On Thu, Jul 12, 2018 at 06:55:20PM +0200, Thomas Huth wrote: > On 12.07.2018 18:52, Eduardo Habkost wrote: > > On Thu, Jul 12, 2018 at 05:30:59PM +0200, Thomas Huth wrote: > >> A lot of code is using the object_initialize() function followed by a call > >> to > >> object_property_add_child() to add the newly initialized object as a child > >> of > >> the current object. Both functions increase the reference counter of the > >> new > >> object, but many spots that call these two functions then forget to drop > >> one > >> of the superfluous references. So the newly created object is often not > >> cleaned > >> up correctly when the parent is destroyed. In the worst case, this can > >> cause > >> crashes, e.g. because device objects are not correctly removed from their > >> parent_bus. > >> Since this is a common pattern between many code spots, let's introdcue a > >> new function that takes care of calling all three required initialization > >> functions, first object_initialize(), then object_property_add_child() and > >> finally object_unref(). > >> > >> Signed-off-by: Thomas Huth <th...@redhat.com> > >> --- > >> include/qom/object.h | 19 +++++++++++++++++++ > >> qom/object.c | 14 ++++++++++++++ > >> 2 files changed, 33 insertions(+) > >> > >> diff --git a/include/qom/object.h b/include/qom/object.h > >> index f3d2308..c1b254c 100644 > >> --- a/include/qom/object.h > >> +++ b/include/qom/object.h > >> @@ -749,6 +749,25 @@ int object_set_propv(Object *obj, > >> void object_initialize(void *obj, size_t size, const char *typename); > >> > >> /** > >> + * object_initialize_as_child: > >> + * @parentobj: The parent object to add a property to > >> + * @propname: The name of the property > >> + * @childobj: A pointer to the memory to be used for the object. > >> + * @size: The maximum size available at @obj for the object. > >> + * @type: The name of the type of the object to instantiate. > >> + * @errp: If an error occurs, a pointer to an area to store the area > >> + * > >> + * This function will initialize an object. The memory for the object > >> should > >> + * have already been allocated. The object will then be added as child > >> property > >> + * to a parent with object_property_add_child() function. The returned > >> object > >> + * has a reference count of 1, and will be finalized when the last > >> reference is > >> + * dropped. > >> + */ > >> +void object_initialize_as_child(Object *parentobj, const char *propname, > >> + void *childobj, size_t size, const char > >> *type, > >> + Error **errp); > > > > Why did you use void* instead of Object*? > > That's the same what object_initialize() is doing (see above). Otherwise > all the callers have to cast their pointers with OBJECT() first.
Why wouldn't the same argument apply to every single function that takes Object* as argument? Why the OBJECT macro exists? -- Eduardo
