[PATCH 0/2] cpufreq: dt/dt-platdev: eliminate uses of of_node_put()

[PATCH 0/2] cpufreq: dt/dt-platdev: eliminate uses of of_node_put()

[Javier Carrasco]

This series removes uses of of_node_put() in dt and dt-platdev, which
can be replaced with the clenaup handler introduced with
54da6a092431 ("locking: Introduce __cleanup() based infrastructure").

This change provides a scope-based cleanup mechanism to avoid potential
memory leaks that can appear if of_node_put() is not used correctly.

The series is based on linux-next (next-20240422) and has been validated
with a Rockchip RK3568 that makes use of these drivers.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
Javier Carrasco (2):
      cpufreq: dt: eliminate uses of of_node_put()
      cpufreq: dt-platdev: eliminate uses of of_node_put()

 drivers/cpufreq/cpufreq-dt-platdev.c |  7 ++-----
 drivers/cpufreq/cpufreq-dt.c         | 21 ++++++---------------
 2 files changed, 8 insertions(+), 20 deletions(-)
---
base-commit: f529a6d274b3b8c75899e949649d231298f30a32
change-id: 20240422-of_node_put_cpufreq_dt-9c5354d9e9f0

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

[PATCH 1/2] cpufreq: dt: eliminate uses of of_node_put()

[Javier Carrasco]

Make use of the __free() cleanup handler to automatically free nodes
when they get out of scope.

Only find_supply_name() is affected, and the new mechanism removes the
need for a 'goto' and the 'name' local variable.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/cpufreq/cpufreq-dt.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index 2d83bbc65dd0..907e22632fda 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -68,12 +68,9 @@ static int set_target(struct cpufreq_policy *policy, unsigned int index)
  */
 static const char *find_supply_name(struct device *dev)
 {
-	struct device_node *np;
+	struct device_node *np __free(device_node) = of_node_get(dev->of_node);
 	struct property *pp;
 	int cpu = dev->id;
-	const char *name = NULL;
-
-	np = of_node_get(dev->of_node);
 
 	/* This must be valid for sure */
 	if (WARN_ON(!np))
@@ -82,22 +79,16 @@ static const char *find_supply_name(struct device *dev)
 	/* Try "cpu0" for older DTs */
 	if (!cpu) {
 		pp = of_find_property(np, "cpu0-supply", NULL);
-		if (pp) {
-			name = "cpu0";
-			goto node_put;
-		}
+		if (pp)
+			return "cpu0";
 	}
 
 	pp = of_find_property(np, "cpu-supply", NULL);
-	if (pp) {
-		name = "cpu";
-		goto node_put;
-	}
+	if (pp)
+		return "cpu";
 
 	dev_dbg(dev, "no regulator for cpu%d\n", cpu);
-node_put:
-	of_node_put(np);
-	return name;
+	return NULL;
 }
 
 static int cpufreq_init(struct cpufreq_policy *policy)

-- 
2.40.1

[PATCH 2/2] cpufreq: dt-platdev: eliminate uses of of_node_put()

[Javier Carrasco]

Make use of the __free() cleanup handler to automatically free nodes
when they get out of scope.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/cpufreq/cpufreq-dt-platdev.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index 86d8baa81679..c74dd1e01e0d 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -198,19 +198,18 @@ static const struct of_device_id blocklist[] __initconst = {
 
 static bool __init cpu0_node_has_opp_v2_prop(void)
 {
-	struct device_node *np = of_cpu_device_node_get(0);
+	struct device_node *np __free(device_node) = of_cpu_device_node_get(0);
 	bool ret = false;
 
 	if (of_property_present(np, "operating-points-v2"))
 		ret = true;
 
-	of_node_put(np);
 	return ret;
 }
 
 static int __init cpufreq_dt_platdev_init(void)
 {
-	struct device_node *np = of_find_node_by_path("/");
+	struct device_node *np __free(device_node) = of_find_node_by_path("/");
 	const struct of_device_id *match;
 	const void *data = NULL;
 
@@ -226,11 +225,9 @@ static int __init cpufreq_dt_platdev_init(void)
 	if (cpu0_node_has_opp_v2_prop() && !of_match_node(blocklist, np))
 		goto create_pdev;
 
-	of_node_put(np);
 	return -ENODEV;
 
 create_pdev:
-	of_node_put(np);
 	return PTR_ERR_OR_ZERO(platform_device_register_data(NULL, "cpufreq-dt",
 			       -1, data,
 			       sizeof(struct cpufreq_dt_platform_data)));

-- 
2.40.1

Re: [PATCH 0/2] cpufreq: dt/dt-platdev: eliminate uses of of_node_put()

[Viresh Kumar]

On 23-04-24, 10:27, Javier Carrasco wrote:
> This series removes uses of of_node_put() in dt and dt-platdev, which
> can be replaced with the clenaup handler introduced with
> 54da6a092431 ("locking: Introduce __cleanup() based infrastructure").
> 
> This change provides a scope-based cleanup mechanism to avoid potential
> memory leaks that can appear if of_node_put() is not used correctly.
> 
> The series is based on linux-next (next-20240422) and has been validated
> with a Rockchip RK3568 that makes use of these drivers.
> 
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
> Javier Carrasco (2):
>       cpufreq: dt: eliminate uses of of_node_put()
>       cpufreq: dt-platdev: eliminate uses of of_node_put()
> 
>  drivers/cpufreq/cpufreq-dt-platdev.c |  7 ++-----
>  drivers/cpufreq/cpufreq-dt.c         | 21 ++++++---------------
>  2 files changed, 8 insertions(+), 20 deletions(-)

Applied. Thanks.

-- 
viresh