// SPDX-License-Identifier: GPL-2.0/* * All the USB notify logic * * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de> * * notifier functions originally based on those in kernel/sys.c * but fixed up to not be so broken. * * Released under the GPLv2 only. */  #include <linux/kernel.h>#include <linux/export.h>#include <linux/notifier.h>#include <linux/usb.h>#include <linux/mutex.h>#include "usb.h" static BLOCKING_NOTIFIER_HEAD(usb_notifier_list); /** * usb_register_notify - register a notifier callback whenever a usb change happens * @nb: pointer to the notifier block for the callback events. * * These changes are either USB devices or busses being added or removed. */void usb_register_notify(struct notifier_block *nb){	blocking_notifier_chain_register(&usb_notifier_list, nb);}EXPORT_SYMBOL_GPL(usb_register_notify); /** * usb_unregister_notify - unregister a notifier callback * @nb: pointer to the notifier block for the callback events. * * usb_register_notify() must have been previously called for this function * to work properly. */void usb_unregister_notify(struct notifier_block *nb){	blocking_notifier_chain_unregister(&usb_notifier_list, nb);}EXPORT_SYMBOL_GPL(usb_unregister_notify);  void usb_notify_add_device(struct usb_device *udev){	blocking_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);} void usb_notify_remove_device(struct usb_device *udev){	blocking_notifier_call_chain(&usb_notifier_list,			USB_DEVICE_REMOVE, udev);} void usb_notify_add_bus(struct usb_bus *ubus){	blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);} void usb_notify_remove_bus(struct usb_bus *ubus){	blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);}