system lockup on interface deletion/addition

[bol-van]

branch v5.8.7
kernel 5.14.0
ubuntu 20.04

T: Bus=03 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 6 Spd=480 MxCh= 0
D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=0bda ProdID=b812 Rev=02.10
S: Manufacturer=Realtek
S: Product=USB3.0 802.11ac 1200M Adapter
S: SerialNumber=123456
C: #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
I: If#=0x0 Alt= 0 #EPs= 5 Cls=ff(vend.) Sub=ff Prot=ff Driver=rtl88x2bu

Attempt to
iw dev wlan1 del
iw phy phy1 interface add type monitor
lead to command hang and then many other processes also hang so reboot is required
for example :
iw phy (hang)
rmmod 88x2bu (hang)
ping 1.1.1.1 (hang)

[morrownr]

@bol-van

I missed this issue. Are you still looking for help?

[bol-van]

Yes, it reproduces stable. This adapter only works "out of the box" for connecting to AP
Any interface manipulation results in lockup

[morrownr]

This adapter only works "out of the box" for connecting to AP

I cannot argue with you on this statement. I've been hoping to see a new version of this driver that has a lot of fixes. Monitor mode with this driver is not good.

Any interface manipulation results in lockup

My suggestion to fellow Linux users looking to do work with monitor mode is to go to this repo and find a good adapter that uses in-kernel, standards compliant drivers:

https://github.com/morrownr/USB-WiFi

My personal favorite adapters are the ALFA AWUS036ACM (AC1200) and the ALFA AWUS036ACHM (AC600) but there are plenty of others that use in-kernel drivers. There are two BIG advantages to using adapters with in-kernel drivers:

1. The adapters are plug and play in modern Linux distros.
2. They are fully standards compliant. Apps like Aircrack-ng just work. If you want to add an interface. No problem.