If the properties are already in the live tree then there is no
need to create a changeset entry to add them since they must
have the same value.  This reduces the memory used by the
changeset and eliminates a possible memory leak.  This is
verified by 12 fewer warnings during the devicetree unittest,
as the possible memory leak warnings about #address-cells and

Signed-off-by: Frank Rowand <redacted>
---
 drivers/of/overlay.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 29c33a5c533f..e6fb3ffe9d93 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c

@@ -287,7 +287,12 @@ static struct property *dup_and_fixup_symbol_prop(
  * @target may be either in the live devicetree or in a new subtree that
  * is contained in the changeset.
  *
- * Some special properties are not updated (no error returned).
+ * Some special properties are not added or updated (no error returned):
+ * "name", "phandle", "linux,phandle".
+ *
+ * Properties "#address-cells" and "#size-cells" are not updated if they
+ * are already in the live tree, but if present in the live tree, the values
+ * in the overlay must match the values in the live tree.
  *
  * Update of property in symbols node is not allowed.
  *

@@ -300,6 +305,7 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
 {
        struct property *new_prop = NULL, *prop;
        int ret = 0;
+       bool check_for_non_overlay_node = false;

        if (!of_prop_cmp(overlay_prop->name, "name") ||
            !of_prop_cmp(overlay_prop->name, "phandle") ||

@@ -322,13 +328,39 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
        if (!new_prop)
                return -ENOMEM;

-       if (!prop)
+       if (!prop) {
+
+               check_for_non_overlay_node = true;
                ret = of_changeset_add_property(&ovcs->cset, target->np,
                                                new_prop);
-       else
+
+       } else if (!of_prop_cmp(prop->name, "#address-cells")) {
+
+               if (prop->length != 4 || new_prop->length != 4 ||
+                   *(u32 *)prop->value != *(u32 *)new_prop->value)
+                       pr_err("ERROR: overlay and/or live tree #address-cells invalid in node %pOF\n",
+                              target->np);
+
+       } else if (!of_prop_cmp(prop->name, "#size-cells")) {
+
+               if (prop->length != 4 || new_prop->length != 4 ||
+                   *(u32 *)prop->value != *(u32 *)new_prop->value)
+                       pr_err("ERROR: overlay and/or live tree #size-cells invalid in node %pOF\n",
+                              target->np);
+
+       } else {
+
+               check_for_non_overlay_node = true;
                ret = of_changeset_update_property(&ovcs->cset, target->np,
                                                   new_prop);

+       }
+
+       if (check_for_non_overlay_node &&
+           !of_node_check_flag(target->np, OF_OVERLAY))
+               pr_err("WARNING: %s(), memory leak will occur if overlay removed.  Property: %pOF/%s\n",
+                      __func__, target->np, new_prop->name);
+
        if (ret) {
                kfree(new_prop->name);
                kfree(new_prop->value);
--

Frank Rowand [off-list ref]