Re: [Qemu-devel] [PATCH 3/8] RunState: Add additional states

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 2 Sep 2011 11:28:18 -0300
Luiz Capitulino <lcapitulino@redhat.com> wrote:

> On Thu, 01 Sep 2011 22:58:51 +0200
> Jan Kiszka <jan.kiszka@web.de> wrote:
> 
> > On 2011-09-01 20:39, Luiz Capitulino wrote:
> > > On Thu, 01 Sep 2011 20:30:57 +0200
> > > Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > 
> > >> On 2011-09-01 20:12, Luiz Capitulino wrote:
> > >>> Currently, only vm_start() and vm_stop() change the VM state.
> > >>> That's, the state is only changed when starting or stopping the VM.
> > >>>
> > >>> This commit adds the runstate_set() function, which makes it possible
> > >>> to also do state transitions when the VM is stopped or running.
> > >>>
> > >>> Additional states are also added and the current state is stored.
> > >>>
> > >>> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> > >>> ---
> > >>>  cpus.c      |    1 +
> > >>>  migration.c |    8 +++++++-
> > >>>  sysemu.h    |   10 +++++++++-
> > >>>  vl.c        |   20 ++++++++++++++++++++
> > >>>  4 files changed, 37 insertions(+), 2 deletions(-)
> > >>>
> > >>
> > >> ...
> > >>
> > >>> diff --git a/vl.c b/vl.c
> > >>> index f0b56a4..59f71fc 100644
> > >>> --- a/vl.c
> > >>> +++ b/vl.c
> > >>> @@ -321,6 +321,22 @@ static int default_driver_check(QemuOpts *opts, void *opaque)
> > >>>  }
> > >>>  
> > >>>  /***********************************************************/
> > >>> +/* QEMU state */
> > >>> +
> > >>> +static RunState current_run_state = RSTATE_NO_STATE;
> > >>> +
> > >>> +bool runstate_check(RunState state)
> > >>> +{
> > >>> +    return current_run_state == state;
> > >>> +}
> > >>> +
> > >>> +void runstate_set(RunState state)
> > >>> +{
> > >>> +    assert(state < RSTATE_MAX);
> > >>> +    current_run_state = state;
> > >>
> > >> I still think this should check for valid state transitions instead of
> > >> blindly accepting what the caller passes in.
> > > 
> > > I thought your comment where more like a future enhancement than
> > > a request for change.
> > 
> > I think we want this now to document at a central place which
> > transitions are valid and which not. State machines without such checks
> > break sooner or later, subtly.
> 
> Ok, I'll do it.

I did it in v4 (just sent). But it wasn't trivial to do and to test, so
a careful review of that patch is very appreciated.