On Mon, May 14, 2018 at 12:00:08PM +0200, David Hildenbrand wrote:
> From: Igor Mammedov <imamm...@redhat.com>
>
> it will allow to return another hotplug handler than the default
> one for a specific bus based device type. Which is needed to handle
> non trivial plug/unplug sequences that need the access to resources
> configured outside of bus where device is attached.
>
> That will allow for returned hotplug handler to orchestrate wiring
> in arbitrary order, by chaining other hotplug handlers when
> it's needed.
>
> PS:
> It could be used for hybrid virtio-mem and virtio-pmem devices
> where it will return machine as hotplug handler which will do
> necessary wiring at machine level and then pass control down
> the chain to bus specific hotplug handler.
>
> Example of top level hotplug handler override and custom plug sequence:
>
> some_machine_get_hotplug_handler(machine){
> if (object_dynamic_cast(OBJECT(dev), TYPE_SOME_BUS_DEVICE)) {
> return HOTPLUG_HANDLER(machine);
> }
> return NULL;
> }
>
> some_machine_device_plug(hotplug_dev, dev) {
> if (object_dynamic_cast(OBJECT(dev), TYPE_SOME_BUS_DEVICE)) {
> /* do machine specific initialization */
> some_machine_init_special_device(dev)
>
> /* pass control to bus specific handler */
> hotplug_handler_plug(dev->parent_bus->hotplug_handler, dev)
> }
> }
Hi, David.
I might be misreading, but isn't it more like the following?
some_machine_device_plug(hotplug_dev, dev) {
if (object_dynamic_cast(OBJECT(dev), TYPE_SOME_BUS_DEVICE)) {
/* do machine specific initialization */
some_machine_init_special_device(dev)
} else {
/* pass control to bus specific handler */
hotplug_handler_plug(dev->parent_bus->hotplug_handler, dev)
}
}
> Signed-off-by: Igor Mammedov <imamm...@redhat.com>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
> hw/core/qdev.c | 6 ++----
> include/hw/qdev-core.h | 11 +++++++++++
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index f6f92473b8..885286f579 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -261,12 +261,10 @@ HotplugHandler
> *qdev_get_machine_hotplug_handler(DeviceState *dev)
>
> HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
> {
> - HotplugHandler *hotplug_ctrl;
> + HotplugHandler *hotplug_ctrl = qdev_get_machine_hotplug_handler(dev);
>
> - if (dev->parent_bus && dev->parent_bus->hotplug_handler) {
> + if (hotplug_ctrl == NULL && dev->parent_bus) {
> hotplug_ctrl = dev->parent_bus->hotplug_handler;
> - } else {
> - hotplug_ctrl = qdev_get_machine_hotplug_handler(dev);
> }
> return hotplug_ctrl;
> }
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index 9453588160..e6a8eca558 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -286,6 +286,17 @@ void qdev_init_nofail(DeviceState *dev);
> void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
> int required_for_version);
> HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev);
> +/**
> + * qdev_get_hotplug_handler: Get handler responsible for device wiring
> + *
> + * Find HOTPLUG_HANDLER for @dev that provides [pre|un]plug callbacks for it.
> + *
> + * Note: in case @dev has a parent bus, it will be returned as handler unless
> + * machine handler overrides it.
> + *
> + * Returns: pointer to object that implements TYPE_HOTPLUG_HANDLER interface
> + * or NULL if there aren't any.
> + */
> HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev);
> void qdev_unplug(DeviceState *dev, Error **errp);
> void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
> --
> 2.14.3
>
>
--
Murilo
