netdev - Re: ipv6 neighbour code keeps interfaces held

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Date:	Thu, 11 Sep 2008 01:57:33 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: ipv6 neighbour code keeps interfaces held

On Wed, 2008-09-10 at 16:40 -0700, David Miller wrote:

> This is yet another side effect of how ipv6 handles ICMP routes
> seperately from "real" ipv6 routes.

I have no idea :) I just had never seen this on a wired interface and
wanted to see if it was mac80211's fault although I couldn't see how it
could have been.

> Anyways, what happens is that when a device goes down a notifier
> goes out, and in IPV6's case it has a notifier registered in
> net/ipv6/addrconf.c that ends up calling rt6_ifdown() on
> the device.
> 
> This is supposed to purge routes from the tree so that the device
> references can be dropped (eventually).
> 
> This is done in ipv6 by fib6_clean_all() but that only handles
> normal routes.  The seperate ICMP6 routes are not purged properly
> in this situation.

And then they time out after 30 seconds? I see the message exactly three
times and then it gets removed.

> Here is a quick patch that might resolve this specific situation.
> Let me know how it works for you:

I'll add it to my tree, but I cannot reproduce the issue at will. It
just happens occasionally when I'm developing.

johannes

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