WDS stopped working in 21.02, looking for bug in netifd

[Daniel Haid]

I have continued investigating.

After all, it seems that the interface being down is just a symptom.

I summarize my current findings:

With the 21.02 netifd version, there seems to be a bug concerting WDS. 
The bug has the following effect:

I have openwrt 21.02 running on one system running as WDS AP and another 
one running as WDS Client. The WDS Client is running and its 
configuration never changed.

After booting the WDS AP, there are two possibilities for in what state 
the system can be, I call them NON-WORKING and WORKING. The probability 
seems to be about 50% to be in one or the other state after booting.

To find out in which state I am after booting, I look for the interface 
wlan0.sta1. If it is UP, then we are in state WORKING. If it is DOWN, 
then we are in state NON-WORKING.

Using ping, in state WORKING, the AP can reach the Client. In state 
NON-WORKING, the AP cannot reach the Client.

In state WORKING, the interface wlan0.sta1 can be set to DOWN and UP 
again, and the AP can then again ping the Client, but only after waiting 
about 4 minutes for the Client to reconnect to the AP (in my last mail, 
I wrote that it did not work, but I just did not wait long enough).

In state NON-WORKING, I can set the interface wlan0.sta1 to UP, but this 
will not help. The ip command will show that the interface is UP, but 
the AP can not ping the Client, no matter how long I wait after setting 
the state to UP.

If I turn off the Client, wait for the interface wlan0.sta1 to be 
removed on the AP, and then restart the Client, then the interface 
wlan0.sta1 will be created again, in state DOWN. Everything is again as 
in the state NON-WORKING.

To reliably reach the state NON-WORKING, run "/etc/init.d/network restart".

Changing the function wireless_interface_handle_link such that it does 
not call interface_handle_link when it is called from 
wireless_device_hotplug_event fixes the bug.

But I do not understand what is happening.

I am not subscribed to the list; please send Cc to me.

D.H.