If an entry is being deleted because it has only one reference, 
we immediately delete it and blindly register the rcu handler for it,
This results in oops by double freeing that object.

This patch fixes it by consolidating the code paths for the deletion;
let its rcu handler delete the object if it has no more reference.

Bug was found by Mitsuru Chinen <mitch@linux.vnet.ibm.com>
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix following sparse warnings:
| net/ipv6/addrlabel.c:172:25: warning: symbol 'ip6addrlbl_alloc' was not declared. Should it be static?
| net/ipv6/addrlabel.c:219:5: warning: symbol '__ip6addrlbl_add' was not declared. Should it be static?
| net/ipv6/addrlabel.c:260:5: warning: symbol 'ip6addrlbl_add' was not declared. Should it be static?
| net/ipv6/addrlabel.c:285:5: warning: symbol '__ip6addrlbl_del' was not declared. Should it be static?
| net/ipv6/addrlabel.c:311:5: warning: symbol 'ip6addrlbl_del' was not declared. Should it be static?
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

After this patch none of the netlink callback support anything
except the initial network namespace but the rtnetlink infrastructure
now handles multiple network namespaces.

Changes from v2:
- IPv6 addrlabel processing

Changes from v1:
- no need for special rtnl_unlock handling
- fixed IPv6 ndisc
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Before I can enable rtnetlink to work in all network namespaces I need
to be certain that something won't break.  So this patch deliberately
disables all of the rtnletlink methods in everything except the
initial network namespace.  After the methods have been audited this
extra check can be disabled.

Changes from v1:
- added IPv6 addrlabel protection
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Policy table is implemented as an RCU linear list since we do not expect
large list nor frequent updates.
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>