Am 25.01.2013 12:46, schrieb Paolo Bonzini:
> A device will never be finalized as long as it has a reference from
> other devices that sit on its buses. To ensure that the references
> go away, deassociate a bus from its children in the unparent callback
> for the bus.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
To help me and others understand this, the children often have
back-references to the bus blocking the bus' finalization? Is that what
you're tackling here?
Remind me, when exactly would the unparent hook being called in case of
a PCI host bridge? prep_pci create a PCI dev to represent itself, 1 ref,
and puts it on the bus. At some point, the bus is unparented (removed
from, e.g., /machine/unassigned, I interpret) and with this patch the
children are unparented and unref'ed. That would still leave the
original object_initialize() ref behind, so that I would still need to
unref it in a finalizefn, no?
Regards,
Andreas
> ---
> hw/qdev.c | 37 +++++++++++++++++++++++++------------
> 1 file changed, 25 insertions(+), 12 deletions(-)
>
> diff --git a/hw/qdev.c b/hw/qdev.c
> index 78eedf0..364386d 100644
> --- a/hw/qdev.c
> +++ b/hw/qdev.c
> @@ -433,6 +433,25 @@ static void qbus_realize(BusState *bus, DeviceState
> *parent, const char *name)
> }
> }
>
> +static void bus_unparent(Object *obj)
> +{
> + BusState *bus = BUS(obj);
> + BusChild *kid;
> +
> + while ((kid = QTAILQ_FIRST(&bus->children)) != NULL) {
> + DeviceState *dev = kid->child;
> + qdev_free(dev);
> + }
> + if (bus->parent) {
> + QLIST_REMOVE(bus, sibling);
> + bus->parent->num_child_bus--;
> + bus->parent = NULL;
> + } else {
> + assert(bus != sysbus_get_default()); /* main_system_bus is never
> freed */
> + qemu_unregister_reset(qbus_reset_all_fn, bus);
> + }
> +}
> +
> void qbus_create_inplace(BusState *bus, const char *typename,
> DeviceState *parent, const char *name)
> {
> @@ -805,22 +824,15 @@ static void qbus_initfn(Object *obj)
> QTAILQ_INIT(&bus->children);
> }
>
> +static void bus_class_init(ObjectClass *class, void *data)
> +{
> + class->unparent = bus_unparent;
> +}
> +
> static void qbus_finalize(Object *obj)
> {
> BusState *bus = BUS(obj);
> - BusChild *kid;
>
> - while ((kid = QTAILQ_FIRST(&bus->children)) != NULL) {
> - DeviceState *dev = kid->child;
> - qdev_free(dev);
> - }
> - if (bus->parent) {
> - QLIST_REMOVE(bus, sibling);
> - bus->parent->num_child_bus--;
> - } else {
> - assert(bus != sysbus_get_default()); /* main_system_bus is never
> freed */
> - qemu_unregister_reset(qbus_reset_all_fn, bus);
> - }
> g_free((char *)bus->name);
> }
>
> @@ -832,6 +844,7 @@ static const TypeInfo bus_info = {
> .class_size = sizeof(BusClass),
> .instance_init = qbus_initfn,
> .instance_finalize = qbus_finalize,
> + .class_init = bus_class_init,
> };
>
> static void qdev_register_types(void)
>
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