[systemd-devel] Cycle between logind and NetworkManager in case of remote user database

[Andrei Borzenkov]

В Mon, 15 Dec 2014 11:34:17 -0600
Dan Williams <dcbw at redhat.com> пишет:

> 
> On Mon, 2014-12-15 at 16:11 +0100, Lennart Poettering wrote:
> > On Sat, 13.12.14 10:09, Andrei Borzenkov (arvidjaar at gmail.com) wrote:
> > 
> > > NetworkManager sets logind inhibitor lock to monitor for suspend
> > > events. So it implicitly requires logind to be present when NM
> > > starts.
> 
> NM doesn't actually require that, it just wants to know about the
> signals that logind sends and have a chance to respond to them.  If
> logind isn't running, NM shouldn't really care.  But perhaps expectation
> is not matching reality in the code.
> 
> > Any idea what it needs the inhibitor for?
> 
> To be aware of suspend/resume events of course.  NM may want to
> disconnect the network cleanly before suspending, and on resume may need
> to clean up network connections and restart certain operations.
> 
> > > logind is ordered after nss-user-lookup.target. If we have remote
> user
> > > database, it means that logind depends on network to be up and
> running.
> > > 
> > > If network is provided by NetworkManager we have a loop.
> > > 
> > > Due to the fact that NetworkManager service itself does not declare
> > > dependency on logind, it can be pretty hard to recognize.
> > > 
> > > Any idea how it can be solved nicely? I can only think of delaying
> > > inhibitor logic in NM until logind is started. Not sure what side
> > > effects it may have.
> > 
> > Yeah, I figure if they want to be able to run in early parts of boot
> > they should watch logind's bus name and create their inhibitor only
> > after it appears.
> 
> Does logind get D-Bus autolaunched?

Yes.

>                                    NM is just creating a bus proxy for
> the logind DBus service, and then attempting to call a D-Bus method on
> logind to take an inhibitor.  It doesn't actually care that much about
> the result, but NM doesn't pass G_DBUS_CALL_FLAGS_NO_AUTO_START to
> prohibit logind from launching.
> 
> Perhaps NM is requesting logind to start through D-Bus autolaunch, but
> since the network isn't up yet logind then fails itself?
> 

systemd tries to launch logind service which now waits for services it
is ordered After and eventually times out.