of: overlay: Move devicetree_corrupt() check up

There is no point in doing several preparatory steps in
of_overlay_fdt_apply(), only to see of_overlay_apply() return early
because of a corrupt device tree.

Move the check for a corrupt device tree from of_overlay_apply() to
of_overlay_fdt_apply(), to check for this as early as possible.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Tested-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/c91ce7112eb5167ea46a43d8a980e76b920010ba.1657893306.git.geert+renesas@glider.be

drivers/of/overlay.c

@@ -903,12 +903,6 @@ static int of_overlay_apply(struct overlay_changeset *ovcs)
 {
 	int ret = 0, ret_revert, ret_tmp;
 
-	if (devicetree_corrupt()) {
-		pr_err("devicetree state suspect, refuse to apply overlay\n");
-		ret = -EBUSY;
-		goto out;
-	}
-
 	ret = of_resolve_phandles(ovcs->overlay_root);
 	if (ret)
 		goto out;
@@ -983,6 +977,11 @@ int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
 
 	*ret_ovcs_id = 0;
 
+	if (devicetree_corrupt()) {
+		pr_err("devicetree state suspect, refuse to apply overlay\n");
+		return -EBUSY;
+	}
+
 	if (overlay_fdt_size < sizeof(struct fdt_header) ||
 	    fdt_check_header(overlay_fdt)) {
 		pr_err("Invalid overlay_fdt header\n");