[systemd-devel] Synchronization Between Services at Shutdown

[Kurt von Laven]

Both services A and B specify Requires=dbus.service and After=dbus.service.
If I am interpreting everything that's being said correctly, there is a
race condition in my code since service A's implementation doesn't require
it to wait until it has processed the method call from service B before it
stops listening for method calls. Does that sound right?

On Thu, Apr 2, 2015 at 6:31 AM, Lennart Poettering <lennart at poettering.net>
wrote:

> On Thu, 02.04.15 13:07, Michael Biebl (mbiebl at gmail.com) wrote:
>
> > 2015-04-02 13:03 GMT+02:00 Lennart Poettering <lennart at poettering.net>:
> > > On Thu, 02.04.15 13:00, Michael Biebl (mbiebl at gmail.com) wrote:
> > >
> > >> 2015-04-02 11:06 GMT+02:00 Lennart Poettering <lennart at poettering.net
> >:
> > >> > If you want to ensure that bus communication still works in your
> > >> > shutdown code, you hence need to make sure you place
> > >> > After=dbus.service in your services, so that you are shut down
> before
> > >> > dbus is.
> > >>
> > >> Type=dbus service currently only get a dependency on dbus.socket (via
> > >> After=basic.target).
> > >
> > > Yeah, and rightfully so. I mean, a service really should be able to
> > > shutdown if dbus is dead. In fact, it should be able to shutdown in
> > > pretty much any situation...
> >
> > Apparently they don't. There were all sorts of failures caused by dbus
> > being shut down too early.
> >
> > https://bugs.launchpad.net/ubuntu/+source/dbus/+bug/1438612 is one of
> > the related bug reports afair.
>
> Hmm? I really don't see how the NFS vs wpa_supplicant issue has
> anything to do with dbus? NFS doesn't care about dbus at all...
>
> You need to order wpa_supplicant and NM Before=remote-fs-pre.target
> and pull it it via Wants=remote-fs-pre.target. With that in place
> during shutdown the mounts will be unmounted first, and NM/wpa only
> shut down after that. See systemd.special(7) for details.
>
> I really don't see what dbus has to do with all this...
>
> Lennart
>
> --
> Lennart Poettering, Red Hat
>



-- 
Kurt von Laven | Endless Mobile |  EndlessM.com <http://endlessm.com/>
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