igc: Fix LED-related deadlock on driver unbind

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: ea578703b03d ("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.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

igc: Add support for LEDs on i225/i226

Add support for LEDs on i225/i226. The LEDs can be controlled via sysfs
from user space using the netdev trigger. The LEDs are named as
igc-<bus><device>-<led> to be easily identified.

Offloading link speed and activity are supported. Other modes are simulated
in software by using on/off. Tested on Intel i225.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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/20240213184138.1483968-1-anthony.l.nguyen@intel.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>