On Mon, Aug 06, 2012 at 06:04:11PM +0200, Kay Sievers wrote: > On Mon, Aug 6, 2012 at 5:52 PM, Daniel P. Berrange <[email protected]> > wrote: > > For libvirt, we (will soon) have a daemon (virtlockd) which maintains > > exclusive fcntl() based locks on disk images/devices, on behalf of both > > libvirtd and any running QEMU or LXC instances. This is a safety critical > > daemon (hence separate from libvirtd), to the extent that if the daemon > > stops / crashes, the entire host should be immediately fenced using a > > kernel watchdog and/or hardware power control device. > > > > We still want to be able to restart this daemon during RPM upgrades to > > newer versions, but we can't use a normal stop+start sequence, because > > that will loose locks for any active VMs. Thus the daemon has the ability > > to re-exec() itself triggered by SIGUSR1, preserving its critical state. > > I've read the manpages for .service, .exec, etc but I've not seen any > > reference to changing config such that > > > > # systemctl restart virtdlockd.service > > > > will simply send SIGUSR1 to the process, instead of stopping it and then > > starting it again. Obviously I could make the RPM %post send SIGUSR1 > > directly and ignore systemctl, but that doesn't help admins who just > > expect to use systemctl. So I want to know if there is a recommended > > way to handle this kind of use case ? > > $ systemctl reload ... ?
I thought about reload, but using that to re-exec the daemon seemed a little evil to me, since it was really for just reloading config files. > or with the signal speficied: > > $ systemctl kill ... True, I guess I could use that. I'm infering from your response that there's no way to customize what 'restart' does, as you can do with stop/start/reload/etc. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ systemd-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/systemd-devel
