Re: [PATCH 4/4] migration: Remove dependency to TYPE_DEVICE

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Jun 05, 2026 at 12:30:01PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Fri, Jun 5, 2026 at 3:12 AM Peter Xu <peterx@redhat.com> wrote:
> >
> > While doing that, we still want to keep the Property list that migration
> > object used to use.  Apply them directly to ObjectClass instead of setting
> > them with a DeviceClass.
> >
> > Manually apply the two extra properties (compat properties, global
> > settings) in an instance_post_init() hook, just like most of the rest
> > users, see callers of object_apply_compat_props().
> >
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  migration/migration.h |  2 +-
> >  migration/migration.c | 33 +++++++++++++++++++--------------
> >  2 files changed, 20 insertions(+), 15 deletions(-)
> >
> > diff --git a/migration/migration.h b/migration/migration.h
> > index 841f49b215..8bdb8e8e6b 100644
> > --- a/migration/migration.h
> > +++ b/migration/migration.h
> > @@ -274,7 +274,7 @@ struct MigrationClass {
> >
> >  struct MigrationState {
> >      /*< private >*/
> > -    DeviceState parent_obj;
> > +    Object parent_obj;
> >
> 
> You need to change MigrationClass.parent_class too

Do we even need a MigrationClass struct ? It has nothing except
the parent_class field, so feels redundant. Could the code just
use  OBJECT_DECLARE_SIMPLE_TYPE instead.

> 
> >      /*< public >*/
> >      QemuThread thread;
> > diff --git a/migration/migration.c b/migration/migration.c
> > index 074d3f2c69..f9f102e78a 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -3966,11 +3966,9 @@ fail:
> >
> >  static void migration_class_init(ObjectClass *klass, const void *data)
> >  {
> > -    DeviceClass *dc = DEVICE_CLASS(klass);
> > -
> > -    dc->user_creatable = false;
> > -    device_class_set_props_n(dc, migration_properties,
> > -                             migration_properties_count);
> > +    for (int i = 0; i < migration_properties_count; i++) {
> > +        object_class_add_property(klass, &migration_properties[i]);
> > +    }

This could get rid of migration_properties array indirection and call
object_class_property_add directly, avoiding the need for the previous
patch.

> > +static const TypeInfo migration_type = {
> > +    .name = TYPE_MIGRATION,
> > +    .parent = TYPE_OBJECT,
> >      .class_init = migration_class_init,
> > -    .class_size = sizeof(MigrationClass),
> > +    .class_size = sizeof(ObjectClass),
> 
> and this should still be MigrationClass

Not if we use OBJECT_DECLARE_SIMPLE_TYPE

> 
> >      .instance_size = sizeof(MigrationState),
> >      .instance_init = migration_instance_init,
> > +    .instance_post_init = migration_instance_post_init,
> >      .instance_finalize = migration_instance_finalize,
> >  };
> >
> > --
> > 2.53.0
> >
> >
> 
> Otherwise, the series is good to me!
> 

With regards,
Daniel
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