On Sat, Jun 23, 2012 at 12:18 AM, Bjørn Mork <bjorn@xxxxxxx> wrote: > Ming Lei <tom.leiming@xxxxxxxxx> writes: > Yes, intfdata is per interface, but in the case of cdc_ether (and > probably other similar minidrivers) there are two interfaces pointing to > the *same* usbnet private data. Yes, the priv pointers of both interface points to the usbnet instance, but the same pointer is stored into two places. > > What about the situation where disconnect is called simultaneously for > both interfaces? Or can't that happen? If it can, then we'll do It can't happen because both parent lock and its lock need to be held in hotplug situation or unbind situation. > > driver->disconnect(intf1) driver->disconnect(intf2) > dev = usb_get_intfdata(intf1) dev = usb_get_intfdata(intf2) > dev->driver_info->unbind() dev->driver_info->unbind() > net = dev->net net = dev->net > free_netdev(net) free_netdev(dev->net) > > where "dev" and "net" will be pointing to the same private data and > netdevice. Suppose driver->disconnect(intf1) is called first, .ubind() inside .disconnect will clear intfdata of another interface(intf2) and call usb_driver_release_interface(intf2), which will cause .disconnect(intf2) called, but it will return immediately. > > I assume that is what the code above is trying to protect against. But I don't see the protection in the code, :-) > I could be wrong. That has happened before, believe it or not :-) Could you provide a link or commit about it? 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
