[RFC PATCH v2 122/137] system: Parent per-MR helper objects under their owner

RamBlockAttributes and MemoryRegionPortioList objects are long-lived
helpers whose lifetime is already tied to a MemoryRegion or its owner.
Give each a canonical path under that owner instead of leaving them
as floating refcounted objects:

  <mr-path>/attributes           (RamBlockAttributes)
  <owner-path>/portio-list[N]    (MemoryRegionPortioList)

The destroy paths switch from object_unref() to object_unparent()
now that the parent holds the reference.

RamDiscardManager is deliberately left as-is: it is unref'd from
memory_region_finalize() itself, so making it a child<> of the MR
would introduce a use-after-free during MR teardown.  It can move
under a different owner in a follow-up once the RDM lifecycle is
untangled from MR finalize.

AI-used-for: code (refactoring)
Signed-off-by: Alexander Graf <[email protected]>
---
 system/ioport.c               | 5 +++--
 system/ram-block-attributes.c | 7 ++++---
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/system/ioport.c b/system/ioport.c
index 0415b3cd60..77ab77d7be 100644
--- a/system/ioport.c
+++ b/system/ioport.c
@@ -145,7 +145,7 @@ void portio_list_destroy(PortioList *piolist)
     for (i = 0; i < piolist->nr; ++i) {
         mrpio = container_of(piolist->regions[i], MemoryRegionPortioList, mr);
         object_unparent(OBJECT(&mrpio->mr));
-        object_unref(mrpio);
+        object_unparent(OBJECT(mrpio));
     }
     g_free(piolist->regions);
 }
@@ -228,7 +228,8 @@ static void portio_list_add_1(PortioList *piolist,
 
     /* Copy the sub-list and null-terminate it.  */
     mrpio = MEMORY_REGION_PORTIO_LIST(
-                object_new(TYPE_MEMORY_REGION_PORTIO_LIST));
+                object_new_child(piolist->owner, "portio-list[*]",
+                                 TYPE_MEMORY_REGION_PORTIO_LIST));
     mrpio->portio_opaque = piolist->opaque;
     mrpio->ports = g_new0(MemoryRegionPortio, count + 1);
     memcpy(mrpio->ports, pio_init, sizeof(MemoryRegionPortio) * count);
diff --git a/system/ram-block-attributes.c b/system/ram-block-attributes.c
index 59ec7a28eb..0967bed6d3 100644
--- a/system/ram-block-attributes.c
+++ b/system/ram-block-attributes.c
@@ -182,12 +182,13 @@ RamBlockAttributes *ram_block_attributes_create(RAMBlock *ram_block)
     RamBlockAttributes *attr;
     MemoryRegion *mr = ram_block->mr;
 
-    attr = RAM_BLOCK_ATTRIBUTES(object_new(TYPE_RAM_BLOCK_ATTRIBUTES));
+    attr = RAM_BLOCK_ATTRIBUTES(object_new_child(OBJECT(mr), "attributes",
+                                                 TYPE_RAM_BLOCK_ATTRIBUTES));
 
     attr->ram_block = ram_block;
 
     if (memory_region_add_ram_discard_source(mr, RAM_DISCARD_SOURCE(attr))) {
-        object_unref(OBJECT(attr));
+        object_unparent(OBJECT(attr));
         return NULL;
     }
     attr->bitmap_size = DIV_ROUND_UP(int128_get64(mr->size), block_size);
@@ -202,7 +203,7 @@ void ram_block_attributes_destroy(RamBlockAttributes *attr)
 
     g_free(attr->bitmap);
     memory_region_del_ram_discard_source(attr->ram_block->mr, RAM_DISCARD_SOURCE(attr));
-    object_unref(OBJECT(attr));
+    object_unparent(OBJECT(attr));
 }
 
 static void ram_block_attributes_init(Object *obj)
-- 
2.47.1