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

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Wed, May 11, 2016 at 12:14 PM, George Dunlap
<george.dunlap@xxxxxxxxxx> 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@xxxxxxxxxx>

And this should probably be backported as far back as we're still
doing bugfixes (which I guess would be 4.6 and 4.5?)

 -George

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