[PATCH RFC 4/4] of: unittest: cover /aliases updates from overlay apply/revert
From: Abdurrahman Hussain
Date: Mon Jul 20 2026 - 22:54:19 EST
Add overlay_alias.dtso plus of_unittest_overlay_alias() to cover the
"aliases inside an overlay" flow end-to-end.
The overlay has two fragments:
fragment@0: target-path="" grafts a labeled node under target_base.
fragment@1: target-path="/aliases" adds `testcase-alias99 =
&<label>` at DT-root /aliases.
The runner applies the overlay with a non-NULL target_base via
of_overlay_fdt_apply() directly (rather than the overlay_data_apply()
wrapper, which always passes NULL), then asserts of_alias_get_id() on
the grafted node returns 99 across apply and -ENODEV across revert.
Exercises all three functional patches earlier in this series
together:
* the reconfig notifier is what mutates aliases_lookup on
apply/revert;
* find_target()'s absolute-target-path handling is what lets
fragment@1's target-path="/aliases" reach the DT root when
target_base is non-NULL;
* dup_and_fixup_symbol_prop()'s /aliases branch is what rewrites
the fragment-internal alias value ("&<label>" -> fragment path)
into the live-tree path that of_find_node_by_path() can resolve.
Any one of the three missing turns the middle assertion (get_id -> 99)
into -ENODEV.
Signed-off-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
---
drivers/of/unittest-data/Makefile | 2 +
drivers/of/unittest-data/overlay_alias.dtso | 36 ++++++++++++++
drivers/of/unittest.c | 74 +++++++++++++++++++++++++++++
3 files changed, 112 insertions(+)
diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 01a966e39f23..0a8bd9a74283 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtbo.o \
overlay_18.dtbo.o \
overlay_19.dtbo.o \
overlay_20.dtbo.o \
+ overlay_alias.dtbo.o \
overlay_bad_add_dup_node.dtbo.o \
overlay_bad_add_dup_prop.dtbo.o \
overlay_bad_phandle.dtbo.o \
@@ -87,6 +88,7 @@ apply_static_overlay_1 := overlay_0.dtbo \
overlay_18.dtbo \
overlay_19.dtbo \
overlay_20.dtbo \
+ overlay_alias.dtbo \
overlay_gpio_01.dtbo \
overlay_gpio_02a.dtbo \
overlay_gpio_02b.dtbo \
diff --git a/drivers/of/unittest-data/overlay_alias.dtso b/drivers/of/unittest-data/overlay_alias.dtso
new file mode 100644
index 000000000000..7763fffa8699
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_alias.dtso
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/*
+ * overlay_alias - exercise the full "aliases inside an overlay" path.
+ *
+ * fragment@0 grafts a labeled node under target_base (empty target-path
+ * means "the target base itself"). fragment@1 adds a numbered alias at
+ * the DT-root /aliases and points it at that label. target-path="/aliases"
+ * is an absolute path — reaching it while target_base is non-NULL
+ * exercises the absolute-target-paths handling in find_target(). The
+ * alias value is emitted by dtc as the fragment-internal path
+ * "/fragment@0/__overlay__/alias-target"; the overlay code's
+ * /aliases path rewrite is what makes it resolve in the live tree.
+ * The reconfig notifier is what mirrors the change into aliases_lookup.
+ */
+
+/ {
+ fragment@0 {
+ target-path = "";
+ __overlay__ {
+ testcase-target: alias-target {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+ };
+ };
+
+ fragment@1 {
+ target-path = "/aliases";
+ __overlay__ {
+ testcase-alias99 = &testcase-target;
+ };
+ };
+};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index e255f54f4d76..35d75f2b3ef2 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -3475,6 +3475,76 @@ static struct notifier_block of_nb = {
.notifier_call = of_notify,
};
+static void __init of_unittest_overlay_alias(void)
+{
+ const char *base_path =
+ "/testcase-data/overlay-node/test-bus/test-unittest100";
+ const char *target_path =
+ "/testcase-data/overlay-node/test-bus/test-unittest100/alias-target";
+ struct device_node *base, *target;
+ struct overlay_info *info;
+ int ovcs_id = 0;
+ int id, ret;
+ u32 size;
+
+ /*
+ * Apply the overlay with a non-NULL target_base so that
+ * fragment@1's target-path="/aliases" is looked up absolutely
+ * (exercising find_target()'s absolute-path handling) rather
+ * than under the base. The alias value inside the overlay is a
+ * fragment-internal path that only resolves after the overlay
+ * code rewrites /aliases values, so this run covers the whole
+ * chain end-to-end.
+ */
+ base = of_find_node_by_path(base_path);
+ if (!base) {
+ unittest(0, "could not find alias target base %s\n", base_path);
+ return;
+ }
+
+ for (info = overlays; info && info->name; info++)
+ if (!strcmp("overlay_alias", info->name))
+ break;
+ if (!info || !info->name) {
+ unittest(0, "no overlay data for overlay_alias\n");
+ goto out_put_base;
+ }
+
+ size = info->dtbo_end - info->dtbo_begin;
+ ret = of_overlay_fdt_apply(info->dtbo_begin, size, &ovcs_id, base);
+ if (ret < 0) {
+ unittest(0, "overlay_alias apply failed, ret = %d\n", ret);
+ goto out_put_base;
+ }
+
+ target = of_find_node_by_path(target_path);
+ if (!target) {
+ unittest(0, "could not find grafted target %s\n", target_path);
+ goto out_remove;
+ }
+
+ id = of_alias_get_id(target, "testcase-alias");
+ unittest(id == 99,
+ "of_alias_get_id() = %d after overlay apply, expected 99\n",
+ id);
+ of_node_put(target);
+
+out_remove:
+ ret = of_overlay_remove(&ovcs_id);
+ if (ret) {
+ unittest(0, "overlay_alias remove failed, ret = %d\n", ret);
+ goto out_put_base;
+ }
+
+ id = of_alias_get_id(base, "testcase-alias");
+ unittest(id == -ENODEV,
+ "of_alias_get_id() = %d after overlay remove, expected -ENODEV\n",
+ id);
+
+out_put_base:
+ of_node_put(base);
+}
+
static void __init of_unittest_overlay_notify(void)
{
int ovcs_id;
@@ -3649,6 +3719,8 @@ static void __init of_unittest_overlay(void)
of_unittest_overlay_gpio();
+ of_unittest_overlay_alias();
+
of_unittest_remove_tracked_overlays();
of_unittest_overlay_notify();
@@ -3848,6 +3920,7 @@ OVERLAY_INFO_EXTERN(overlay_17);
OVERLAY_INFO_EXTERN(overlay_18);
OVERLAY_INFO_EXTERN(overlay_19);
OVERLAY_INFO_EXTERN(overlay_20);
+OVERLAY_INFO_EXTERN(overlay_alias);
OVERLAY_INFO_EXTERN(overlay_gpio_01);
OVERLAY_INFO_EXTERN(overlay_gpio_02a);
OVERLAY_INFO_EXTERN(overlay_gpio_02b);
@@ -3885,6 +3958,7 @@ static struct overlay_info overlays[] = {
OVERLAY_INFO(overlay_18, 0, 0),
OVERLAY_INFO(overlay_19, 0, 0),
OVERLAY_INFO(overlay_20, 0, 0),
+ OVERLAY_INFO(overlay_alias, 0, 0),
OVERLAY_INFO(overlay_gpio_01, 0, 0),
OVERLAY_INFO(overlay_gpio_02a, 0, 0),
OVERLAY_INFO(overlay_gpio_02b, 0, 0),
--
2.54.0