Subject: Re: [PATCH 6/17 net-2.6.26] [NETNS]: Default arp parameters lookup.

From: Daniel Lezcano <[email-masked]>
Date: Tue, 19 Feb 2008 11:22:35 +0100

Denis V. Lunev wrote:
> On Tue, 2008-02-19 at 10:51 +0100, Daniel Lezcano wrote:
>> Denis V. Lunev wrote:
>>> On Tue, 2008-02-19 at 10:14 +0100, Daniel Lezcano wrote:
>>>> Denis V. Lunev wrote:
>>>>> Default ARP parameters should be findable regardless of the context.
>>>>> Required to make inetdev_event working.
>>>>>
>>>>> Signed-off-by: Denis V. Lunev <[email-masked]>
>>>>> ---
>>>>>  net/core/neighbour.c |    4 +---
>>>>>  1 files changed, 1 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
>>>>> index c895ad4..45ed620 100644
>>>>> --- a/net/core/neighbour.c
>>>>> +++ b/net/core/neighbour.c
>>>>> @@ -1275,9 +1275,7 @@ static inline struct neigh_parms *lookup_neigh_params(struct neigh_table *tbl,
>>>>>  	struct neigh_parms *p;
>>>>>
>>>>>  	for (p = &tbl->parms; p; p = p->next) {
>>>>> -		if (p->net != net)
>>>>> -			continue;
>>>>> -		if ((p->dev && p->dev->ifindex == ifindex) ||
>>>>> +		if ((p->dev && p->dev->ifindex == ifindex && p->net == net) ||
>>>>>  		    (!p->dev && !ifindex))
>>>>>  			return p;
>>>>>  	}
>>>> If the values are:
>>>> 	p->dev == NULL
>>>> 	ifindex == 0
>>>> 	p->net != net
>>>>
>>>> The parms should not be taken into account and the looping must 
>>>> continue. But with this modification it is not the case, if we specify 
>>>> parms ifindex == 0, the first parms with the dev field set to NULL will 
>>>> be taken belonging or not to the right net.
>>> They should be taken. In the other case inetdev_event will fail for sure
>>> in the middle. You could check.
>>>
>>> These are ARP defaults and I do not see a problem for now to get them.
>> Because there is a parms default per namespace. So several instances of 
>> them per nd table. That was the initial approach with Eric's patchset.
>>
> 
> These changes are not in mainstream and I do not want to touch ARP as
> this is not a simple thing. In reality ARP will be needed only when
> we'll have a real device inside a namespace.
> 
> Right now I prefer to have minimal set of working changes to finish IP
> and upper layers.

core/neighbour.c is a common part between several protocols, especially 
ipv4 and ipv6. If you modify this function just to fit your need in the 
arp that will block me for ipv6 until you make parms default per 
namespace. So please, find another way to do that, perhaps just add a 
helper function.

I suggest you do parms default per namespace first, it is quite small 
and easy :)

Just let me the time to send the copy-parms-default function.

Is it ok ?

   -- Daniel

  -- Daniel