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Commit df718962 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: cancel pending Set-Config requests if userspace gets there first 



This patch (as1195) eliminates a potential problem identified by
Oliver Neukum.  When a driver queues an asynchronous Set-Config
request using usb_driver_set_configuration(), the request should be
cancelled if userspace changes the configuration first.  The patch
introduces a linked list of pending async Set-Config requests, and
uses it to invalidate the requests for a particular device whenever
that device's configuration is set.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 6fd9086a

drivers/usb/core/message.c

+38 −4
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include "hcd.h"	/* for usbcore internals */

#include "usb.h"



static void cancel_async_set_config(struct usb_device *udev);



struct api_context {

	struct completion	done;

	int			status;
@@ -1636,6 +1638,9 @@ free_interfaces: 
	if (dev->state != USB_STATE_ADDRESS)

		usb_disable_device(dev, 1);	/* Skip ep0 */



	/* Get rid of pending async Set-Config requests for this device */

	cancel_async_set_config(dev);



	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),

			      USB_REQ_SET_CONFIGURATION, 0, configuration, 0,

			      NULL, 0, USB_CTRL_SET_TIMEOUT);
@@ -1725,10 +1730,14 @@ free_interfaces: 
	return 0;

}



static LIST_HEAD(set_config_list);

static DEFINE_SPINLOCK(set_config_lock);



struct set_config_request {

	struct usb_device	*udev;

	int			config;

	struct work_struct	work;

	struct list_head	node;

};



/* Worker routine for usb_driver_set_configuration() */
@@ -1736,14 +1745,35 @@ static void driver_set_config_work(struct work_struct *work) 
{

	struct set_config_request *req =

		container_of(work, struct set_config_request, work);

	struct usb_device *udev = req->udev;



	usb_lock_device(udev);

	spin_lock(&set_config_lock);

	list_del(&req->node);

	spin_unlock(&set_config_lock);



	usb_lock_device(req->udev);

	usb_set_configuration(req->udev, req->config);

	usb_unlock_device(req->udev);

	usb_put_dev(req->udev);

	if (req->config >= -1)		/* Is req still valid? */

		usb_set_configuration(udev, req->config);

	usb_unlock_device(udev);

	usb_put_dev(udev);

	kfree(req);

}



/* Cancel pending Set-Config requests for a device whose configuration

 * was just changed

 */

static void cancel_async_set_config(struct usb_device *udev)

{

	struct set_config_request *req;



	spin_lock(&set_config_lock);

	list_for_each_entry(req, &set_config_list, node) {

		if (req->udev == udev)

			req->config = -999;	/* Mark as cancelled */

	}

	spin_unlock(&set_config_lock);

}



/**

 * usb_driver_set_configuration - Provide a way for drivers to change device configurations

 * @udev: the device whose configuration is being updated
@@ -1775,6 +1805,10 @@ int usb_driver_set_configuration(struct usb_device *udev, int config) 
	req->config = config;

	INIT_WORK(&req->work, driver_set_config_work);



	spin_lock(&set_config_lock);

	list_add(&req->node, &set_config_list);

	spin_unlock(&set_config_lock);



	usb_get_dev(udev);

	schedule_work(&req->work);

	return 0;