Re: [PATCH iwl-net 0/3] ice: fix RTNL vs auxiliary device lock inversion

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

> A window entry is a contended device_trylock(), that is, the exact
> moment really_probe() holds the auxiliary device lock and waits for the
> RTNL lock, so each one is an occasion that used to close the cycle.
> Without the series the console shows both halves and the box only
> returns through hung_task_panic. 25 reboots on the patched kernel were
> clean.
> 
> Petr Oros (3):
>    ice: avoid RTNL deadlock when notifying the RDMA auxiliary driver
>    ice: do not block on the aux device lock in ethtool set_channels
>    ice: do not block on the aux device lock in ndo_setup_tc
> 
>   drivers/net/ethernet/intel/ice/ice_dcb_lib.c |  9 +++++++-
>   drivers/net/ethernet/intel/ice/ice_ethtool.c |  6 +++++-
>   drivers/net/ethernet/intel/ice/ice_idc.c     | 20 ++++++++++++++----
>   drivers/net/ethernet/intel/ice/ice_idc_int.h |  2 +-
>   drivers/net/ethernet/intel/ice/ice_main.c    | 22 +++++++++++++++-----
>   5 files changed, 47 insertions(+), 12 deletions(-)
> 

trylock is clearly an antipattern, but we don't have anything better,
especially for a -net material

side note: we have resolved the same issue via rtnl_unlock()&relock()
in OOT (to be published within days), which is even worse anti-pattern

Would be best to have proper API as -next thing, glad to hear your
support on that!

side note2: I have a few fixes around the thing you touches, but no
conflicts so far, will CC you