On Sat, Feb 6, 2016 at 10:58 AM, Julian Anastasov <[email protected]> wrote:
>
> I now see that we should split the loop
> here, so that NETDEV_DOWN_BATCH is called only once per net:
>
> bool down = false;
>
> for_each_netdev(net, dev) {
> if (dev == last)
> break;
>
> if (dev->flags & IFF_UP) {
> call_netdevice_notifier(nb, NETDEV_GOING_DOWN,
> dev);
> call_netdevice_notifier(nb, NETDEV_DOWN, dev);
> down = true;
> }
> }
>
> rt_cache_flush and arp_ifdown_all will be called
> on NETDEV_UNREGISTER_BATCH, so use 'down' flag:
>
> if (down)
> call_netdevice_notifier(nb, NETDEV_DOWN_BATCH,
> net->loopback_dev);
> for_each_netdev(net, dev) {
> if (dev == last)
> goto outroll;
> call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
> }
> call_netdevice_notifier(nb, NETDEV_UNREGISTER_BATCH,
> net->loopback_dev);
>
>
>> }
>> call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
>> }
>> + call_netdevice_notifier(nb, NETDEV_UNREGISTER_BATCH,
>> + net->loopback_dev);
>> }
>>
>> outroll:
>> + call_netdevice_notifier(nb, NETDEV_UNREGISTER_BATCH, last);
>> raw_notifier_chain_unregister(&netdev_chain, nb);
>> goto unlock;
>> }
I am not sure we need to worry too much about optimizing the failure
code path to justify splitting into two loops.
>> static void rollback_registered_many(struct list_head *head)
>> {
>> list_for_each_entry(dev, head, unreg_list) {
>> - struct sk_buff *skb = NULL;
>> -
>> /* Shutdown queueing discipline. */
>> dev_shutdown(dev);
>>
>> @@ -6475,6 +6497,20 @@ static void rollback_registered_many(struct list_head
>> *head)
>> this device. They should clean all the things.
>> */
>> call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
>> + }
>> +
>> + /* call batch notifiers which act on net namespaces */
>> + list_for_each_entry(dev, head, unreg_list) {
>> + net_add_event_list(&net_head, dev_net(dev));
>
> Looks like we can move the above net_add_event_list with
> the comment into the previous loop after NETDEV_UNREGISTER,
> we will save some cycles.
>
I didn't move it into the previous loop because the NETDEV_UNREGISTER
notifier can
end up calling rollback_registered_many (for example the vlan driver
unregistering
all vlans on top of a device) in which case we would be using the
event_list in the net
namespace.
> Julian Anastasov <[email protected]>
Thanks,
Salam
