netdev - Re: Possible networking regression in 3.6.0

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Date:	Wed, 3 Oct 2012 23:57:08 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	David Miller <davem@...emloft.net>
cc:	eric.dumazet@...il.com, chris2553@...glemail.com,
	netdev@...r.kernel.org, gpiez@....de, davej@...hat.com
Subject: Re: Possible networking regression in 3.6.0


	Hello,

On Tue, 2 Oct 2012, David Miller wrote:

> From: Julian Anastasov <ja@....bg>
> Date: Wed, 3 Oct 2012 02:24:53 +0300 (EEST)
> 
> > 	Can it be a problem related to fib_info reuse
> > from different routes. For example, when local IP address
> > is created for subnet we have:
> > 
> > broadcast 192.168.0.255 dev DEV  proto kernel  scope link  src 192.168.0.1
> > 192.168.0.0/24 dev DEV  proto kernel  scope link  src 192.168.0.1
> > local 192.168.0.1 dev DEV  proto kernel  scope host  src 192.168.0.1
> > 
> > 	The "dev DEV  proto kernel  scope link  src 192.168.0.1" is
> > a reused fib_info structure where we put cached routes.
> > The result can be same fib_info for 192.168.0.255 and
> > 192.168.0.0/24. RTN_BROADCAST is cached only for input
> > routes. Incoming broadcast to 192.168.0.255 can be cached
> > and can cause problems for traffic forwarded to 192.168.0.0/24.
> > So, this patch should solve the problem because it
> > separates the broadcast from unicast traffic.
> 
> Now I understand the problem.
> 
> I think the way to fix this is to add cfg->fc_type as another
> thing that fib_info objects are key'd by.
> 
> I think it also would fix your obscure output multicast case too.

	Agreed. I don't see problem with this idea.
It will avoid confusions with rt_type.

Regards

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