Re: Network script is invoked twice - in parallel!

[Sven Köhler <sven.koehler@xxxxxxxxx>]

Hi James,

Am 09.05.23 um 09:28 schrieb James Dingwall:
> On Sat, May 06, 2023 at 03:42:15PM +0200, Sven Köhler wrote:
> > Hi all,
> >
> > I observe that my networking script is invoked twice - in parallel! - when I
> > execute "xl create ..." or reboot a domU.
> > I added the following the beginning/end of my script:
> >
> > > echo "$$ ${command} ${dev} ${ip} | $@" >>/tmp/xen.log
> > > ...
> > > echo "$$ done" >>/tmp/xen.log
> >
> > The output is:
> >
> > > 1575914 online vif34.0 195.x.x.x 2a01:x:x:x:x::2/66 | online type_if=vif
> > > 1575916 online vif34.0 195.x.x.x 2a01:x:x:x:x::2/66 | online type_if=vif
> > > 1575914 done
> > > 1575916 done
> >
> > I am using Xen 4.17.1.
> >
> > How can I prevent that from happening? The script fails randomly since it is
> > executed in parallel twice!
> >
> > I would expect that the script is executed once only.
> I don't think that is expected...  I think there are three ways that the
> hotplug event can be handled:
>
> - udev rules (deprecated?)
> - `xl devd` (required in a domU driver domain)
> - directly from `xl create`
>
> If you've done an upgrade are there some old udev rules hanging around?  If
> not do you have an `xl devd` process running?  systemd unit
> xendriverdomain.service or /etc/init.d/xendriverdomain, the init.d script
> looks to have a check to not run in dom0 but the systemd unit doesn't have
> the same.
xendriverdomain was enabled and was indeed invoking the script in 
addition to xl create. I would have seen that, I guess, if I had looked 
into the parent process.
Thanks for the hint!


Kind Regards,
  Sven