On Mon, 5 Jan 2004, Alan Stern wrote:
> The best way to prevent that from becoming a problem is for
> usb_disconnect() to insure the hub isn't on the event list to begin with.
> And the best way to insure _that_ is to unbind the hub driver.
In fact, this isn't such a big change as one might think. It doesn't even
require any special code, just a slight reorganization of
usb_disconnect(). Right now the routine does (in outline):
dev->state = NOTATTACHED;
down(&dev->serialize);
for each port
usb_disconnect(&dev->children[port]);
usb_disable_device(dev); // Does the unbind
free devnum bit
usbfs_remove_device(dev);
up(&dev->serialize);
device_unregister(&dev->dev);
The necessary changes are fairly small. Basically it changes the process
from a bottom-up to a pure top-down approach.
down(&dev->serialize);
dev->state = NOTATTACHED;
usb_disable_device(dev); // Does the unbind
usbfs_remove_device(dev);
free devnum bit
for each child of dev->dev
usb_disconnect(to_usbdev(child));
up(&dev->serialize);
device_unregister(&dev->dev);
Another advantage is that this way, when we reach the loop to handle the
children the only driver-model children of the device are usb_devices. If
we add a parent_port field to struct usb_device then the children[] array
wouldn't be needed at all!
Alan Stern
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