On Fri, Aug 24, 2012 at 10:42 PM, Paolo Bonzini <pbonz...@redhat.com> wrote:
> Il 24/08/2012 11:49, Liu Ping Fan ha scritto:
>> With this patch, we can protect PCIIDEState from disappearing during
>> mmio-dispatch hold the IDEBus->ref.
>
> I don't see why MMIO dispatch should hold the IDEBus ref rather than the
> PCIIDEState.
>
When transfer memory_region_init_io() 3rd para from void* opaque to
Object* obj, the obj : opaque is not neccessary 1:1 map. For such
situation, in order to let MemoryRegionOps tell between them, we
should pass PCIIDEState->bus[0], bus[1] separately.
> In the case of the PIIX, the BARs are set up by the PCIIDEState in
> bmdma_setup_bar (called by bmdma_setup_bar).
>
Supposing we have convert PCIIDEState->bmdma[0]/[1] to Object. And in
mmio-dispatch, object_ref will impose on bmdma[0/[1], but this can not
prevent PCIIDEState->refcnt=0, and then the whole object disappear!
Thanks and regards,
pingfan
> Also, containment may happen just as well for devices, not buses. Why
> isn't it a problem in that case? It looks like you're papering over a
> different bug.
>
> Paolo
>
>> And the ref circle has been broken when calling qdev_delete_subtree().
>>
>> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
>> ---
>> hw/qdev.c | 2 ++
>> hw/qdev.h | 1 +
>> 2 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/hw/qdev.c b/hw/qdev.c
>> index e2339a1..b09ebbf 100644
>> --- a/hw/qdev.c
>> +++ b/hw/qdev.c
>> @@ -510,6 +510,8 @@ void qbus_create_inplace(BusState *bus, const char
>> *typename,
>> {
>> object_initialize(bus, typename);
>>
>> + bus->overlap = parent;
>> + object_ref(OBJECT(bus->overlap));
>> bus->parent = parent;
>> bus->name = name ? g_strdup(name) : NULL;
>> qbus_realize(bus);
>> diff --git a/hw/qdev.h b/hw/qdev.h
>> index 182cfa5..9bc5783 100644
>> --- a/hw/qdev.h
>> +++ b/hw/qdev.h
>> @@ -117,6 +117,7 @@ struct BusState {
>> int allow_hotplug;
>> bool qom_allocated;
>> bool glib_allocated;
>> + DeviceState *overlap;
>> int max_index;
>> QTAILQ_HEAD(ChildrenHead, BusChild) children;
>> QLIST_ENTRY(BusState) sibling;
>> -- 1.7.4.4
>
