drivers/usb/core/notify.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * All the USB notify logic
   4  *
   5  * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
   6  *
   7  * notifier functions originally based on those in kernel/sys.c
   8  * but fixed up to not be so broken.
   9  *
  10  * Released under the GPLv2 only.
  11  */
  12
  13
  14 #include <linux/kernel.h>
  15 #include <linux/export.h>
  16 #include <linux/notifier.h>
  17 #include <linux/usb.h>
  18 #include <linux/mutex.h>
  19 #include "usb.h"
  20
  21 static BLOCKING_NOTIFIER_HEAD(usb_notifier_list);
  22
  23 /**
  24  * usb_register_notify - register a notifier callback whenever a usb change happens
  25  * @nb: pointer to the notifier block for the callback events.
  26  *
  27  * These changes are either USB devices or busses being added or removed.
  28  */
  29 void usb_register_notify(struct notifier_block *nb)
  30 {
  31         blocking_notifier_chain_register(&usb_notifier_list, nb);
  32 }
  33 EXPORT_SYMBOL_GPL(usb_register_notify);
  34
  35 /**
  36  * usb_unregister_notify - unregister a notifier callback
  37  * @nb: pointer to the notifier block for the callback events.
  38  *
  39  * usb_register_notify() must have been previously called for this function
  40  * to work properly.
  41  */
  42 void usb_unregister_notify(struct notifier_block *nb)
  43 {
  44         blocking_notifier_chain_unregister(&usb_notifier_list, nb);
  45 }
  46 EXPORT_SYMBOL_GPL(usb_unregister_notify);
  47
  48
  49 void usb_notify_add_device(struct usb_device *udev)
  50 {
  51         blocking_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
  52 }
  53
  54 void usb_notify_remove_device(struct usb_device *udev)
  55 {
  56         /* Protect against simultaneous usbfs open */
  57         mutex_lock(&usbfs_mutex);
  58         blocking_notifier_call_chain(&usb_notifier_list,
  59                         USB_DEVICE_REMOVE, udev);
  60         mutex_unlock(&usbfs_mutex);
  61 }
  62
  63 void usb_notify_add_bus(struct usb_bus *ubus)
  64 {
  65         blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
  66 }
  67
  68 void usb_notify_remove_bus(struct usb_bus *ubus)
  69 {
  70         blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
  71 }