On Tue, 26 Apr 2005, Roman Kagan wrote: > On Mon, Apr 25, 2005 at 04:01:07PM -0400, Alan Stern wrote: > > I think usb_driver_claim_interface is correct as it stands. It was a > > mistake to leave out from usb_driver_release_interface originally the line > > setting iface->condition to USB_INTERFACE_UNBINDING. > > But it would be asymmetric then.
In what sense? You mean because we don't also protect against a driver calling usb_driver_claim_interface from within that interface's probe? We don't need to check for that, do we? > FWIW my personal preference would be > to get rid of usb_interface.condition altogether, and always use the > driver base facilities to deduce the current interface bound state. > Otherwise maintaining a private field in sync with what the driver base > thinks is always error prone. There are other reasons for keeping usb_interface.condition. For one thing, the driver-model data doesn't tell when a bind or unbind is in progress. That information is used elsewhere in usbcore. > > The _driver_ shouldn't check. The check should be part of the > > driver-model core in __driver_attach, at the place where it checks whether > > the device is already bound to a driver. In fact, this check can subsume > > that one, since the klist_node will always be attached whenever the device > > is bound. > > Indeed. I guess all checks for whether the device is associated with > a driver ought to be changed from !dev->driver to > klist_node_attached(&dev->knode_driver). I'm not so sure about that. You wouldn't want to dereference dev->driver after doing only the klist_node_attached check! Unfortunately there are several spots where a device can be bound to a driver, and the code generally doesn't check for errors. This makes it difficult to check klist_node_attached at each spot. The best solution would be always to have device_release_driver wait for the klist_node's completion before releasing the semaphore. But there's no simple way to do that, given how driver_detach works. Alan Stern ------------------------------------------------------- SF.Net email is sponsored by: Tell us your software development plans! Take this survey and enter to win a one-year sub to SourceForge.net Plus IDC's 2005 look-ahead and a copy of this survey Click here to start! http://www.idcswdc.com/cgi-bin/survey?id=105hix _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
