netdev - Re: [RFC patch net-next-2.6] net: allow multiple rx

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Date:	Thu, 30 Jun 2011 19:22:57 +0200
From:	Jiri Pirko <jpirko@...hat.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, kaber@...sh.net,
	fubar@...ibm.com, eric.dumazet@...il.com,
	nicolas.2p.debian@...il.com, andy@...yhouse.net
Subject: Re: [RFC patch net-next-2.6] net: allow multiple rx_handler
 registration

Thu, Jun 30, 2011 at 06:27:12PM CEST, shemminger@...tta.com wrote:
>On Thu, 30 Jun 2011 17:16:49 +0200
>Jiri Pirko <jpirko@...hat.com> wrote:
>
>> For some net topos it is necessary to have multiple "soft-net-devices"
>> hooked on one netdev. For example very common is to have
>> eth<->(br+vlan). Vlan is not using rh_handler (yet) but also for example
>> macvlan would be useful to have hooked on same netdev as br.
>> 
>> This patch introduces rx_handler list. size struct net_device stays
>> intact. Measured performance regression on eth-br topo is ~1% (on received
>> pkts generated by pktgen) and on eth-bond topo it is ~0.25%
>> 
>> On br I think that the performance can be brought back maybe by using per-cpu
>> variables to store port in rx_path (I must check this)
>> 
>> Please comment.
>> 
>> Signed-off-by: Jiri Pirko <jpirko@...hat.com>
>
>I am ok with the infrastructure, but why should Vlan use rh_handle.

Well why it shoudln't. It would fit into what rx_handler is here for - the
code would be more unified. Also net_device struct would lose struct
vlan_group __rcu *vlgrp pointer (and reducing net_device size is always
good thing).

>It is wrong to allow macvlan and bridge to share same device.
>Right now the code blocks users from doing lots of stupid things.

Right, this is since rx_handler was introduced. Before that all these
stupid configs were allowed. It's possible easily to forbid unwanted
configs by checking priv flags.

>
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