[PATCH] of: never fixup internal live tree

Sascha Hauer s.hauer at pengutronix.de
Thu Aug 3 01:51:34 PDT 2023

Calling of_fix_tree() on the internal live tree has undesired side
effects, so refrain from doing so.

One of the side effects is that some parts of barebox store pointers
to properties in the live tree which might become invalid when during
of_fixup these properties are deleted or updated.

The other is that it's unexpected that the live tree is modified
after a dry run boot with the live tree.

This changes of_get_fixed_tree() to always call of_fix_tree() on
a copy of the device tree and not on the device tree itself. To
emphasize this make the device tree argument to of_get_fixed_tree()

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
 common/oftree.c | 19 ++++++++++---------
 include/of.h    |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/common/oftree.c b/common/oftree.c
index 3e85070d11..51eebd36bd 100644
--- a/common/oftree.c
+++ b/common/oftree.c
@@ -416,26 +416,27 @@ void of_fix_tree(struct device_node *node)
  * It increases the size of the tree and applies the registered
  * fixups.
-struct fdt_header *of_get_fixed_tree(struct device_node *node)
+struct fdt_header *of_get_fixed_tree(const struct device_node *node)
 	struct fdt_header *fdt = NULL;
-	struct device_node *freenp = NULL;
+	struct device_node *np;
 	if (!node) {
 		node = of_get_root_node();
 		if (!node)
 			return NULL;
-		freenp = node = of_dup(node);
-		if (!node)
-			return NULL;
-	of_fix_tree(node);
+	np = of_dup(node);
+	if (!np)
+		return NULL;
+	of_fix_tree(np);
-	fdt = of_flatten_dtb(node);
+	fdt = of_flatten_dtb(np);
-	of_delete_node(freenp);
+	of_delete_node(np);
 	return fdt;
diff --git a/include/of.h b/include/of.h
index 92a15f5c4a..0deb327971 100644
--- a/include/of.h
+++ b/include/of.h
@@ -75,7 +75,7 @@ int of_add_initrd(struct device_node *root, resource_size_t start,
 struct fdt_header *fdt_get_tree(void);
-struct fdt_header *of_get_fixed_tree(struct device_node *node);
+struct fdt_header *of_get_fixed_tree(const struct device_node *node);
 /* Helper to read a big number; size is in cells (not bytes) */
 static inline u64 of_read_number(const __be32 *cell, int size)

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