[PATCH v2] pmdomain: mtk-pm-domains: improve spinlock recursion fix in probe with correcting reference count

[PATCH v2] pmdomain: mtk-pm-domains: improve spinlock recursion fix in probe with correcting reference count

[Macpaul Lin]

Remove scpsys_get_legacy_regmap(), replacing its usage with
of_find_node_with_property().  Explicitly call of_node_get(np) before each
of_find_node_with_property() to maintain correct node reference counting.

The of_find_node_with_property() function "consumes" its input by calling
of_node_put() internally, whether or not it finds a match.
Currently, dev->of_node (np) is passed multiple times in sequence without
incrementing its reference count, causing it to be decremented multiple times
and risking early memory release.

Adding of_node_get(np) before each call balances the reference count,
preventing premature node release.

Fixes: c1bac49fe91f ("pmdomains: mtk-pm-domains: Fix spinlock recursion in probe")
Cc: Stable@vger.kernel.org
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Tested-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
---
 drivers/pmdomain/mediatek/mtk-pm-domains.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

Changes for v2:
 - Rewording commit message.
 - Add Fixes: and Tested-by: tag, thanks.

diff --git a/drivers/pmdomain/mediatek/mtk-pm-domains.c b/drivers/pmdomain/mediatek/mtk-pm-domains.c
index 80561d27f2b2..f64f24d520dd 100644
--- a/drivers/pmdomain/mediatek/mtk-pm-domains.c
+++ b/drivers/pmdomain/mediatek/mtk-pm-domains.c
@@ -984,18 +984,6 @@ static void scpsys_domain_cleanup(struct scpsys *scpsys)
 	}
 }
 
-static struct device_node *scpsys_get_legacy_regmap(struct device_node *np, const char *pn)
-{
-	struct device_node *local_node;
-
-	for_each_child_of_node(np, local_node) {
-		if (of_property_present(local_node, pn))
-			return local_node;
-	}
-
-	return NULL;
-}
-
 static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *scpsys)
 {
 	const u8 bp_blocks[3] = {
@@ -1017,7 +1005,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
 	 * this makes it then possible to allocate the array of bus_prot
 	 * regmaps and convert all to the new style handling.
 	 */
-	node = scpsys_get_legacy_regmap(np, "mediatek,infracfg");
+	of_node_get(np);
+	node = of_find_node_with_property(np, "mediatek,infracfg");
 	if (node) {
 		regmap[0] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg");
 		of_node_put(node);
@@ -1030,7 +1019,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
 		regmap[0] = NULL;
 	}
 
-	node = scpsys_get_legacy_regmap(np, "mediatek,smi");
+	of_node_get(np);
+	node = of_find_node_with_property(np, "mediatek,smi");
 	if (node) {
 		smi_np = of_parse_phandle(node, "mediatek,smi", 0);
 		of_node_put(node);
@@ -1048,7 +1038,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
 		regmap[1] = NULL;
 	}
 
-	node = scpsys_get_legacy_regmap(np, "mediatek,infracfg-nao");
+	of_node_get(np);
+	node = of_find_node_with_property(np, "mediatek,infracfg-nao");
 	if (node) {
 		regmap[2] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg-nao");
 		num_regmaps++;
-- 
2.45.2

Re: [PATCH v2] pmdomain: mtk-pm-domains: improve spinlock recursion fix in probe with correcting reference count

[Ulf Hansson]

On Fri, 28 Nov 2025 at 05:17, Macpaul Lin <macpaul.lin@mediatek.com> wrote:
>
> Remove scpsys_get_legacy_regmap(), replacing its usage with
> of_find_node_with_property().  Explicitly call of_node_get(np) before each
> of_find_node_with_property() to maintain correct node reference counting.
>
> The of_find_node_with_property() function "consumes" its input by calling
> of_node_put() internally, whether or not it finds a match.
> Currently, dev->of_node (np) is passed multiple times in sequence without
> incrementing its reference count, causing it to be decremented multiple times
> and risking early memory release.
>
> Adding of_node_get(np) before each call balances the reference count,
> preventing premature node release.
>
> Fixes: c1bac49fe91f ("pmdomains: mtk-pm-domains: Fix spinlock recursion in probe")
> Cc: Stable@vger.kernel.org
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> Tested-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>

Applied for fixes, thanks!

Kind regards
Uffe



> ---
>  drivers/pmdomain/mediatek/mtk-pm-domains.c | 21 ++++++---------------
>  1 file changed, 6 insertions(+), 15 deletions(-)
>
> Changes for v2:
>  - Rewording commit message.
>  - Add Fixes: and Tested-by: tag, thanks.
>
> diff --git a/drivers/pmdomain/mediatek/mtk-pm-domains.c b/drivers/pmdomain/mediatek/mtk-pm-domains.c
> index 80561d27f2b2..f64f24d520dd 100644
> --- a/drivers/pmdomain/mediatek/mtk-pm-domains.c
> +++ b/drivers/pmdomain/mediatek/mtk-pm-domains.c
> @@ -984,18 +984,6 @@ static void scpsys_domain_cleanup(struct scpsys *scpsys)
>         }
>  }
>
> -static struct device_node *scpsys_get_legacy_regmap(struct device_node *np, const char *pn)
> -{
> -       struct device_node *local_node;
> -
> -       for_each_child_of_node(np, local_node) {
> -               if (of_property_present(local_node, pn))
> -                       return local_node;
> -       }
> -
> -       return NULL;
> -}
> -
>  static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *scpsys)
>  {
>         const u8 bp_blocks[3] = {
> @@ -1017,7 +1005,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
>          * this makes it then possible to allocate the array of bus_prot
>          * regmaps and convert all to the new style handling.
>          */
> -       node = scpsys_get_legacy_regmap(np, "mediatek,infracfg");
> +       of_node_get(np);
> +       node = of_find_node_with_property(np, "mediatek,infracfg");
>         if (node) {
>                 regmap[0] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg");
>                 of_node_put(node);
> @@ -1030,7 +1019,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
>                 regmap[0] = NULL;
>         }
>
> -       node = scpsys_get_legacy_regmap(np, "mediatek,smi");
> +       of_node_get(np);
> +       node = of_find_node_with_property(np, "mediatek,smi");
>         if (node) {
>                 smi_np = of_parse_phandle(node, "mediatek,smi", 0);
>                 of_node_put(node);
> @@ -1048,7 +1038,8 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
>                 regmap[1] = NULL;
>         }
>
> -       node = scpsys_get_legacy_regmap(np, "mediatek,infracfg-nao");
> +       of_node_get(np);
> +       node = of_find_node_with_property(np, "mediatek,infracfg-nao");
>         if (node) {
>                 regmap[2] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg-nao");
>                 num_regmaps++;
> --
> 2.45.2
>