[PATCH net v2 0/2] net: openvswitch: fix a feature leak on a failed change

[Minxi Hou <houminxi@gmail.com>]

Changes in v2:
- Patch 1 limits its closing claim to OVS_DP_CMD_SET, and says that a
  failed OVS_DP_CMD_NEW and the reset that follows it still leave the
  key one enable ahead.
- Patch 1 names the reachability and the effect: only CAP_NET_ADMIN is
  needed, datapath_policy does not validate the per-cpu-pids attribute,
  and a disable on a count of zero warns in static_key_dec_not_one().
- Patch 2 treats only EOPNOTSUPP as the missing key and skips with the
  kselftest skip code; any other failure fails the test.
- Patch 2 selects CONFIG_NET_CLS_ACT and CONFIG_NET_TC_SKB_EXT in the
  selftest config fragment, so the recirc round runs in CI.
- Patch 2 sends the features the datapath reports when --features is
  left out, instead of clearing them.

v1: https://lore.kernel.org/netdev/20261107113403.797779-1-houminxi@gmail.com/

ovs_dp_change() records the requested user features before it calls the
update that can fail, so a request rejected for an empty per-cpu-pids
leaves the datapath claiming a feature it never enabled. The tc skb
extension key is a reference count shared with cls_flower, and the code
that would keep it in step is skipped on that path.

Patch 1 fixes the ordering. Patch 2 adds a set-dp command to the
openvswitch selftest tool, and a test that sends such a request and
checks the features the datapath reports afterwards. It fails without
the fix and passes with it.

The problem turned up while the YNL spec for this family was being
written: describing the ovs_datapath set command meant reading
ovs_dp_change(), where the ordering stands out.

Signed-off-by: Minxi Hou <houminxi@gmail.com>

Minxi Hou (2):
Minxi Hou (2):
  net: openvswitch: do not record user features when the change fails
  selftests/net/openvswitch: check that a failed set keeps the features

 net/openvswitch/datapath.c                    | 10 +--
 .../testing/selftests/net/openvswitch/config  |  2 +
 .../selftests/net/openvswitch/openvswitch.sh  | 67 +++++++++++++++++++
 .../selftests/net/openvswitch/ovs-dpctl.py    | 53 +++++++++++++++
 4 files changed, 127 insertions(+), 5 deletions(-)


base-commit: 30c71476d842b094651bd7712f6c8ee8716147d0
-- 
2.56.0