Revert "USB: usb-skeleton.c: fix open/disconnect race"

This reverts commit 26c71a79cade5ccad80e0752cd82f3518df48fb3.

It's not needed, to quote Ming Lei:
	Looks you have queued the patch into your tree, but just now I
	find the patch is not needed at all, since we have had
	minor_rwsem(drivers/usb/core/file.c) for this purpose, please
	drop the patch, sorry for it.

Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/usb-skeleton.c

@@ -27,8 +27,6 @@
 #define USB_SKEL_VENDOR_ID	0xfff0
 #define USB_SKEL_PRODUCT_ID	0xfff0
 
-static DEFINE_MUTEX(skel_mutex);
-
 /* table of devices that work with this driver */
 static const struct usb_device_id skel_table[] = {
 	{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
@@ -101,25 +99,18 @@ static int skel_open(struct inode *inode, struct file *file)
 		goto exit;
 	}
 
-	mutex_lock(&skel_mutex);
 	dev = usb_get_intfdata(interface);
 	if (!dev) {
-		mutex_unlock(&skel_mutex);
 		retval = -ENODEV;
 		goto exit;
 	}
 
 	/* increment our usage count for the device */
 	kref_get(&dev->kref);
-	mutex_unlock(&skel_mutex);
 
 	/* lock the device to allow correctly handling errors
 	 * in resumption */
 	mutex_lock(&dev->io_mutex);
-	if (!dev->interface) {
-		retval = -ENODEV;
-		goto out_err;
-	}
 
 	retval = usb_autopm_get_interface(interface);
 	if (retval)
@@ -127,11 +118,7 @@ static int skel_open(struct inode *inode, struct file *file)
 
 	/* save our object in the file's private structure */
 	file->private_data = dev;
-
-out_err:
 	mutex_unlock(&dev->io_mutex);
-	if (retval)
-		kref_put(&dev->kref, skel_delete);
 
 exit:
 	return retval;
@@ -611,6 +598,7 @@ static void skel_disconnect(struct usb_interface *interface)
 	int minor = interface->minor;
 
 	dev = usb_get_intfdata(interface);
+	usb_set_intfdata(interface, NULL);
 
 	/* give back our minor */
 	usb_deregister_dev(interface, &skel_class);
@@ -622,12 +610,8 @@ static void skel_disconnect(struct usb_interface *interface)
 
 	usb_kill_anchored_urbs(&dev->submitted);
 
-	mutex_lock(&skel_mutex);
-	usb_set_intfdata(interface, NULL);
-
 	/* decrement our usage count */
 	kref_put(&dev->kref, skel_delete);
-	mutex_unlock(&skel_mutex);
 
 	dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 }