Hi, On Tue, Jun 5, 2012 at 5:18 PM, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, Jun 05, 2012 at 04:59:07PM +0800, Ming Lei wrote: >> Firstly, .shutdown callback may touch a uninitialized hardware >> if dev->driver is set and .probe is not completed. > > When would that ever happen? It may happen when someone plugs a device, then run 'shutdown' immediately. > >> Secondly, device_shutdown() may dereference a null pointer to cause >> oops when dev->driver is cleared after it is checked in device_shutdown(). > > Again, when would that happen? A new device/driver being added to the > system as it is being shutdown? It is usually that someone presses 'power off' button and unplugs its usb devices or pci/e devices, maybe together with a new plug. In such case, the oops may be triggered. > > Has anyone ever hit that before? Looks someone has reported it, I also can trigger it with some delay added in device_shutdown. > > Is this really needed? In case that it is triggered, oops will prevent system from being shutdown, and it should be a big problem. IMO, we can avoid it without much change and side effect, so looks worthy the change. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
