Re: [Qemu-arm] [Qemu-devel] [PATCH v6 1/6] qdev: get_child_bus(): Use QOM lookup if available

[Peter Crosthwaite]

On Wed, Jan 6, 2016 at 4:18 PM, Alistair Francis
<address@hidden> wrote:
> On Sat, Dec 19, 2015 at 9:43 PM, Peter Crosthwaite
> <address@hidden> wrote:
>> qbus_realize() adds busses as a QOM child of the device in addition to
>> adding it to the qdev bus list. Change get_child_bus() to use the QOM
>> child if it is available. This takes priority over the bus-list, but
>> the child object is checked for type correctness.
>
> This doesn't cause problems for anything else? Is there anything else
> with the same name or something where this causes conflicts?
>

Not that I know of, I'm just being defensive as it is core code. I
suspect that that ignored failure path on the child setter is
incorrect but I can't prove it beyond all doubt.

Regards,
Peter

> Thanks,
>
> Alistair
>
>>
>> This prepares support for aliasing of buses. The use case is SoCs,
>> where a SoC container needs to present buses to the board level, but
>> the buses are implemented by controller IP we already model as self
>> contained qbus-containing devices.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> ---
>> Currently qbus_realize() ignores errors from object_property_add_child,
>> so it is hard to guarantee that the QOM linkage is reliable. If it were
>> the case that that object_property_add_child was supposed to be error
>> asserting, we could remove the old bus-list strcmp iterator altogether.
>>
>>  hw/core/qdev.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>> index b3ad467..c96c464 100644
>> --- a/hw/core/qdev.c
>> +++ b/hw/core/qdev.c
>> @@ -581,6 +581,12 @@ void qdev_pass_gpios(DeviceState *dev, DeviceState 
>> *container,
>>  BusState *qdev_get_child_bus(DeviceState *dev, const char *name)
>>  {
>>      BusState *bus;
>> +    Object *child = object_resolve_path_component(OBJECT(dev), name);
>> +
>> +    bus = (BusState *)object_dynamic_cast(child, TYPE_BUS);
>> +    if (bus) {
>> +        return bus;
>> +    }
>>
>>      QLIST_FOREACH(bus, &dev->child_bus, sibling) {
>>          if (strcmp(name, bus->name) == 0) {
>> --
>> 1.9.1
>>
>>