Input: make sure input interfaces pin parent input devices

Recent driver core change causes references to parent devices being
dropped early, at device_del() time, as opposed to when all children
are freed. This causes oops in evdev with grabbed devices. Take the
reference to the parent input device ourselves to ensure that it
stays around long enough.

Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/evdev.c

···
 {
 	struct evdev *evdev = container_of(dev, struct evdev, dev);
 
+	input_put_device(evdev->handle.dev);
 	kfree(evdev);
 }
 
···
 	evdev_hangup(evdev);
 	evdev_remove_chrdev(evdev);
 
-	if (evdev->grab)
-		evdev_ungrab(evdev, evdev->grab);
-
 	/* evdev is marked dead so no one else accesses evdev->open */
 	if (evdev->open) {
 		input_flush_device(handle, NULL);
···
 	evdev->exist = 1;
 	evdev->minor = minor;
 
-	evdev->handle.dev = dev;
+	evdev->handle.dev = input_get_device(dev);
 	evdev->handle.name = evdev->name;
 	evdev->handle.handler = handler;
 	evdev->handle.private = evdev;

drivers/input/joydev.c

···
 {
 	struct joydev *joydev = container_of(dev, struct joydev, dev);
 
+	input_put_device(joydev->handle.dev);
 	kfree(joydev);
 }
 
···
 	joydev->minor = minor;
 
 	joydev->exist = 1;
-	joydev->handle.dev = dev;
+	joydev->handle.dev = input_get_device(dev);
 	joydev->handle.name = joydev->name;
 	joydev->handle.handler = handler;
 	joydev->handle.private = joydev;

drivers/input/mousedev.c

···
 {
 	struct mousedev *mousedev = container_of(dev, struct mousedev, dev);
 
+	input_put_device(mousedev->handle.dev);
 	kfree(mousedev);
 }
 
···
 
 	mousedev->minor = minor;
 	mousedev->exist = 1;
-	mousedev->handle.dev = dev;
+	mousedev->handle.dev = input_get_device(dev);
 	mousedev->handle.name = mousedev->name;
 	mousedev->handle.handler = handler;
 	mousedev->handle.private = mousedev;

include/linux/input.h

···
 
 static inline struct input_dev *input_get_device(struct input_dev *dev)
 {
-	return to_input_dev(get_device(&dev->dev));
+	return dev ? to_input_dev(get_device(&dev->dev)) : NULL;
 }
 
 static inline void input_put_device(struct input_dev *dev)
 {
-	put_device(&dev->dev);
+	if (dev)
+		put_device(&dev->dev);
 }
 
 static inline void *input_get_drvdata(struct input_dev *dev)