[Gnewsense-dev] 2.6.32-libre-lemote vs NetworkManager (race condition?)

[Alexandre Oliva]

I've been experiencing loss of wired networking with NetworkManager
since I started using 2.6.32-libre-lemote, that don't seem to ever occur
with 2.6.31.7-libre2-lemote.

My setup uses a DHCP-configured wired network interface, with the WiFi
module blacklisted.

The network is always brought up early in the boot, and remains on for
at least 45 seconds, but quite often NetworkManager decides that dhcp
took too long (>45 seconds) to complete and reverts to a local IP
address, 169.254.some.thing IIRC.  It doesn't seem to recover from that
by itself; resetting the network connection after logging in as a
desktop user works; unplugging the cable and plugging it back it, or
restarting network-manager fix the problem, but sometimes only
temporarily, for another 45 seconds.

It appears to be some race condition involving dbus, dhcbdb and the
dbus-send notification in /etc/dhcp3/dhclient-exit-hooks.d/dhcdbd, but
it's hard to tell for sure.  If I strace the system dbus-daemon and/or
dhcbdb and then restart network-manager, the connection goes dead after
another 45 seconds.  If I don't strace anything, or if I strace -f
dhcbdb, sometimes it survives, sometimes it dies in the same way.

I have strace logs that worked and failed, and AFAICT the dbus-send
notification issued by dhclient-exit-hooks.d/dhcdbd doesn't get to
dhcdbd on traces in which the connection dies, whereas it does when it
survives.  I'm guessing (from the little I know about dbus) that the
race has to do with dhcdbd registering with dbus-daemon to receive
messages from dhcdbd, but that's just a guess: I don't really know how
dbus decides whom to relay messages to.

Is anyone else experiencing this?  Anyone familiar with dbus and
dhclient willing to offer a more informed guess as to where the problem
might be?

Thanks in advance,

-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer