Regression in current git - Network Manager fails (bisected)

[Joseph Fannin <jfannin@gmail.com>]

Network Manager (the freedesktop.org one) fails to work with Linus's
current git on a couple of different boxes I have here.  All the boxes
have different NIC types, with different drivers.

I've bisected it down to cd40b7d3983c708aabe3d3008ec64ffce56d33b0 ,
"[NET]: make netlink user -> kernel interface synchronious".  I've
double checked this by testing the kernel as of the immediately
previous commit; Network Manager works with that one, as it did on all
my machines in 2.6.23-mm1.

The netlink change seems to confuse N-M, and it somehow decides that
there's no link beat, so doesn't try to bring up the interface.  If I
run "ifconfig eth0 up", N-M will decide there's a carrier after all
and takes over.  Ethtool detects the link state correctly even with
the interface down.

If I down the interface again with ifconfig, N-M brings it right back
up without a problem, but if I kill N-M, it'll down the interface
before it exits, and fail in the same way as before when restarted.

N-M also emits this error:

"-- Error: Invalid message: type=DONE length=20 flags=<MULTI> sequence-nr=1193012574 pid=1185943630"

...which it doesn't do on kernels where it works normally.
strace'ing NetworkManager shows that it prints that message just after
talking over a netlink socket.

Networking otherwise works fine here with the latest git and N-M, if I
use the ifconfig "trick" to get the link up.

--
Joseph Fannin
jfannin@gmail.com