[PATCH v3] soc: samsung: exynos-pmu: fix of_node refcount leak in exynos_get_pmu_regmap()

[Weigang He <geoffreyhe2@gmail.com>]

exynos_get_pmu_regmap() obtains a device_node via of_find_matching_node()
and passes it to exynos_get_pmu_regmap_by_phandle(np, NULL). With
propname == NULL the callee uses np directly and does not drop a
reference, so the reference taken by of_find_matching_node() is leaked on
every call -- including on each -EPROBE_DEFER retry of the only in-tree
caller, exynos_retention_init() in the Exynos pinctrl driver.

Annotate np with the __free(device_node) cleanup attribute so the
reference is released when the function returns.

Found by static analysis tool CodeQL.

Fixes: 76640b84bd7a ("soc: samsung: pmu: Provide global function to get PMU regmap")
Signed-off-by: Weigang He <geoffreyhe2@gmail.com>
---
Changes in v3:
 - Only annotate the np declaration with __free(device_node); leave the
   rest of the function body unchanged (Krzysztof Kozlowski).

Changes in v2:
 - Use the __free(device_node) cleanup attribute instead of an explicit
   of_node_put() and the helper refactor (Krzysztof Kozlowski); dropped
   the former patch 2/2.

v2: https://lore.kernel.org/linux-samsung-soc/20260609133320.1748882-1-geoffreyhe2@gmail.com/
v1: https://lore.kernel.org/linux-samsung-soc/20260609095224.1706036-2-geoffreyhe2@gmail.com>/

 drivers/soc/samsung/exynos-pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index d58376c38179b..f5fcdde9750e2 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -167,8 +167,8 @@ static const struct mfd_cell exynos_pmu_devs[] = {
  */
 struct regmap *exynos_get_pmu_regmap(void)
 {
-	struct device_node *np = of_find_matching_node(NULL,
-						      exynos_pmu_of_device_ids);
+	struct device_node *np __free(device_node) =
+		of_find_matching_node(NULL, exynos_pmu_of_device_ids);
 	if (np)
 		return exynos_get_pmu_regmap_by_phandle(np, NULL);
 	return ERR_PTR(-ENODEV);

base-commit: 0f61b1860cc3f52aef9036d7235ed1f017632193
-- 
2.43.0