Weird issue with r8169: shutdown on carrier comeback

[Tanguy Ortolo <tanguy@ortolo.eu>]

Hello,

I am experiencing a weird computer issue that is at least partly linked 
to the r8169 driver: the computer shuts down when the Ethernet cable is 
pulled off and plugged again. Or when the switch goes down and up again.

To be more specific, the computer is a [Trigkey Key-N100][1] running 
Debian Trixie. That computer has two Gigabit Ethernet controllers:
     $ lspci | grep Ethernet
     01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 15)
     02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 15)

[1]: https://devhome.corp.adobe.com/docs/default/component/ethos-flex/docs/devhome/prerequisites/

One of them is configured, and when I pull off its Ethernet cable and 
plug it again after a few seconds (or if I reboot the switch it is 
connected to), something simulates a power key press (log from 
systemd-logind: “Power key pressed short”). Even though I configured 
logind to ignore such events, one second after this, the computer shuts 
itself down brutally, as if experiencing a power loss.

After a few experiments, I determined that:
* it happens on both Ethernet interfaces of that computer;
* it happens only on _configured_ interfaces: in particular, it does not
   happen if I unplug the Ethernet cable, run `ip link set enp1s0 down`
   and plug the cable again;
* it does not happen with the proprietary driver r8168.

I am not really sure the r8169 driver is at fault here; it sounds more 
like a very weird hardware issue in specific conditions, which are met 
when using it. Anyway, I though you deserved to know, in case it could 
be useful. Please tell me if there is anything else I could do to 
further diagnose that issue.

Regards,

-- 
Tanguy Ortolo