Re: [Qemu-devel] [PATCH] qom: removal of link property need to release its target

[Paolo Bonzini <pbonzini@redhat.com>]

Il 22/08/2012 23:41, Anthony Liguori ha scritto:
> 
> (1) should drop the floating reference and the reference held by the
> container.  That's what I meant by calling object_unparent in
> qmp_device_del.
> 
> (2) should simply remove the device from the bus (further releasing a
> reference).
> 
> (3) would happen automatically from (1) and (2) if they were called in
> that order.
> 
> If the guest instantiates a remove on it's own, the device would be
> disconnected from the bus (functionally unplugged) but still in the
> container so it would *not* go away.
> 
> I think this is desirable behavior.

It may be (I'm not sure it is desirable for HMP), but it's also
backwards-incompatible.  Right now, an unrequested guest-initiated
remove causes the device to disappear in "info qtree" too.  So, for
backwards-compatibility we need to keep using object_delete after
setting the parent bus to NULL.

WRT adding the unparent *also* in qmp_device_del, that prevents you from
later doing a surprise removal via the monitor, because you don't have
anymore a way to refer the device.  I'm also worried of what happens if
an object loses its canonical path in the middle of its life...

I'm not sure object_unparent should be extern, even.

Paolo