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Merge branch 'neighbour-namespacify-arp_tbl-and-nd_tbl'

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Kuniyuki Iwashima says:

====================
neighbour: Namespacify arp_tbl and nd_tbl.

The neighbour subsystem is almost ready to drop RTNL.

However, the control paths are serialised by the global
per-table lock.

This series converts arp_tbl and nd_tbl to per-netns table.

With the series, /proc/sys/net/ipv{4,6}/neigh/default/ can
be configured per netns, which was only configurable in
init_net.

To avoid potential regression, all the settings are inherited
from init_net by default, and this behaviour is controlled by
a new sysctl knob, net.core.neigh_inherit_init_net:

  # sysctl net.core.neigh_inherit_init_net
  net.core.neigh_inherit_init_net = 1
  # sysctl net.ipv4.neigh.default.gc_thresh1
  net.ipv4.neigh.default.gc_thresh1 = 128
  # sysctl net.ipv4.neigh.default.gc_thresh1=129
  net.ipv4.neigh.default.gc_thresh1 = 129
  # unshare -n sysctl net.ipv4.neigh.default.gc_thresh1
  net.ipv4.neigh.default.gc_thresh1 = 129

If it is turned off, all settings are reset in the new netns:

  # sysctl net.core.neigh_inherit_init_net=0
  net.core.neigh_inherit_init_net = 0
  # unshare -n sysctl net.ipv4.neigh.default.gc_thresh1
  net.ipv4.neigh.default.gc_thresh1 = 128

Series overview:

  Patch 1 deflakes test_neigh.sh.

  Patch 2 ~ 3 are misc cleanup.

  Patch 4 ~ 7 store arp_tbl/nd_tbl to net->neigh_tables[] and
  remove the global neigh_tables[].

  Patch 8 ~ 9 replace the direct access to arp_tbl/nd_tbl to
  net->neigh_tables[] using new helpers.

  Patch 10 ~ 12 finally replace the global table with per-netns
  table.

  Patch 13 ~ 14 clean up unnecessary net_eq().

  Patch 15 updates test_neigh.sh.

Note that some buggy drivers access nd_tbl without checking
disable_ipv6_mod, so nd_tbl's extern definition is still left.
====================

Link: https://patch.msgid.link/20260902203722.926528-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2026-09-04 15:03:00 -07:00
commit a753848a32
33 changed files with 620 additions and 469 deletions
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14
Documentation/admin-guide/sysctl/net.rst
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27
drivers/infiniband/ulp/ipoib/ipoib_main.c
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10
drivers/net/ethernet/marvell/prestera/prestera_router.c
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29
drivers/net/ethernet/mellanox/mlx5/core/en/rep/neigh.c
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23
drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun_encap.c
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6
drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec.c
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31
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
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10
drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
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14
drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c
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2
drivers/net/ethernet/rocker/rocker_main.c
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2
drivers/net/ethernet/rocker/rocker_ofdpa.c
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8
drivers/net/ethernet/sfc/tc_counters.c
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4
drivers/net/ethernet/sfc/tc_encap_actions.c
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2
drivers/net/vrf.c
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16
drivers/net/vxlan/vxlan_core.c
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10
include/net/arp.h
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20
include/net/ndisc.h
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22
include/net/neighbour.h
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4
include/net/net_namespace.h
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7
include/net/route.h
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4
net/bridge/br_arp_nd_proxy.c
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428
net/core/neighbour.c
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10
net/core/sysctl_net_core.c
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3
net/ieee802154/6lowpan/tx.c
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137
net/ipv4/arp.c
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18
net/ipv4/devinet.c
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7
net/ipv4/fib_semantics.c
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2
net/ipv4/route.c
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17
net/ipv6/addrconf.c
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4
net/ipv6/ip6_output.c
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148
net/ipv6/ndisc.c
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18
net/ipv6/route.c
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66
tools/testing/selftests/net/test_neigh.sh
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