Roman, Pat:
Here is a fix for driver_detach(). It's a little ugly because it avoids
using the klist iterator, but there's no way around it -- the iterator
simply can't be made to work here. Not only does it prevent
device_release_driver() from calling klist_remove(), but also it prevents
doing get_device() while holding the klist spinlock.
With this patch in place, the code in usb_driver_release_interface()
doesn't really need to be changed. However I think it should be. As it
is now, it relies on internal knowledge of how the driver-model core
works, namely that dev->knode_driver is released _before_ drv->remove()
gets called. They could easily go the other way around.
What do you think?
Alan Stern
Index: driver-2.6/drivers/base/dd.c
===================================================================
--- driver-2.6.orig/drivers/base/dd.c
+++ driver-2.6/drivers/base/dd.c
@@ -184,37 +184,37 @@ void driver_attach(struct device_driver
* @dev: device.
*
* Manually detach device from driver.
- * Note that this is called without incrementing the bus
- * reference count nor taking the bus's rwsem. Be sure that
- * those are accounted for before calling this function.
+ *
+ * __device_release_driver() must be called with @dev->sem held.
*/
-void device_release_driver(struct device * dev)
+static void __device_release_driver(struct device * dev)
{
struct device_driver * drv;
- down(&dev->sem);
- if (dev->driver) {
- drv = dev->driver;
+ drv = dev->driver;
+ if (drv) {
+ get_driver(drv);
sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver");
- klist_del(&dev->knode_driver);
+ klist_remove(&dev->knode_driver);
device_detach_shutdown(dev);
if (drv->remove)
drv->remove(dev);
dev->driver = NULL;
+ put_driver(drv);
}
- up(&dev->sem);
}
-
-static int __remove_driver(struct device * dev, void * unused)
+void device_release_driver(struct device * dev)
{
- device_release_driver(dev);
- return 0;
+ down(&dev->sem);
+ __device_release_driver(dev);
+ up(&dev->sem);
}
+
/**
* driver_detach - detach driver from all devices it controls.
* @drv: driver.
@@ -222,7 +222,25 @@ static int __remove_driver(struct device
void driver_detach(struct device_driver * drv)
{
- driver_for_each_device(drv, NULL, NULL, __remove_driver);
+ struct device * dev;
+
+ for (;;) {
+ spin_lock_irq(&drv->klist_devices.k_lock);
+ if (list_empty(&drv->klist_devices.k_list)) {
+ spin_unlock_irq(&drv->klist_devices.k_lock);
+ break;
+ }
+ dev = list_entry(drv->klist_devices.k_list.prev,
+ struct device, knode_driver.n_node);
+ get_device(dev);
+ spin_unlock_irq(&drv->klist_devices.k_lock);
+
+ down(&dev->sem);
+ if (dev->driver == drv)
+ __device_release_driver(dev);
+ up(&dev->sem);
+ put_device(dev);
+ }
}
EXPORT_SYMBOL_GPL(device_bind_driver);
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