Re: [Qemu-devel] [PATCH v5 1/2] Add device listener interface

[Paolo Bonzini <pbonzini@redhat.com>]

On 08/12/2014 12:12, Paul Durrant wrote:
>> -----Original Message-----
>> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
>> Sent: 05 December 2014 11:45
>> To: Paul Durrant; qemu-devel@nongnu.org
>> Cc: Michael S. Tsirkin; Andreas Faerber"; Peter Crosthwaite; Igor
>> Mammedov; Markus Armbruster; Thomas Huth; Christian Borntraeger
>> Subject: Re: [PATCH v5 1/2] Add device listener interface
>>
>>
>>
>> On 05/12/2014 11:50, Paul Durrant wrote:
>>> The Xen ioreq-server API, introduced in Xen 4.5, requires that PCI device
>>> models explicitly register with Xen for config space accesses. This patch
>>> adds a listener interface into qdev-core which can be used by the Xen
>>> interface code to monitor for arrival and departure of PCI devices.
>>>
>>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>> Cc: Andreas Faerber" <afaerber@suse.de>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
>>> Cc: Igor Mammedov <imammedo@redhat.com>
>>> Cc: Markus Armbruster <armbru@redhat.com>
>>> Cc: Thomas Huth <thuth@linux.vnet.ibm.com>
>>> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
>>> ---
>>>  hw/core/qdev.c          |   53
>> +++++++++++++++++++++++++++++++++++++++++++++++
>>>  include/hw/qdev-core.h  |   10 +++++++++
>>>  include/qemu/typedefs.h |    1 +
>>>  3 files changed, 64 insertions(+)
>>>
>>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>>> index 35fd00d..76ff9ef 100644
>>> --- a/hw/core/qdev.c
>>> +++ b/hw/core/qdev.c
>>> @@ -189,6 +189,56 @@ int qdev_init(DeviceState *dev)
>>>      return 0;
>>>  }
>>>
>>> +static QTAILQ_HEAD(device_listeners, DeviceListener) device_listeners
>>> +    = QTAILQ_HEAD_INITIALIZER(device_listeners);
>>> +
>>> +enum ListenerDirection { Forward, Reverse };
>>> +
>>> +#define DEVICE_LISTENER_CALL(_callback, _direction, _args...)     \
>>> +    do {                                                          \
>>> +        DeviceListener *_listener;                                \
>>> +                                                                  \
>>> +        switch (_direction) {                                     \
>>> +        case Forward:                                             \
>>> +            QTAILQ_FOREACH(_listener, &device_listeners, link) {  \
>>> +                if (_listener->_callback) {                       \
>>> +                    _listener->_callback(_listener, ##_args);     \
>>> +                }                                                 \
>>> +            }                                                     \
>>> +            break;                                                \
>>> +        case Reverse:                                             \
>>> +            QTAILQ_FOREACH_REVERSE(_listener, &device_listeners,  \
>>> +                                   device_listeners, link) {      \
>>> +                if (_listener->_callback) {                       \
>>> +                    _listener->_callback(_listener, ##_args);     \
>>> +                }                                                 \
>>> +            }                                                     \
>>> +            break;                                                \
>>> +        default:                                                  \
>>> +            abort();                                              \
>>> +        }                                                         \
>>> +    } while (0)
>>> +
>>> +static int device_listener_add(DeviceState *dev, void *opaque)
>>> +{
>>> +    DEVICE_LISTENER_CALL(realize, Forward, dev);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +void device_listener_register(DeviceListener *listener)
>>> +{
>>> +    QTAILQ_INSERT_TAIL(&device_listeners, listener, link);
>>> +
>>> +    qbus_walk_children(sysbus_get_default(), NULL, NULL,
>> device_listener_add,
>>> +                       NULL, NULL);
>>> +}
>>> +
>>> +void device_listener_unregister(DeviceListener *listener)
>>> +{
>>> +    QTAILQ_REMOVE(&device_listeners, listener, link);
>>> +}
>>> +
>>>  static void device_realize(DeviceState *dev, Error **errp)
>>>  {
>>>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
>>> @@ -994,6 +1044,8 @@ static void device_set_realized(Object *obj, bool
>> value, Error **errp)
>>>              goto fail;
>>>          }
>>>
>>> +        DEVICE_LISTENER_CALL(realize, Forward, dev);
>>> +
>>>          hotplug_ctrl = qdev_get_hotplug_handler(dev);
>>>          if (hotplug_ctrl) {
>>>              hotplug_handler_plug(hotplug_ctrl, dev, &local_err);
>>> @@ -1035,6 +1087,7 @@ static void device_set_realized(Object *obj, bool
>> value, Error **errp)
>>>              dc->unrealize(dev, local_errp);
>>>          }
>>>          dev->pending_deleted_event = true;
>>> +        DEVICE_LISTENER_CALL(unrealize, Reverse, dev);
>>>      }
>>>
>>>      if (local_err != NULL) {
>>> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
>>> index 589bbe7..15a226f 100644
>>> --- a/include/hw/qdev-core.h
>>> +++ b/include/hw/qdev-core.h
>>> @@ -165,6 +165,12 @@ struct DeviceState {
>>>      int alias_required_for_version;
>>>  };
>>>
>>> +struct DeviceListener {
>>> +    void (*realize)(DeviceListener *listener, DeviceState *dev);
>>> +    void (*unrealize)(DeviceListener *listener, DeviceState *dev);
>>> +    QTAILQ_ENTRY(DeviceListener) link;
>>> +};
>>> +
>>>  #define TYPE_BUS "bus"
>>>  #define BUS(obj) OBJECT_CHECK(BusState, (obj), TYPE_BUS)
>>>  #define BUS_CLASS(klass) OBJECT_CLASS_CHECK(BusClass, (klass),
>> TYPE_BUS)
>>> @@ -376,4 +382,8 @@ static inline bool qbus_is_hotpluggable(BusState
>> *bus)
>>>  {
>>>     return bus->hotplug_handler;
>>>  }
>>> +
>>> +void device_listener_register(DeviceListener *listener);
>>> +void device_listener_unregister(DeviceListener *listener);
>>> +
>>>  #endif
>>> diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
>>> index 3475177..4bb4938 100644
>>> --- a/include/qemu/typedefs.h
>>> +++ b/include/qemu/typedefs.h
>>> @@ -20,6 +20,7 @@ typedef struct Property Property;
>>>  typedef struct PropertyInfo PropertyInfo;
>>>  typedef struct CompatProperty CompatProperty;
>>>  typedef struct DeviceState DeviceState;
>>> +typedef struct DeviceListener DeviceListener;
>>>  typedef struct BusState BusState;
>>>  typedef struct BusClass BusClass;
>>>
>>>
>>
>> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
>>
> 
> Great. Thanks for that. All I need now is an ack on this from a maintainer.

I think my reviewed-by is pretty close to an Ack.

Stefano, feel free to pick this patch up together with 2/2.

Paolo