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ffed60971f
Commit 4a2a8a2cce ("usbfs: private mutex for open, release, and
remove") is now obsolete. The commit was created back when we had
to handle both usbfs device nodes and the old usbdevfs filesystem
(/proc/bus/usb/), but usbdevfs no longer exists.
This means there's no longer any need to hold a mutex during two
separate removal operations (and thus during an entire notifier chain
call). Furthermore, the one remaining remove/release pair doesn't
race with open thanks to the synchronization provided by the device
model core in bus_find_device(). Remove and release don't race with
each other because they both run with the device lock held.
The upshot is that usbfs_mutex isn't needed any more. This patch
removes it entirely.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* All the USB notify logic
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*
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* (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
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*
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* notifier functions originally based on those in kernel/sys.c
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* but fixed up to not be so broken.
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*
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* Released under the GPLv2 only.
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/notifier.h>
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#include <linux/usb.h>
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#include <linux/mutex.h>
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#include "usb.h"
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static BLOCKING_NOTIFIER_HEAD(usb_notifier_list);
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/**
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* usb_register_notify - register a notifier callback whenever a usb change happens
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* @nb: pointer to the notifier block for the callback events.
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*
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* These changes are either USB devices or busses being added or removed.
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*/
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void usb_register_notify(struct notifier_block *nb)
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{
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blocking_notifier_chain_register(&usb_notifier_list, nb);
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}
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EXPORT_SYMBOL_GPL(usb_register_notify);
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/**
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* usb_unregister_notify - unregister a notifier callback
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* @nb: pointer to the notifier block for the callback events.
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*
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* usb_register_notify() must have been previously called for this function
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* to work properly.
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*/
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void usb_unregister_notify(struct notifier_block *nb)
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{
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blocking_notifier_chain_unregister(&usb_notifier_list, nb);
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}
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EXPORT_SYMBOL_GPL(usb_unregister_notify);
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void usb_notify_add_device(struct usb_device *udev)
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{
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blocking_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
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}
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void usb_notify_remove_device(struct usb_device *udev)
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{
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blocking_notifier_call_chain(&usb_notifier_list,
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USB_DEVICE_REMOVE, udev);
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}
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void usb_notify_add_bus(struct usb_bus *ubus)
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{
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blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
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}
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void usb_notify_remove_bus(struct usb_bus *ubus)
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{
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blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
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}
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