Commit 7c5b971d authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: iowarrior: drop redundant disconnect mutex 



Drop the redundant disconnect mutex which was introduced after the
open-disconnect race had been addressed generally in USB core by commit
d4ead16f ("USB: prevent char device open/deregister race").

Specifically, the rw-semaphore in core guarantees that all calls to
open() will have completed and that no new calls to open() will occur
after usb_deregister_dev() returns. Hence there is no need use the
driver data as an inverted disconnected flag.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009104846.5925-5-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b5f8d468

drivers/usb/misc/iowarrior.c

+2 −15
Original line number Diff line number Diff line
@@ -58,7 +58,6 @@ MODULE_LICENSE("GPL"); 
static DEFINE_MUTEX(iowarrior_mutex);



static struct usb_driver iowarrior_driver;

static DEFINE_MUTEX(iowarrior_open_disc_lock);



/*--------------*/

/*     data     */
@@ -601,16 +600,13 @@ static int iowarrior_open(struct inode *inode, struct file *file) 
		return -ENODEV;

	}



	mutex_lock(&iowarrior_open_disc_lock);

	dev = usb_get_intfdata(interface);

	if (!dev) {

		mutex_unlock(&iowarrior_open_disc_lock);

		mutex_unlock(&iowarrior_mutex);

		return -ENODEV;

	}



	mutex_lock(&dev->mutex);

	mutex_unlock(&iowarrior_open_disc_lock);



	/* Only one process can open each device, no sharing. */

	if (dev->opened) {
@@ -842,7 +838,6 @@ static int iowarrior_probe(struct usb_interface *interface, 
	if (retval) {

		/* something prevented us from registering this driver */

		dev_err(&interface->dev, "Not able to get a minor for this device.\n");

		usb_set_intfdata(interface, NULL);

		goto error;

	}
@@ -866,16 +861,8 @@ error: 
 */

static void iowarrior_disconnect(struct usb_interface *interface)

{

	struct iowarrior *dev;

	int minor;



	dev = usb_get_intfdata(interface);

	mutex_lock(&iowarrior_open_disc_lock);

	usb_set_intfdata(interface, NULL);



	minor = dev->minor;

	mutex_unlock(&iowarrior_open_disc_lock);

	/* give back our minor - this will call close() locks need to be dropped at this point*/

	struct iowarrior *dev = usb_get_intfdata(interface);

	int minor = dev->minor;



	usb_deregister_dev(interface, &iowarrior_class);

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