Ming Lei <tom.leiming@xxxxxxxxx> writes: > 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. OK, then it can probably go away. But then again it doesn't do any harm for any other minidriver. qmi_wwan is special because of the cooperation with cdc_wdm. >> 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. Yes, if that's the only possible call sequence then I agree that removing the call won't be a problem. But I don't see much gain either. And it has been there since the beginning of git history, if that counts for anything around here. >> I assume that is what the code above is trying to protect against. But > > I don't see the protection in the code, :-) I am trying my best to be positive :-) Bjørn -- 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
