Commit 9496c745 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman

[PATCH] USB: correct error handling in usb_driver_claim_interface()

this function races with itself, doesn't return errors and races with
releasing interfaces. This patch fixes it by changing the function
prototype, introducing locking and having a correct order in
releasing interfaces.

  - API change to check errors in usb_driver_claim_interface and
    fix a race condition between releasing and reclaiming an interface
parent 09a12dff
......@@ -261,24 +261,27 @@ usb_epnum_to_ep_desc(struct usb_device *dev, unsigned epnum)
*
* Few drivers should need to use this routine, since the most natural
* way to bind to an interface is to return the private data from
* the driver's probe() method. Any driver that does use this must
* first be sure that no other driver has claimed the interface, by
* checking with usb_interface_claimed().
* the driver's probe() method.
*/
void usb_driver_claim_interface(struct usb_driver *driver, struct usb_interface *iface, void* priv)
int usb_driver_claim_interface(struct usb_driver *driver, struct usb_interface *iface, void* priv)
{
if (!iface || !driver)
return;
return -EINVAL;
// FIXME change API to report an error in this case
if (iface->driver)
err ("%s driver booted %s off interface %p",
driver->name, iface->driver->name, iface);
else
lock_kernel();
if (iface->driver) {
unlock_kernel();
err ("%s driver booted %s off interface %p",
driver->name, iface->driver->name, iface);
return -EBUSY;
} else {
dbg("%s driver claimed interface %p", driver->name, iface);
}
iface->driver = driver;
usb_set_intfdata(iface, priv);
unlock_kernel();
return 0;
}
/**
......@@ -324,11 +327,11 @@ void usb_driver_release_interface(struct usb_driver *driver, struct usb_interfac
if (iface->driver && iface->driver != driver)
return;
iface->driver = NULL;
usb_set_intfdata(iface, NULL);
usb_set_interface(interface_to_usbdev(iface),
iface->altsetting[0].desc.bInterfaceNumber,
0);
usb_set_intfdata(iface, NULL);
iface->driver = NULL;
}
/**
......
......@@ -290,7 +290,7 @@ extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
extern int usb_get_current_frame_number (struct usb_device *usb_dev);
/* used these for multi-interface device registration */
extern void usb_driver_claim_interface(struct usb_driver *driver,
extern int usb_driver_claim_interface(struct usb_driver *driver,
struct usb_interface *iface, void* priv);
extern int usb_interface_claimed(struct usb_interface *iface);
extern void usb_driver_release_interface(struct usb_driver *driver,
......
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