[Qemu-devel] [PATCH 05/11] memory: add ref/unref

[Paolo Bonzini <pbonzini@redhat.com>]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/exec/memory.h | 30 ++++++++++++++++++++++++++++++
 memory.c              | 14 ++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 763297e..c842d48 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -270,6 +270,36 @@ void memory_region_init(MemoryRegion *mr,
                         struct Object *owner,
                         const char *name,
                         uint64_t size);
+
+/**
+ * memory_region_ref: Add 1 to a memory region's reference count
+ *
+ * Whenever memory regions are accessed outside the BQL, they need to be
+ * preserved against hot-unplug.  MemoryRegions actually do not have their
+ * own reference count; they piggyback on a QOM object, their "owner".
+ * This function adds a reference to the owner.
+ *
+ * All MemoryRegions must have an owner if they can disappear, even if the
+ * device they belong to operates exclusively under the BQL.  This is because
+ * the region could be returned at any time by memory_region_find, and this
+ * is usually under guest control.
+ *
+ * @mr: the #MemoryRegion
+ */
+void memory_region_ref(MemoryRegion *mr);
+
+/**
+ * memory_region_unref: Remove 1 to a memory region's reference count
+ *
+ * Whenever memory regions are accessed outside the BQL, they need to be
+ * preserved against hot-unplug.  MemoryRegions actually do not have their
+ * own reference count; they piggyback on a QOM object, their "owner".
+ * This function removes a reference to the owner and possibly destroys it.
+ *
+ * @mr: the #MemoryRegion
+ */
+void memory_region_unref(MemoryRegion *mr);
+
 /**
  * memory_region_init_io: Initialize an I/O memory region.
  *
diff --git a/memory.c b/memory.c
index 61b3f25..b74078c 100644
--- a/memory.c
+++ b/memory.c
@@ -1105,6 +1105,20 @@ Object *memory_region_owner(MemoryRegion *mr)
     return mr->owner;
 }
 
+void memory_region_ref(MemoryRegion *mr)
+{
+    if (mr && mr->owner) {
+        object_ref(mr->owner);
+    }
+}
+
+void memory_region_unref(MemoryRegion *mr)
+{
+    if (mr && mr->owner) {
+        object_unref(mr->owner);
+    }
+}
+
 uint64_t memory_region_size(MemoryRegion *mr)
 {
     if (int128_eq(mr->size, int128_2_64())) {
-- 
1.8.1.4