[Qemu-devel] [PATCH 15/18] qom: optimize qdev_get_canonical_path using a parent link

[Anthony Liguori]

The full tree search was a bit unreasonable.

Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
---
 hw/qdev.c |   60 +++++++++++++++++++++++++++---------------------------------
 hw/qdev.h |    4 ++++
 2 files changed, 31 insertions(+), 33 deletions(-)

diff --git a/hw/qdev.c b/hw/qdev.c
index b944108..7da7196 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -1210,6 +1210,9 @@ void qdev_property_add_child(DeviceState *dev, const char 
*name,
     qdev_property_add(dev, name, type, qdev_get_child_property,
                       NULL, NULL, child, errp);
 
+    g_assert(child->parent == NULL);
+    child->parent = dev;
+
     g_free(type);
 }
 
@@ -1282,48 +1285,39 @@ void qdev_property_add_link(DeviceState *dev, const 
char *name,
     g_free(full_type);
 }
 
-static gchar *qdev_get_path_in(DeviceState *parent, DeviceState *dev)
+gchar *qdev_get_canonical_path(DeviceState *dev)
 {
-    GSList *i;
+    DeviceState *root = qdev_get_root();
+    char *newpath = NULL, *path = NULL;
 
-    if (parent == dev) {
-        return g_strdup("");
-    }
-
-    for (i = parent->properties; i; i = i->next) {
-        DeviceProperty *prop = i->data;
-        gchar *subpath;
-
-        if (!strstart(prop->type, "child<", NULL)) {
-            continue;
-        }
+    while (dev != root) {
+        GSList *i;
 
-        /* Check to see if the device is one of parent's children */
-        if (prop->opaque == dev) {
-            return g_strdup(prop->name);
-        }
+        g_assert(dev->parent != NULL);
 
-        /* Check to see if the device is a child of our child */
-        subpath = qdev_get_path_in(prop->opaque, dev);
-        if (subpath) {
-            gchar *path;
+        for (i = dev->parent->properties; i; i = i->next) {
+            DeviceProperty *prop = i->data;
 
-            path = g_strdup_printf("%s/%s", prop->name, subpath);
-            g_free(subpath);
+            if (!strstart(prop->type, "child<", NULL)) {
+                continue;
+            }
 
-            return path;
+            if (prop->opaque == dev) {
+                if (path) {
+                    newpath = g_strdup_printf("%s/%s", prop->name, path);
+                    g_free(path);
+                    path = newpath;
+                } else {
+                    path = g_strdup(prop->name);
+                }
+                break;
+            }
         }
-    }
 
-    return NULL;
-}
+        g_assert(i != NULL);
 
-gchar *qdev_get_canonical_path(DeviceState *dev)
-{
-    gchar *path, *newpath;
-
-    path = qdev_get_path_in(qdev_get_root(), dev);
-    g_assert(path != NULL);
+        dev = dev->parent;
+    }
 
     newpath = g_strdup_printf("/%s", path);
     g_free(path);
diff --git a/hw/qdev.h b/hw/qdev.h
index e8c9e76..8eb7ce1 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -83,6 +83,10 @@ struct DeviceState {
     int instance_id_alias;
     int alias_required_for_version;
     GSList *properties;
+
+    /* Do not, under any circumstance, use this parent link below anywhere
+     * outside of qdev.c.  You have been warned. */
+    DeviceState *parent;
 };
 
 typedef void (*bus_dev_printfn)(Monitor *mon, DeviceState *dev, int indent);
-- 
1.7.4.1