iflib: Create led(4) devices

[kbowling]

Summary

If the driver defines an led_func, have the framework create them during attach.

PR: 246885
Reported by: Jose Luis Duran <[e-mail]>

Test Plan

Tested on I350:
echo "f3" > /dev/led/igb0
echo "0" > /dev/led/igb0

[kbowling]

Jose submitted a variant where the driver (e1000 in this case) calls the iflib_led_create() function in its post attach. I am open to either approach if anyone has any thoughts one way or the other.

[jlduran]

I prefer this approach.

Regardless of which patch you choose, on my home router (2 i211-based NICs), identifying /dev/led/igb0 works, but /dev/led/igb1 do not.

Nevertheless, the LED devices are created as well. Thank you!

[markj]

Seems ok. This kind of reflection looks a bit hacky but I see it used elsewhere. Probably we should have some kobj.h helper to do it.

sys/net/iflib.c

5253

And on the next line too.

5257