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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: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Greg Kroah-Hartman 2007-04-09 11:52:31 -04:00
parent b7bb125dc3
commit 341487a837
4 changed files with 7 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/usb/core/devices.c
View File

@ -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;
}

13
drivers/usb/core/devio.c
View File

@ -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 */

12
drivers/usb/core/driver.c
View File

@ -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)

2
drivers/usb/core/message.c
View File

@ -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