Commit 79c36a70 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: idmouse: simplify disconnect handling 



Since commit d4ead16f ("USB: prevent char device open/deregister
race") core prevents further calls to open() after usb_deregister_dev()
returns so there's no need to use the interface data for
synchronisation.

This effectively reverts commit 54d2bc06 ("USB: fix locking in
idmouse") with respect to the open-disconnect race.

Note that the driver already uses a present flag to suppress I/O post
disconnect (even if all USB I/O take place at open).

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191105103638.4929-2-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e76b3bf7

drivers/usb/misc/idmouse.c

+2 −18
Original line number Diff line number Diff line
@@ -60,7 +60,6 @@ static const struct usb_device_id idmouse_table[] = { 
	USB_TYPE_VENDOR | USB_RECIP_ENDPOINT | USB_DIR_OUT, value, index, NULL, 0, 1000)



MODULE_DEVICE_TABLE(usb, idmouse_table);

static DEFINE_MUTEX(open_disc_mutex);



/* structure to hold all of our device specific stuff */

struct usb_idmouse {
@@ -227,17 +226,13 @@ static int idmouse_open(struct inode *inode, struct file *file) 
	if (!interface)

		return -ENODEV;



	mutex_lock(&open_disc_mutex);

	/* get the device information block from the interface */

	dev = usb_get_intfdata(interface);

	if (!dev) {

		mutex_unlock(&open_disc_mutex);

	if (!dev)

		return -ENODEV;

	}



	/* lock this device */

	mutex_lock(&dev->lock);

	mutex_unlock(&open_disc_mutex);



	/* check if already open */

	if (dev->open) {
@@ -280,14 +275,12 @@ static int idmouse_release(struct inode *inode, struct file *file) 
	if (dev == NULL)

		return -ENODEV;



	mutex_lock(&open_disc_mutex);

	/* lock our device */

	mutex_lock(&dev->lock);



	/* are we really open? */

	if (dev->open <= 0) {

		mutex_unlock(&dev->lock);

		mutex_unlock(&open_disc_mutex);

		return -ENODEV;

	}
@@ -296,11 +289,9 @@ static int idmouse_release(struct inode *inode, struct file *file) 
	if (!dev->present) {

		/* the device was unplugged before the file was released */

		mutex_unlock(&dev->lock);

		mutex_unlock(&open_disc_mutex);

		idmouse_delete(dev);

	} else {

		mutex_unlock(&dev->lock);

		mutex_unlock(&open_disc_mutex);

	}

	return 0;

}
@@ -379,7 +370,6 @@ static int idmouse_probe(struct usb_interface *interface, 
	if (result) {

		/* something prevented us from registering this device */

		dev_err(&interface->dev, "Unable to allocate minor number.\n");

		usb_set_intfdata(interface, NULL);

		idmouse_delete(dev);

		return result;

	}
@@ -392,19 +382,13 @@ static int idmouse_probe(struct usb_interface *interface, 


static void idmouse_disconnect(struct usb_interface *interface)

{

	struct usb_idmouse *dev;



	/* get device structure */

	dev = usb_get_intfdata(interface);

	struct usb_idmouse *dev = usb_get_intfdata(interface);



	/* give back our minor */

	usb_deregister_dev(interface, &idmouse_class);



	mutex_lock(&open_disc_mutex);

	usb_set_intfdata(interface, NULL);

	/* lock the device */

	mutex_lock(&dev->lock);

	mutex_unlock(&open_disc_mutex);



	/* prevent device read, write and ioctl */

	dev->present = 0;

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