In preparation for using the IPv4 and IPv6 neighbour tables in my mpls
code this patchset factors out ___neigh_lookup_noref from
__ipv4_neigh_lookup_noref, __ipv6_lookup_noref and neigh_lookup.
Allowing the lookup logic to be shared between the different
implementations.  At what appears to be no cost. (Aka the same assembly
is generated for ip6_finish_output2 and ip_finish_output2).

After that I add a simple function that takes an address family and an
address consults the neighbour table and sends the packet to the
appropriate location.  The address family argument decoupls callers
of neigh_xmit from the addresses families the packets are sent over.
(Aka The ipv6 module can be loaded after mpls and a previously
configured ipv6 next hop will start working).

The refactoring in ___neigh_lookup_noref may be a bit overkill but it
feels like the right thing to do.  Especially since the same code is
generated.

Eric W. Biederman (2):
      neigh: Factor out ___neigh_lookup_noref
      neigh: Add helper function neigh_xmit

 include/net/arp.h       | 19 ++++-------------
 include/net/ndisc.h     | 19 +----------------
 include/net/neighbour.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++++
 net/core/neighbour.c    | 54 ++++++++++++++++++++++++++++++++++--------------
 net/decnet/dn_neigh.c   |  6 ++++++
 net/ipv4/arp.c          |  9 +++++++-
 net/ipv6/ndisc.c        |  7 +++++++
 7 files changed, 120 insertions(+), 49 deletions(-)