netdev - Re: [PATCH v2 net-next 2/4] net: dev: add batching to net

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Date:	Sun, 7 Feb 2016 12:09:22 +0200 (EET)
From:	Julian Anastasov <ja@....bg>
To:	Salam Noureddine <noureddine@...sta.com>
cc:	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jiri Pirko <jiri@...lanox.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 net-next 2/4] net: dev: add batching to net_device
 notifiers


	Hello,

On Sat, 6 Feb 2016, Salam Noureddine wrote:

> On Sat, Feb 6, 2016 at 10:58 AM, Julian Anastasov <ja@....bg> wrote:

> >> +     /* 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.

	ok. May be another safe option is to call it just before
NETDEV_UNREGISTER, so that if rollback_registered_many is called
recursively we will have single NETDEV_UNREGISTER_BATCH call.
Same should work for NETDEV_DOWN_BATCH in dev_close_many. But
these are small optimizations, so it is up to you to decide.

Regards

--
Julian Anastasov <ja@....bg>