linux-kernel - [PATCH v3] clocksource/drivers/timer-ti-dm: fix child node refcount handling

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Message-Id: <20241031-timer-ti-dm-systimer-of_node_put-v3-1-063ee822b73a@gmail.com>
Date: Thu, 31 Oct 2024 13:54:23 +0100
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>, 
 Thomas Gleixner <tglx@...utronix.de>, Tony Lindgren <tony@...mide.com>
Cc: linux-kernel@...r.kernel.org, 
 Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: [PATCH v3] clocksource/drivers/timer-ti-dm: fix child node
 refcount handling

of_find_compatible_node() increments the node's refcount, and it must be
decremented again with a call to of_node_put() when the pointer is no
longer required to avoid leaking the resource.

Instead of adding the missing calls to of_node_put() in all execution
paths, use the cleanup attribute for 'arm_timer' by means of the
__free() macro, which automatically calls of_node_put() when the
variable goes out of scope.

Fixes: 25de4ce5ed02 ("clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
This series adds the missing calls to of_node_put(arm_timer) to release
the resource, and then switches to the more robust approach that makes
use of the automatic cleanup facility (not available for all stable
kernels).
---
Changes in v3:
- Squash patches for mainline solution without intermediate steps.
- Link to v2: https://lore.kernel.org/r/20241028-timer-ti-dm-systimer-of_node_put-v2-0-e6b9a1b3fe67@gmail.com

Changes in v2:
- Add second patch for automatic cleanup.
- Link to v1: https://lore.kernel.org/r/20241013-timer-ti-dm-systimer-of_node_put-v1-1-0cf0c9a37684@gmail.com
---
 drivers/clocksource/timer-ti-dm-systimer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/timer-ti-dm-systimer.c b/drivers/clocksource/timer-ti-dm-systimer.c
index c2dcd8d68e45..d1c144d6f328 100644
--- a/drivers/clocksource/timer-ti-dm-systimer.c
+++ b/drivers/clocksource/timer-ti-dm-systimer.c
@@ -686,9 +686,9 @@ subsys_initcall(dmtimer_percpu_timer_startup);
 
 static int __init dmtimer_percpu_quirk_init(struct device_node *np, u32 pa)
 {
-	struct device_node *arm_timer;
+	struct device_node *arm_timer __free(device_node) =
+		of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
 
-	arm_timer = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
 	if (of_device_is_available(arm_timer)) {
 		pr_warn_once("ARM architected timer wrap issue i940 detected\n");
 		return 0;

---
base-commit: d61a00525464bfc5fe92c6ad713350988e492b88
change-id: 20241013-timer-ti-dm-systimer-of_node_put-d42735687698

Best regards,
-- 
Javier Carrasco <javier.carrasco.cruz@...il.com>