drvdata(&sw->dev, desc->driver_data);
 	dev_set_name(&sw->dev, "%s-role-switch",
@@ -392,14 +394,13 @@ EXPORT_SYMBOL_GPL(usb_role_switch_get_drvdata);
 
 static int __init usb_roles_init(void)
 {
-	role_class = class_create("usb_role");
-	return PTR_ERR_OR_ZERO(role_class);
+	return class_register(&role_class);
 }
 subsys_initcall(usb_roles_init);
 
 static void __exit usb_roles_exit(void)
 {
-	class_destroy(role_class);
+	class_unregister(&role_class);
 }
 module_exit(usb_roles_exit);