On 08/24/2018 07:26 AM, Juergen Gross wrote: > On 24/08/18 13:12, Jiri Slaby wrote: >> 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? > How could it? Either the thread is waiting on module_unload_q _or_ on > module_load_q. It can't wait on two queues at the same time. > >> 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)? > To me this looks just wrong. A thread waiting on module_load_q won't be > woken up again. > > I'd drop module_load_q in favor of module_unload_q.
Yes, use single queue, but rename it to something more neutral. module_wq? -boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
