Children are automatically unparented so manually unparenting is
unnecessary.

Worse, automatic unparenting happens before the instance_finalize()
callback of the parent gets called, so object_unparent() calls in
the callback will refer to objects that are already unparented, which
is semantically incorrect.

Remove the instruction to call object_unparent(), and the exception
of the "do not call object_unparent()" rule for instance_finalize().

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
---
 docs/devel/memory.rst | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/docs/devel/memory.rst b/docs/devel/memory.rst
index 57fb2aec76e0..749f11d8a4dd 100644
--- a/docs/devel/memory.rst
+++ b/docs/devel/memory.rst
@@ -161,18 +161,11 @@ or never.
 Destruction of a memory region happens automatically when the owner
 object dies.
 
-If however the memory region is part of a dynamically allocated data
-structure, you should call object_unparent() to destroy the memory region
-before the data structure is freed.  For an example see VFIOMSIXInfo
-and VFIOQuirk in hw/vfio/pci.c.
-
 You must not destroy a memory region as long as it may be in use by a
 device or CPU.  In order to do this, as a general rule do not create or
-destroy memory regions dynamically during a device's lifetime, and only
-call object_unparent() in the memory region owner's instance_finalize
-callback.  The dynamically allocated data structure that contains the
-memory region then should obviously be freed in the instance_finalize
-callback as well.
+destroy memory regions dynamically during a device's lifetime.
+The dynamically allocated data structure that contains the
+memory region should be freed in the instance_finalize callback.
 
 If you break this rule, the following situation can happen:
 
@@ -198,9 +191,9 @@ this exception is rarely necessary, and therefore it is discouraged,
 but nevertheless it is used in a few places.
 
 For regions that "have no owner" (NULL is passed at creation time), the
-machine object is actually used as the owner.  Since instance_finalize is
-never called for the machine object, you must never call object_unparent
-on regions that have no owner, unless they are aliases or containers.
+machine object is actually used as the owner.  You must never call
+object_unparent on regions that have no owner, unless they are aliases
+or containers.
 
 
 Overlapping regions and priority

-- 
2.51.0