Network Stack Deadlock

[jackburton]

Yesterday I was doing some tests with the network stack, and after a while, I experienced a deadlock. ifconfig was locked and couldn't be killed (even with kill -9). net_server was locked, too. I then entered KDL, and had a look at the threads involved. There was a deadlock between ifconfig and wpa_supplicant. The net_interfaces mutex was held by wpa_supplicant, which was waiting on the mutex of the wireless interface, which in turn was held by ifconfig. So I guess we have a lock inversion somewhere. It's reproducible here 100% of the times by doing: ifconfig /dev/net/<wireless_card> down while wpa_supplicant is scanning the available networks. I have an ipro3945 wireless card.