Roman reports a deadlock on unplug of a Thunderbolt docking station
containing an Intel I225 Ethernet adapter.

The root cause is that led_classdev's for LEDs on the adapter are
registered such that they're device-managed by the netdev.  That
results in recursive acquisition of the rtnl_lock() mutex on unplug:

When the driver calls unregister_netdev(), it acquires rtnl_lock(),
then frees the device-managed resources.  Upon unregistering the LEDs,
netdev_trig_deactivate() invokes unregister_netdevice_notifier(),
which tries to acquire rtnl_lock() again.

Avoid by using non-device-managed LED registration.

Stack trace for posterity:

  schedule+0x6e/0xf0
  schedule_preempt_disabled+0x15/0x20
  __mutex_lock+0x2a0/0x750
  unregister_netdevice_notifier+0x40/0x150
  netdev_trig_deactivate+0x1f/0x60 [ledtrig_netdev]
  led_trigger_set+0x102/0x330
  led_classdev_unregister+0x4b/0x110
  release_nodes+0x3d/0xb0
  devres_release_all+0x8b/0xc0
  device_del+0x34f/0x3c0
  unregister_netdevice_many_notify+0x80b/0xaf0
  unregister_netdev+0x7c/0xd0
  igc_remove+0xd8/0x1e0 [igc]
  pci_device_remove+0x3f/0xb0

Fixes: ea578703 ("igc: Add support for LEDs on i225/i226")
Reported-by: Roman Lozko <lozko.roma@gmail.com>
Closes: https://lore.kernel.org/r/CAEhC_B=ksywxCG_+aQqXUrGEgKq+4mqnSV8EBHOKbC3-Obj9+Q@mail.gmail.com/Reported-by: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
Closes: https://lore.kernel.org/r/ZhRD3cOtz5i-61PB@mail-itl/Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Tested-by: Kurt Kanzenbach <kurt@linutronix.de> # Intel i225
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20240422204503.225448-1-anthony.l.nguyen@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>