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vxlan: Join / leave MC group when reconfigured

Petr Machata linux-kselftest netdev 2 versions – Applied

Status from this message: This series was applied to netdev/net-next.git (main)

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Versions newest first · linked by author and title

  1. v2 Latest5 patches 1 replyApplied 5/5
  2. v14 patches 5 repliesSuperseded

Changes in v2 from the cover letter

- Patch #1:
- New patch.
- Patch #2:
- Adjust the code so that it is closer to vnifilter. Expand the commit message the explain in detail which aspects of vnifilter code were emulated.

Patches in v2 All 5 applied

#Subject and filesSizeRepliesApplied
1/5vxlan: Drop 'changelink' parameter from vxlan_dev_configure()drivers/net/vxlan/vxlan_core.c+3 -30 repliesApplied
2/5vxlan: Join / leave MC group after remote changesdrivers/net/vxlan/vxlan_core.c+16 -20 repliesApplied
3/5selftests: forwarding: lib: Move require_command to net, generalizetools/testing/selftests/net/forwarding/lib.sh tools/testing/selftests/net/lib.sh+19 -100 repliesApplied
4/5selftests: test_vxlan_fdb_changelink: Convert to lib.shtools/testing/selftests/net/test_vxlan_fdb_changelink.sh+24 -150 repliesApplied
5/5selftests: test_vxlan_fdb_changelink: Add a test for MC remote changetools/testing/selftests/net/test_vxlan_fdb_changelink.sh+76 -00 repliesApplied

Reviews trailers per patch

All 5 patches have a Reviewed-by or Acked-by of their own; the series has one for all of them.

PatchIdo SchimmelNikolay Aleksandrov
SeriesR-b
1/5R-b
2/5R-b
3/5R-b R-b
4/5R-b R-b
5/5R-b R-b

Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.

Read the v2 thread

Cover letter [PATCH net-next v2 0/5] vxlan: Join / leave MC group when reconfigured

When a vxlan netdevice is brought up, if its default remote is a multicast address, the device joins the indicated group.

Therefore when the multicast remote address changes, the device should leave the current group and subscribe to the new one. Similarly when the interface used for endpoint communication is changed in a situation when multicast remote is configured. This is currently not done.

Both vxlan_igmp_join() and vxlan_igmp_leave() can however fail. So it is possible that with such fix, the netdevice will end up in an inconsistent situation where the old group is not joined anymore, but joining the new group fails. Should we join the new group first, and leave the old one second, we might end up in the opposite situation, where both groups are joined. Undoing any of this during rollback is going to be similarly problematic.

One solution would be to just forbid the change when the netdevice is up. However in vnifilter mode, changing the group address is allowed, and these problems are simply ignored (see vxlan_vni_update_group()):

 # ip link add name br up type bridge vlan_filtering 1
 # ip link add vx1 up master br type vxlan external vnifilter local 192.0.2.1 dev lo dstport 4789
 # bridge vni add dev vx1 vni 200 group 224.0.0.1
 # tcpdump -i lo &
 # bridge vni add dev vx1 vni 200 group 224.0.0.2
 18:55:46.523438 IP 0.0.0.0 > 224.0.0.22: igmp v3 report, 1 group record(s)
 18:55:46.943447 IP 0.0.0.0 > 224.0.0.22: igmp v3 report, 1 group record(s)
 # bridge vni
 dev               vni                group/remote
 vx1               200                224.0.0.2

Having two different modes of operation for conceptually the same interface is silly, so in this patchset, just do what the vnifilter code does and deal with the errors by crossing fingers real hard.

v2:
- Patch #1:
- New patch.
- Patch #2:
- Adjust the code so that it is closer to vnifilter. Expand the commit message the explain in detail which aspects of vnifilter code were emulated.

Petr Machata (5):
vxlan: Drop 'changelink' parameter from vxlan_dev_configure()
vxlan: Join / leave MC group after remote changes
selftests: forwarding: lib: Move require_command to net, generalize
selftests: test_vxlan_fdb_changelink: Convert to lib.sh
selftests: test_vxlan_fdb_changelink: Add a test for MC remote change

 drivers/net/vxlan/vxlan_core.c                |  24 +++-
 tools/testing/selftests/net/forwarding/lib.sh |  10 --
 tools/testing/selftests/net/lib.sh            |  19 +++
 .../net/test_vxlan_fdb_changelink.sh          | 111 ++++++++++++++++--
 4 files changed, 136 insertions(+), 28 deletions(-)
Signature · 1 line
2.47.0