+
+static struct notifier_block *usb_notifier_list;
+static DECLARE_MUTEX(usb_notifier_lock);
+
+static void usb_notifier_chain_register(struct notifier_block **list,
+ struct notifier_block *n)
+{
+ down(&usb_notifier_lock);
+ while (*list) {
+ if (n->priority > (*list)->priority)
+ break;
+ list = &((*list)->next);
+ }
+ n->next = *list;
+ *list = n;
+ up(&usb_notifier_lock);
+}
+
+static void usb_notifier_chain_unregister(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ down(&usb_notifier_lock);
+ while ((*nl)!=NULL) {
+ if ((*nl)==n) {
+ *nl = n->next;
+ goto exit;
+ }
+ nl=&((*nl)->next);
+ }
+exit:
+ up(&usb_notifier_lock);
+}
+
+static int usb_notifier_call_chain(struct notifier_block **n,
+ unsigned long val, void *v)
+{
+ int ret=NOTIFY_DONE;
+ struct notifier_block *nb = *n;
+
+ down(&usb_notifier_lock);
+ while (nb) {
+ ret = nb->notifier_call(nb,val,v);
+ if (ret&NOTIFY_STOP_MASK) {
+ goto exit;
+ }
+ nb = nb->next;
+ }
+exit:
+ up(&usb_notifier_lock);
+ return ret;
+}