Re: [Qemu-devel] [PATCH f0r 2.11] runstate/migrate: Two more transitions

[Peter Xu <peterx@redhat.com>]

On Mon, Aug 07, 2017 at 01:25:29PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (peterx@redhat.com) wrote:
> > On Fri, Aug 04, 2017 at 06:50:11PM +0100, Dr. David Alan Gilbert (git) wrote:
> > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > > 
> > > There's a race if someone does a 'stop' near the end of migrate;
> > > the migration process goes through two runstates:
> > >     'finish migrate'
> > >     'postmigrate'
> > > 
> > > If the user issues a 'stop' between the two we end up with invalid
> > > state transitions.
> > > Add the transitions as valid.
> > > 
> > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > > ---
> > >  vl.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/vl.c b/vl.c
> > > index 99fcfa0442..bacb03f49d 100644
> > > --- a/vl.c
> > > +++ b/vl.c
> > > @@ -621,6 +621,7 @@ static const RunStateTransition runstate_transitions_def[] = {
> > >  
> > >      { RUN_STATE_PAUSED, RUN_STATE_RUNNING },
> > >      { RUN_STATE_PAUSED, RUN_STATE_FINISH_MIGRATE },
> > > +    { RUN_STATE_PAUSED, RUN_STATE_POSTMIGRATE },
> > >      { RUN_STATE_PAUSED, RUN_STATE_PRELAUNCH },
> > >      { RUN_STATE_PAUSED, RUN_STATE_COLO},
> > >  
> > > @@ -633,6 +634,7 @@ static const RunStateTransition runstate_transitions_def[] = {
> > >      { RUN_STATE_PRELAUNCH, RUN_STATE_INMIGRATE },
> > >  
> > >      { RUN_STATE_FINISH_MIGRATE, RUN_STATE_RUNNING },
> > > +    { RUN_STATE_FINISH_MIGRATE, RUN_STATE_PAUSED },
> > >      { RUN_STATE_FINISH_MIGRATE, RUN_STATE_POSTMIGRATE },
> > >      { RUN_STATE_FINISH_MIGRATE, RUN_STATE_PRELAUNCH },
> > >      { RUN_STATE_FINISH_MIGRATE, RUN_STATE_COLO},
> > 
> > Do we need this as well?
> > 
> >     { RUN_STATE_POSTMIGRATE, RUN_STATE_PAUSED },
> 
> Apparently not:
> 
> (qemu) migrate "exec:cat > /dev/null"
> (qemu) infomigrate
> unknown command: 'infomigrate'
> (qemu) info status
> VM status: paused (postmigrate)
> (qemu) stop
> (qemu) info status
> VM status: paused (postmigrate)
> (qemu)
> 
> 
> so doing a stop at that point doesn't seem to cause any problem.

Yes. Thanks.

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu