On Sat, Jun 23, 2012 at 4:45 PM, Bjørn Mork <bjorn@xxxxxxx> wrote: > usbnet_disconnect() cannot continue to the point where it frees the > netdev before wdm_open/wdm_close has completed, because it waits for > qmi_wwan_unbind which waits for wdm_disconnect. And wdm_disconnect > takes the both read and write mutexes. Thanks for your explanation. I see, and your patch is correct, but it might not be generic enough. So driver_info->unbind will sync with .open/.close of the subdriver, just like unregister_netdev will sync with .open/.close of usbnet interface. IMO, the general solution is to keep intfdata's lifetime after ->unbind, which can guarantee that intfdata can be accessed safely in .open/.close of usbnet interface and the other subdrivers' device. Suppose there will be another usbnet driver which has its own subdriver too, the same trick of checking need to be added again if not taking the general way of simply removing 'usb_set_intfdata(intf, NULL);' in usbnet_disconnect. 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
