Commit 341487a8 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

USB: remove use of the bus rwsem, as it doesn't really protect anything. 



The driver core stopped using the rwsem a long time ago, yet the USB
core still grabbed the lock, thinking it protected something.  This
patch removes that useless use.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: David Brownell <david-b@pacbell.net>
Cc: linux-usb-devel <linux-usb-devel@lists.sourceforge.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent b7bb125d

drivers/usb/core/devices.c

+0 −2
Original line number Diff line number Diff line
@@ -246,7 +246,6 @@ static char *usb_dump_interface_descriptor(char *start, char *end, 


	if (start > end)

		return start;

	down_read(&usb_bus_type.subsys.rwsem);

	if (iface) {

		driver_name = (iface->dev.driver

				? iface->dev.driver->name
@@ -263,7 +262,6 @@ static char *usb_dump_interface_descriptor(char *start, char *end, 
			 desc->bInterfaceSubClass,

			 desc->bInterfaceProtocol,

			 driver_name);

	up_read(&usb_bus_type.subsys.rwsem);

	return start;

}

drivers/usb/core/devio.c

+0 −13
Original line number Diff line number Diff line
@@ -421,14 +421,11 @@ static int claimintf(struct dev_state *ps, unsigned int ifnum) 
	if (test_bit(ifnum, &ps->ifclaimed))

		return 0;



	/* lock against other changes to driver bindings */

	down_write(&usb_bus_type.subsys.rwsem);

	intf = usb_ifnum_to_if(dev, ifnum);

	if (!intf)

		err = -ENOENT;

	else

		err = usb_driver_claim_interface(&usbfs_driver, intf, ps);

	up_write(&usb_bus_type.subsys.rwsem);

	if (err == 0)

		set_bit(ifnum, &ps->ifclaimed);

	return err;
@@ -444,8 +441,6 @@ static int releaseintf(struct dev_state *ps, unsigned int ifnum) 
	if (ifnum >= 8*sizeof(ps->ifclaimed))

		return err;

	dev = ps->dev;

	/* lock against other changes to driver bindings */

	down_write(&usb_bus_type.subsys.rwsem);

	intf = usb_ifnum_to_if(dev, ifnum);

	if (!intf)

		err = -ENOENT;
@@ -453,7 +448,6 @@ static int releaseintf(struct dev_state *ps, unsigned int ifnum) 
		usb_driver_release_interface(&usbfs_driver, intf);

		err = 0;

	}

	up_write(&usb_bus_type.subsys.rwsem);

	return err;

}
@@ -813,7 +807,6 @@ static int proc_getdriver(struct dev_state *ps, void __user *arg) 


	if (copy_from_user(&gd, arg, sizeof(gd)))

		return -EFAULT;

	down_read(&usb_bus_type.subsys.rwsem);

	intf = usb_ifnum_to_if(ps->dev, gd.interface);

	if (!intf || !intf->dev.driver)

		ret = -ENODATA;
@@ -822,7 +815,6 @@ static int proc_getdriver(struct dev_state *ps, void __user *arg) 
				sizeof(gd.driver));

		ret = (copy_to_user(arg, &gd, sizeof(gd)) ? -EFAULT : 0);

	}

	up_read(&usb_bus_type.subsys.rwsem);

	return ret;

}
@@ -1351,15 +1343,12 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) 


	/* disconnect kernel driver from interface */

	case USBDEVFS_DISCONNECT:



		down_write(&usb_bus_type.subsys.rwsem);

		if (intf->dev.driver) {

			driver = to_usb_driver(intf->dev.driver);

			dev_dbg (&intf->dev, "disconnect by usbfs\n");

			usb_driver_release_interface(driver, intf);

		} else

			retval = -ENODATA;

		up_write(&usb_bus_type.subsys.rwsem);

		break;



	/* let kernel drivers try to (re)bind to the interface */
@@ -1371,7 +1360,6 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) 


	/* talk directly to the interface's driver */

	default:

		down_read(&usb_bus_type.subsys.rwsem);

		if (intf->dev.driver)

			driver = to_usb_driver(intf->dev.driver);

		if (driver == NULL || driver->ioctl == NULL) {
@@ -1381,7 +1369,6 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) 
			if (retval == -ENOIOCTLCMD)

				retval = -ENOTTY;

		}

		up_read(&usb_bus_type.subsys.rwsem);

	}



	/* cleanup and return */

drivers/usb/core/driver.c

+6 −6
Original line number Diff line number Diff line
@@ -287,9 +287,9 @@ static int usb_unbind_interface(struct device *dev) 
 * way to bind to an interface is to return the private data from

 * the driver's probe() method.

 *

 * Callers must own the device lock and the driver model's usb_bus_type.subsys

 * writelock.  So driver probe() entries don't need extra locking,

 * but other call contexts may need to explicitly claim those locks.

 * Callers must own the device lock, so driver probe() entries don't need

 * extra locking, but other call contexts may need to explicitly claim that

 * lock.

 */

int usb_driver_claim_interface(struct usb_driver *driver,

				struct usb_interface *iface, void* priv)
@@ -330,9 +330,9 @@ EXPORT_SYMBOL(usb_driver_claim_interface); 
 * also causes the driver disconnect() method to be called.

 *

 * This call is synchronous, and may not be used in an interrupt context.

 * Callers must own the device lock and the driver model's usb_bus_type.subsys

 * writelock.  So driver disconnect() entries don't need extra locking,

 * but other call contexts may need to explicitly claim those locks.

 * Callers must own the device lock, so driver disconnect() entries don't

 * need extra locking, but other call contexts may need to explicitly claim

 * that lock.

 */

void usb_driver_release_interface(struct usb_driver *driver,

					struct usb_interface *iface)

drivers/usb/core/message.c

+1 −1
Original line number Diff line number Diff line
@@ -1349,7 +1349,7 @@ static void release_interface(struct device *dev) 
 *

 * This call is synchronous. The calling context must be able to sleep,

 * must own the device lock, and must not hold the driver model's USB

 * bus rwsem; usb device driver probe() methods cannot use this routine.

 * bus mutex; usb device driver probe() methods cannot use this routine.

 *

 * Returns zero on success, or else the status code returned by the

 * underlying call that failed.  On successful completion, each interface

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