On Thu, Jan 02, 2014 at 01:48:46PM +0800, chenweilong wrote:

On 2013/12/31 11:57, Hannes Frederic Sowa wrote:

quoted

On Wed, Jun 19, 2013 at 11:05:32PM -0700, David Miller wrote:

quoted

From: Gao feng <redacted>
Date: Sun, 16 Jun 2013 11:14:30 +0800

quoted

If we disable all of the net interfaces, and enable
un-lo interface before lo interface, we already allocated
the addrconf dst in ipv6_add_addr. So we shouldn't allocate
it again when we enable lo interface.

Otherwise the message below will be triggered.
unregister_netdevice: waiting for sit1 to become free. Usage count = 1

This problem is introduced by commit 25fb6ca4ed9cad72f14f61629b68dc03c0d9713f
"net IPv6 : Fix broken IPv6 routing table after loopback down-up"

Signed-off-by: Gao feng <redacted>

This is the second such regression added by that commit :-/

Applied and queue up for -stable, thanks.

Hmm, and this change also has a regression and breaks the original fix. :/

https://bugzilla.kernel.org/show_bug.cgi?id=67951

I tried to track it down but it seems pretty complicated. Maybe we have to
special-case the take-down of the loopback device.

When I did the tests,If 'ifconfig lo down',all IPv6 connection broken,
but IPv4 connection were still OK.

Is it designed like that or a bug?

This seems to solve the loopback up/down problem, but there are still
some issues with up/down of interfaces and routing table interactions.

We enable routes over interfaces when interface is actually down and
kick manually specified on-link routes when we actually should try to
keep them and just disable them.

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6c16345..61d752a 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -2629,8 +2629,10 @@ static void init_loopback(struct net_device *dev)
 			if (sp_ifa->flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE))
 				continue;
 
-			if (sp_ifa->rt)
+			if (sp_ifa->rt) {
+				ip6_ins_rt(sp_ifa->rt);
 				continue;
+			}
 
 			sp_rt = addrconf_dst_alloc(idev, &sp_ifa->addr, false);