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Date: Fri, 24 Aug 2012 16:42:57 +0200
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Subject: Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life
	cycle problem
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To: Liu Ping Fan <qemulist@gmail.com>
Cc: Liu Ping Fan <pingfank@linux.vnet.ibm.com>, qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>, Avi Kivity <avi@redhat.com>

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.

In the case of the PIIX, the BARs are set up by the PCIIDEState in
bmdma_setup_bar (called by bmdma_setup_bar).

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 <pingfank@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