Re: QOM address space handling

[Eduardo Habkost <ehabkost@redhat.com>]

On Sun, Dec 20, 2020 at 10:25:25AM +0100, Paolo Bonzini wrote:
> On 18/12/20 23:32, Eduardo Habkost wrote:
> > Who owns the FlatView reference, exactly?
> 
> The AddressSpace.  The device creates the AddressSpace, which holds a
> reference to the MemoryRegion through FlatView and AddressSpaceDispatch,
> which holds a reference to the device.
> 
> By destroying the address space that it created, the device can break the
> reference loop.
> 
> > If the FlatView reference is owned by the MemoryRegion, we have a
> > reference loop: the device holds a reference to the MemoryRegion,
> > which owns the FlatView, which holds a reference to the device.
> > In this case, who owns the reference loop and is responsible for
> > breaking it?
> 
> The reference loop is owned by the device, which breaks it through unrealize
> (called by unparent).
> 
> instance_finalize by definition cannot break reference loops, so this means
> that my suggestion of using address_space_init in instance_init was wrong.

Once we fix that, I suggest we add an assertion to make it
illegal to call object_ref() on an object during instance_init.

Do we know how many address_space_init() calls in instance_init
we have today?

-- 
Eduardo