Re: [PATCH for-4.7 2/2] tools/xendomains: Create lockfile on start unconditionally

[Wei Liu <wei.liu2@citrix.com>]

On Wed, May 11, 2016 at 12:19:45PM +0100, George Dunlap wrote:
> On 11/05/16 12:14, George Dunlap wrote:
> > At the moment, the xendomains init script will only create a lockfile
> > if when started, it actually does something -- either tries to restore
> > a previously saved domain as a result of XENDOMAINS_RESTORE, or tries
> > to create a domain as a result of XENDOMAINS_AUTO.
> > 
> > RedHat-based SYSV init systems try to only call "${SERVICE} shutdown"
> > on systems which actually have an actively running component; and they
> > use the existence of /var/lock/subsys/${SERVICE} to determine which
> > systems are running.
> > 
> > This means that at the moment, on RedHat-based SYSV systems (such as
> > CentOS 6), if you enable xendomains, and have XENDOMAINS_RESTORE set
> > to "true", but don't happen to start a VM, then your running VMs will
> > not be suspended on shutdown.
> > 
> > Since the lockfile doesn't really have any other effect than to
> > prevent duplicate starting, just create it unconditionally every time
> > we start the xendomains script.
> > 
> > The other option would have been to touch the lockfile if
> > XENDOMAINS_RESTORE was true regardless of whether there were any
> > domains to be restored.  But this would mean that if you started with
> > the xendomains script active but XENDOMAINS_RESTORE set to "false",
> > and then changed it to "true", then xendomains would still not run the
> > next time you shut down.  This seems to me to violate the principle of
> > least surprise.
> > 
> > Signed-off-by: George Dunlap <george.dunlap@citrix.com>
> > ---
> > CC: Ian Jackson <ian.jackson@citrix.com>
> > CC: Wei Liu <wei.liu2@citrix.com>
> > CC: Olaf Hering <olaf@aepfle.de>
> 
> Forgot the release justification.
> 
> This is a bug in xendomains under RHEL sysv init systems -- albeit one
> that's been there from the beginning.  Creating the lockfile
> unconditionally shouldn't cause any problems as far as I can tell.
> 

I agree.

Release-acked-by: Wei Liu <wei.liu2@citrix.com>

I've queued this series.

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