[PATCH v2] of: unittest: Fix np reference leak in of_unittest_bus_3cell_ranges()

[Wentao Liang <vulab@iscas.ac.cn>]

of_range_parser_init() can fail when the node lacks a ranges property.
That error path returns without dropping the reference taken by
of_find_node_by_path(). Make the reference cleanup-managed so that it is
released on every return path, rather than adding an of_node_put() to
this one path only.

The candidate was found with static analysis tools; DeepSeek and GPT-6.1
Sol were used to audit it and to help prepare this fix.

Fixes: 3d5089c4263d ("of/address: Add support for 3 address cell bus")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
Changes in v2:
- Sorry for the very late reply to your review.
- Use __free(device_node) instead of an extra of_node_put() on the error
  path, as you suggested, so that every return path releases the node.
- Drop Cc: stable@vger.kernel.org.
- The other unittest fixes from that batch need the same rework. I am
  not resending them as a series of individual patches.
- Rebased on current mainline (fa4ad798f6f6). Built with arm64 defconfig
  plus CONFIG_OF_UNITTEST=y and W=1: drivers/of/unittest.o compiles
  without warnings and checkpatch.pl --strict is clean. I could not run
  the unittest at boot, so the error path itself was not exercised.
- Link to v1: https://lore.kernel.org/all/20260917124653.2151894-1-vulab@iscas.ac.cn/

 drivers/of/unittest.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index e255f54f4d76..b6f0ae3e9710 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1366,12 +1366,12 @@ static void __init of_unittest_bus_ranges(void)
 
 static void __init of_unittest_bus_3cell_ranges(void)
 {
-	struct device_node *np;
+	struct device_node *np __free(device_node) =
+		of_find_node_by_path("/testcase-data/address-tests/bus@a0000000");
 	struct of_range range;
 	struct of_range_parser parser;
 	int i = 0;
 
-	np = of_find_node_by_path("/testcase-data/address-tests/bus@a0000000");
 	if (!np) {
 		pr_err("missing testcase data\n");
 		return;
@@ -1415,8 +1415,6 @@ static void __init of_unittest_bus_3cell_ranges(void)
 		}
 		i++;
 	}
-
-	of_node_put(np);
 }
 
 static void __init of_unittest_reg(void)
-- 
2.34.1