[PATCH 6/6] USB: file.c: make usb class a static const structure

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Ivan Orlov <ivan.orlov0322@gmail.com>

Now that the driver core allows for struct class to be in read-only
memory, remove the class field of the usb_class structure and
create the usbmisc_class static class structure declared at build time
which places it into read-only memory, instead of having it to be
dynamically allocated at load time.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/core/file.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c
index c4ed3310e069..0e16a9c048dd 100644
--- a/drivers/usb/core/file.c
+++ b/drivers/usb/core/file.c
@@ -59,7 +59,6 @@ static const struct file_operations usb_fops = {
 
 static struct usb_class {
 	struct kref kref;
-	struct class *class;
 } *usb_class;
 
 static char *usb_devnode(const struct device *dev, umode_t *mode)
@@ -72,6 +71,11 @@ static char *usb_devnode(const struct device *dev, umode_t *mode)
 	return drv->devnode(dev, mode);
 }
 
+static struct class usbmisc_class = {
+	.name		= "usbmisc",
+	.devnode	= usb_devnode,
+};
+
 static int init_usb_class(void)
 {
 	int result = 0;
@@ -88,15 +92,12 @@ static int init_usb_class(void)
 	}
 
 	kref_init(&usb_class->kref);
-	usb_class->class = class_create("usbmisc");
-	if (IS_ERR(usb_class->class)) {
-		result = PTR_ERR(usb_class->class);
-		printk(KERN_ERR "class_create failed for usb devices\n");
+	result = class_register(&usbmisc_class);
+	if (result) {
 		kfree(usb_class);
 		usb_class = NULL;
 		goto exit;
 	}
-	usb_class->class->devnode = usb_devnode;
 
 exit:
 	return result;
@@ -105,7 +106,7 @@ static int init_usb_class(void)
 static void release_usb_class(struct kref *kref)
 {
 	/* Ok, we cheat as we know we only have one usb_class */
-	class_destroy(usb_class->class);
+	class_unregister(&usbmisc_class);
 	kfree(usb_class);
 	usb_class = NULL;
 }
@@ -200,7 +201,7 @@ int usb_register_dev(struct usb_interface *intf,
 
 	/* create a usb class device for this usb interface */
 	snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
-	intf->usb_dev = device_create(usb_class->class, &intf->dev,
+	intf->usb_dev = device_create(&usbmisc_class, &intf->dev,
 				      MKDEV(USB_MAJOR, minor), class_driver,
 				      "%s", kbasename(name));
 	if (IS_ERR(intf->usb_dev)) {
@@ -234,7 +235,7 @@ void usb_deregister_dev(struct usb_interface *intf,
 		return;
 
 	dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
-	device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
+	device_destroy(&usbmisc_class, MKDEV(USB_MAJOR, intf->minor));
 
 	down_write(&minor_rwsem);
 	usb_minors[intf->minor] = NULL;
-- 
2.41.0