Re: [PATCH 50/55] s390x/event-facility: Simplify creation of SCLP event devices

[David Hildenbrand <david@redhat.com>]

On 19.05.20 16:55, Markus Armbruster wrote:
> init_event_facility() creates the SCLP events bus with two SCLP event
> devices (sclpquiesce and sclp-cpu-hotplug).  It leaves the devices
> unrealized.  A comment explains they will be realized "via the bus".
> 
> The bus's realize method sclp_events_bus_realize() indeed realizes all
> unrealized devices on this bus.  It carries a TODO comment claiming
> this "has to be done in common code".  No other bus realize method
> realizes its devices.
> 
> The common code in question is bus_set_realized(), which has a TODO
> comment asking for recursive realization.  It's been asking for years.
> 
> The only devices sclp_events_bus_realize() will ever realize are the
> two init_event_facility() puts there.
> 
> Simplify as follows:
> 
> * Make the devices members of the event facility instance struct, just
>   like the bus.  object_initialize_child() is simpler than
>   object_property_add_child() and object_unref().
> 
> * Realize them in the event facility realize method.
> 
> This is in line with how such things are done elsewhere.
> 
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Halil Pasic <pasic@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: qemu-s390x@nongnu.org
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  hw/s390x/event-facility.c | 59 ++++++++++++++++-----------------------
>  1 file changed, 24 insertions(+), 35 deletions(-)
> 
> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c
> index 97a4f0b1f5..1ecaa20556 100644
> --- a/hw/s390x/event-facility.c
> +++ b/hw/s390x/event-facility.c
> @@ -39,6 +39,7 @@ typedef struct SCLPEventsBus {
>  struct SCLPEventFacility {
>      SysBusDevice parent_obj;
>      SCLPEventsBus sbus;
> +    SCLPEvent quiesce, cpu_hotplug;
>      /* guest's receive mask */
>      union {
>          uint32_t receive_mask_pieces[2];
> @@ -328,34 +329,9 @@ static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb)
>  
>  #define TYPE_SCLP_EVENTS_BUS "s390-sclp-events-bus"
>  
> -static void sclp_events_bus_realize(BusState *bus, Error **errp)
> -{
> -    Error *err = NULL;
> -    BusChild *kid;
> -
> -    /* TODO: recursive realization has to be done in common code */
> -    QTAILQ_FOREACH(kid, &bus->children, sibling) {
> -        DeviceState *dev = kid->child;
> -
> -        object_property_set_bool(OBJECT(dev), true, "realized", &err);
> -        if (err) {
> -            error_propagate(errp, err);
> -            return;
> -        }
> -    }
> -}
> -
> -static void sclp_events_bus_class_init(ObjectClass *klass, void *data)
> -{
> -    BusClass *bc = BUS_CLASS(klass);
> -
> -    bc->realize = sclp_events_bus_realize;
> -}
> -
>  static const TypeInfo sclp_events_bus_info = {
>      .name = TYPE_SCLP_EVENTS_BUS,
>      .parent = TYPE_BUS,
> -    .class_init = sclp_events_bus_class_init,
>  };
>  
>  static void command_handler(SCLPEventFacility *ef, SCCB *sccb, uint64_t code)
> @@ -443,27 +419,39 @@ static void init_event_facility(Object *obj)
>  {
>      SCLPEventFacility *event_facility = EVENT_FACILITY(obj);
>      DeviceState *sdev = DEVICE(obj);
> -    Object *new;
>  
>      event_facility->mask_length = 4;
>      event_facility->allow_all_mask_sizes = true;
>      object_property_add_bool(obj, "allow_all_mask_sizes",
>                               sclp_event_get_allow_all_mask_sizes,
>                               sclp_event_set_allow_all_mask_sizes);
> +
>      /* Spawn a new bus for SCLP events */
>      qbus_create_inplace(&event_facility->sbus, sizeof(event_facility->sbus),
>                          TYPE_SCLP_EVENTS_BUS, sdev, NULL);
>  
> -    new = object_new(TYPE_SCLP_QUIESCE);
> -    object_property_add_child(obj, TYPE_SCLP_QUIESCE, new);
> -    object_unref(new);
> -    qdev_set_parent_bus(DEVICE(new), BUS(&event_facility->sbus));
> +    object_initialize_child(obj, TYPE_SCLP_QUIESCE,
> +                            &event_facility->quiesce,
> +                            TYPE_SCLP_QUIESCE);
>  
> -    new = object_new(TYPE_SCLP_CPU_HOTPLUG);
> -    object_property_add_child(obj, TYPE_SCLP_CPU_HOTPLUG, new);
> -    object_unref(new);
> -    qdev_set_parent_bus(DEVICE(new), BUS(&event_facility->sbus));
> -    /* the facility will automatically realize the devices via the bus */
> +    object_initialize_child(obj, TYPE_SCLP_CPU_HOTPLUG,
> +                            &event_facility->cpu_hotplug,
> +                            TYPE_SCLP_CPU_HOTPLUG);
> +}
> +
> +static void realize_event_facility(DeviceState *dev, Error **errp)
> +{
> +    SCLPEventFacility *event_facility = EVENT_FACILITY(dev);
> +    Error *local_err = NULL;
> +
> +    qdev_realize(DEVICE(&event_facility->quiesce),
> +                 BUS(&event_facility->sbus), &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +    qdev_realize(DEVICE(&event_facility->cpu_hotplug),
> +                 BUS(&event_facility->sbus), errp);
>  }
>  
>  static void reset_event_facility(DeviceState *dev)
> @@ -479,6 +467,7 @@ static void init_event_facility_class(ObjectClass *klass, void *data)
>      DeviceClass *dc = DEVICE_CLASS(sbdc);
>      SCLPEventFacilityClass *k = EVENT_FACILITY_CLASS(dc);
>  
> +    dc->realize = realize_event_facility;
>      dc->reset = reset_event_facility;
>      dc->vmsd = &vmstate_event_facility;
>      set_bit(DEVICE_CATEGORY_MISC, dc->categories);
> 

Think you forgot

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb