[PATCHv2 net 0/3] bonding: fix negotiation flapping in 802.3ad passive mode

[Hangbin Liu <liuhangbin@gmail.com>]

This patch fixes unstable LACP negotiation when bonding is configured in
passive mode (`lacp_active=off`).

Previously, the actor would stop sending LACPDUs after initial negotiation
succeeded, leading to the partner timing out and restarting the negotiation
cycle. This resulted in continuous LACP state flapping.

The fix ensures the passive actor starts sending periodic LACPDUs after
receiving the first LACPDU from the partner, in accordance with IEEE
802.1AX-2020 section 6.4.1.

v2:
a) Split the patch in to 2 parts. One for lacp_active setting.
   One for passive mode negotiation flapping issue. (Nikolay Aleksandrov)
b) Update fixes tags and some comments (Nikolay Aleksandrov)
c) Update selftest to pass on normal kernel (Jakub Kicinski)


Hangbin Liu (3):
  bonding: update LACP activity flag after setting lacp_active
  bonding: send LACPDUs periodically in passive mode after receiving
    partner's LACPDU
  selftests: bonding: add test for passive LACP mode

 drivers/net/bonding/bond_3ad.c                | 67 +++++++++----
 drivers/net/bonding/bond_options.c            |  1 +
 include/net/bond_3ad.h                        |  1 +
 .../selftests/drivers/net/bonding/Makefile    |  3 +-
 .../drivers/net/bonding/bond_passive_lacp.sh  | 95 +++++++++++++++++++
 5 files changed, 148 insertions(+), 19 deletions(-)
 create mode 100755 tools/testing/selftests/drivers/net/bonding/bond_passive_lacp.sh

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2.46.0