[PATCH net 0/2] net: ethtool: netlink: Fix notifications for

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

It has been found (thanks to Parthiban) that the PLCA ethtool commands
were failing since 6.12, due to the phy_link_topology work. This was
traced back to the ethnl notifications mechanism, in which calls to
ethnl_req_get_phydev() crashed in the notification path following a
->set request.

The typical callsite for ethnl_req_get_phydev() looks like :

    phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],
				  info->extack);

as 'tb' is NULL in the notification path for the ->prepare_data ethnl
ops, this causes crashes. The solution for that is to change the
prototype of ethnl_req_get_phydev() to perform checks inside the helper
(patch 1).

While investigating that, I realised that the notification path for PHYs
is not correct anyways. As we don't have a netlink request to parse, we
can't know for sure which PHY the notification event targets in the case
of a notification following a ->set request.

Patch 2 introduces a context structure that is used between ->set
requests and the followup notification, to keep track of the PHY that
the original request targeted for the notification.

Thanks Parthiban for the report (not on netdev@ though).

Maxime

Maxime Chevallier (2):
  net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device
  net: ethtool: netlink: Pass a context for default ethnl notifications

 net/ethtool/cabletest.c |  8 ++++----
 net/ethtool/linkstate.c |  2 +-
 net/ethtool/netlink.c   | 21 +++++++++++++++++----
 net/ethtool/netlink.h   |  5 +++--
 net/ethtool/phy.c       |  2 +-
 net/ethtool/plca.c      |  6 +++---
 net/ethtool/pse-pd.c    |  4 ++--
 net/ethtool/stats.c     |  2 +-
 net/ethtool/strset.c    |  2 +-
 9 files changed, 33 insertions(+), 19 deletions(-)

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2.48.1