ipv6: don't call addrconf_dst_alloc again when enable lo

[ Upstream commit a881ae1f625c599b460cc8f8a7fcb1c438f699ad ]

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 <gaofeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d603caa..a7fe50f 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2434,6 +2434,9 @@ static void init_loopback(struct net_device *dev)
                        if (sp_ifa->flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE))
                                continue;
 
+                       if (sp_ifa->rt)
+                               continue;
+
                        sp_rt = addrconf_dst_alloc(idev, &sp_ifa->addr, 0);
 
                        /* Failure cases are ignored */