Re: [Qemu-devel] [PATCH 05/11] qdev: add "hotplugable" property to Device

[Paolo Bonzini <pbonzini@redhat.com>]

Il 11/12/2013 02:01, Igor Mammedov ha scritto:
> Currently it's possible to make PCIDevice not hotplugable by using
> no_hotplug field of PCIDeviceClass. However it limits this
> only to PCI devices and prevents from generalizing hotplug code.
> 
> So add similar field to DeviceClass so it could be reused with other
> Devices and would allow to replace PCI specific hotplug callbacks
> with generic implementation.
> 
> In addition expose field as "hotplugable" readonly property, to make
> it possible to get it via QOM interface.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  hw/core/qdev.c         |    8 ++++++++
>  include/hw/qdev-core.h |    3 +++
>  2 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 25c2d2c..1b1a684 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -719,6 +719,12 @@ static void device_set_realized(Object *obj, bool value, Error **err)
>      dev->realized = value;
>  }
>  
> +static bool device_get_hotplugable(Object *obj, Error **err)
> +{
> +    DeviceClass *dc = DEVICE_GET_CLASS(obj);
> +    return dc->hotplugable;
> +}
> +
>  static void device_initfn(Object *obj)
>  {
>      DeviceState *dev = DEVICE(obj);
> @@ -736,6 +742,8 @@ static void device_initfn(Object *obj)
>  
>      object_property_add_bool(obj, "realized",
>                               device_get_realized, device_set_realized, NULL);
> +    object_property_add_bool(obj, "hotplugable",
> +                             device_get_hotplugable, NULL, NULL);
>  
>      class = object_get_class(OBJECT(dev));
>      do {
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index 684a5da..5d4a9c8 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -50,6 +50,8 @@ struct VMStateDescription;
>   * is changed to %true. Deprecated, new types inheriting directly from
>   * TYPE_DEVICE should use @realize instead, new leaf types should consult
>   * their respective parent type.
> + * @hotplugable: booleean indicating if #DeviceClass is hotplugable, available
> + * as readonly "hotplugable" property of #DeviceState instance
>   *
>   * # Realization #
>   * Devices are constructed in two stages,
> @@ -99,6 +101,7 @@ typedef struct DeviceClass {
>      const char *desc;
>      Property *props;
>      int no_user;
> +    bool hotplugable;
>  
>      /* callbacks */
>      void (*reset)(DeviceState *dev);
> 

Does this patch break SCSI and virtio-serial hotplug?

Perhaps you could initialize dc->hotpluggable to true, and return
"dc->hotplugable && device->parent_bus->allow_hotplug" from the property
getter?  Or just set the class to true in the common superclasses of all
buses that support hotplug, but that's a bit harder.

Paolo