Subject: Re: 2.6.25-rc9: Reported regressions from 2.6.24

From: Patrick McHardy <[email-masked]>
Date: Mon, 14 Apr 2008 10:50:04 +0200

Pavel Emelyanov wrote:
> Patrick McHardy wrote:
>> Rafael J. Wysocki wrote:
>>> This message contains a list of some regressions from 2.6.24, for which there
>>> are no fixes in the mainline I know of.  If any of them have been fixed already,
>>> please let me know.
>>>
>>>
>>> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=10323
>>> Subject		: panic using bridging on linus kernel 2.6.25-rc6
>>> Submitter	: Andy Gospodarek <[email-masked]>
>>> Date		: 2008-03-25 11:40 (20 days old)
>> This looks like another network-namespace regression.
>> icmp_send() does:
>>
>>         net = rt->u.dst.dev->nd_net;
>>
>> The bridge netfilter code attaches a fake dst_entry to the
>> skb which has dev == NULL when passing it to IPv4 netfilter.
>>
>> Pavel, do you have a better ideas for fixing this than
>> instantiating a dst_entry in br_netfilter.c for every
>> device (or at least for every namespace)?
> 
> Hm... Why not make this dst entry point to looback device? This would
> allow us to make the dst entry per-namespace and instantiate it with
> the ns's lo.

I thought of that myself, but that will result in MTU problems.
The current way is not ideal either (hardcoded MTU of 1500 for
the fake net_device), but that at least works in normal bridge
setups.