On 07/30/2018, 10:18 AM, Xiao Liang wrote: > On 07/29/2018 11:30 PM, David Miller wrote: >> From: Xiao Liang <xili...@redhat.com> >> Date: Fri, 27 Jul 2018 17:56:08 +0800 >> >>> @@ -1330,6 +1331,11 @@ static struct net_device >>> *xennet_create_dev(struct xenbus_device *dev) >>> netif_carrier_off(netdev); >>> xenbus_switch_state(dev, XenbusStateInitialising); >>> + wait_event(module_load_q, >>> + xenbus_read_driver_state(dev->otherend) != >>> + XenbusStateClosed && >>> + xenbus_read_driver_state(dev->otherend) != >>> + XenbusStateUnknown); >>> return netdev; >>> exit: >> What performs the wakeups that will trigger for this sleep site? > In my understanding, backend leaving closed/unknow state can trigger the > wakeups. I mean to make sure both sides are ready for creating connection.
While backporting this to 4.12, I was surprised by the commit the same as Boris and David. So I assume the explanation is that wake_up_all of module_unload_q in netback_changed wakes also all the processes waiting on module_load_q? If so, what makes sure that module_unload_q is queued and the process is the same as for module_load_q? To me, it looks rather error-prone. Unless it is erroneous now, at least for future changes. Wouldn't it make sense to wake up module_load_q along with module_unload_q in netback_changed? Or drop module_load_q completely and use only module_unload_q (i.e. in xennet_create_dev too)? thanks, -- js suse labs _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
