[PATCH master] of: base: handle of_set_root_node(NULL) correctly

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

of_set_root_node(NULL) used to be valid and the if clause at the start
of the function explicitly allowed of it.

This was broken by the unconditional use of of_property_write_bool, so
guard that behind the existence of a root node.

Fixes: b1ced2c3caa9 ("state: suppress state overwrite warning for barebox DT")
Reported-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/of/base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d4fbd2367baf..57b64bc0b96c 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2123,15 +2123,17 @@ int of_set_root_node(struct device_node *node)
 	if (node && root_node)
 		return -EBUSY;
 
 	root_node = node;
 
 	of_chosen = of_find_node_by_path("/chosen");
 	of_property_read_string(root_node, "model", &of_model);
-	of_property_write_bool(root_node, "$barebox,root-node", true);
+
+	if (root_node)
+		of_property_write_bool(root_node, "$barebox,root-node", true);
 
 	if (of_model)
 		barebox_set_model(of_model);
 
 	of_alias_scan();
 
 	return 0;
-- 
2.47.3