Panic when unplugging Thunderbolt <-> USB <-> Ethernet dongle

Panic when unplugging Thunderbolt <-> USB <-> Ethernet dongle

[Alex Musolino]

Hi all,

Trying to netboot 9front on a Dell Precision 5220.  Unfortunately, the
provided Thunderbolt dongle thing doesn't seem to work.  Manually
running nusb/ether appears to succeed, but ip/ipconfig hangs
indefinitely.  Killing it (ip/ipconfig) seems to then leave the driver
in a strange state.

Apart from not working, and the real reason for all this noise, is
that it causes the following panic when unplugged:

ktrace /amd64/9pc64 0xffffffff80116947 0xffffffff810cc298 <<EOF
	estackx ffffffff810cc7d
	810cc1b8=801166a1 810cc230=80229181 810cc268=80116947 810cc290=80116947
	810cc298=801166a9 810cc2a8=80161002 810cc3f8=80116cd0 810cc408=801d1db3
	810cc4a0=80111726 810cc4c8=80116050 810cc538=80209ef0 810cc560=80209ef0
	810cc578=801ef097 810cc5a0=801ef097 810cc5b8=801106f4 810cc5d0=801d2b01
	810cc658=801d1db3 810cc688=80227db8 810cc698=801d1e0a 810cc6d8=802282a6
	810cc6e0=801d20a9 810cc700=801d1c0a 810cc708=801ef446 810cc728=801d2023
	810cc740=801d2a14 810cc750=801d2b57 810cc760=801d2950 810cc7b8=80117a43
	810cc7c0=00000000 810cc7c8=00000000 810cc7d0=80117a2a
	EOF
src(0xffffffff80116947); // dumpstack+0x10
src(0xffffffff80161002); // panic+0xeb
src(0xffffffff80116cd0); // faultamd64+0xa0
src(0xffffffff80116050); // trap+0x177
src(0xffffffff801106f4); // _strayintr+0x4e
//didn't find pc at sp=0xffffffff810cc5c0, last pc found at sp=0xffffffff810cc5b8

--
Cheers,
Alex Musolino