[Qemu-devel] [PATCH v2 3/6] memory: add ref/unref interface for MemroyRegionOps

[Liu Ping Fan <qemulist@gmail.com>]

From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>

This pair of interface are optinal, except for those device which is
used outside the biglock's protection for hot unplug. Currently,
HostMem used by virtio-blk dataplane is outside biglock, so the RAM
device should implement this.

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
---
 include/exec/memory.h |   10 ++++++++++
 memory.c              |   18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 2761668..edeb480 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -54,6 +54,12 @@ struct MemoryRegionIORange {
  * Memory region callbacks
  */
 struct MemoryRegionOps {
+
+    /* ref/unref pair is optional;  ref.
+     * inc refcnt of object who store MemoryRegion
+     */
+    void (*ref)(void);
+    void (*unref)(void);
     /* Read from the memory region. @addr is relative to @mr; @size is
      * in bytes. */
     uint64_t (*read)(void *opaque,
@@ -223,6 +229,10 @@ struct MemoryListener {
     QTAILQ_ENTRY(MemoryListener) link;
 };
 
+/**/
+bool memory_region_ref(MemoryRegion *mr);
+bool memory_region_unref(MemoryRegion *mr);
+
 /**
  * memory_region_init: Initialize a memory region
  *
diff --git a/memory.c b/memory.c
index 75ca281..c29998d 100644
--- a/memory.c
+++ b/memory.c
@@ -786,6 +786,24 @@ static bool memory_region_wrong_endianness(MemoryRegion *mr)
 #endif
 }
 
+bool memory_region_ref(MemoryRegion *mr)
+{
+    if (mr->ops && mr->ops->ref) {
+        mr->ops->ref();
+        return true;
+    }
+    return false;
+}
+
+bool memory_region_unref(MemoryRegion *mr)
+{
+    if (mr->ops && mr->ops->unref) {
+        mr->ops->unref();
+        return true;
+    }
+    return false;
+}
+
 void memory_region_init(MemoryRegion *mr,
                         const char *name,
                         uint64_t size)
-- 
1.7.4.4