[v2] cpuidle: riscv-sbi: fix device node release in early exit of for_each_possible_cpu

[PATCH v2] cpuidle: riscv-sbi: fix device node release in early exit of for_each_possible_cpu

Posted by Javier Carrasco 3 weeks, 3 days ago

The 'np' device_node is initialized via of_cpu_device_node_get(), which
requires explicit calls to of_node_put() when it 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 'np' by means of the __free()
macro, which automatically calls of_node_put() when the variable goes
out of scope. Given that 'np' is only used within the
for_each_possible_cpu(), reduce its scope to release the nood after
every iteration of the loop.

Fixes: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
Changes in v2:
- Squash patches for mainline solution without intermediate steps.
- Link to v1: https://lore.kernel.org/r/20241030-cpuidle-riscv-sbi-cleanup-v1-0-5e08a22c9409@gmail.com
---
 drivers/cpuidle/cpuidle-riscv-sbi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
index 14462c092039..3a78d6b7598b 100644
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -504,12 +504,13 @@ static int sbi_cpuidle_probe(struct platform_device *pdev)
 	int cpu, ret;
 	struct cpuidle_driver *drv;
 	struct cpuidle_device *dev;
-	struct device_node *np, *pds_node;
+	struct device_node *pds_node;
 
 	/* Detect OSI support based on CPU DT nodes */
 	sbi_cpuidle_use_osi = true;
 	for_each_possible_cpu(cpu) {
-		np = of_cpu_device_node_get(cpu);
+		struct device_node *np __free(device_node) =
+			of_cpu_device_node_get(cpu);
 		if (np &&
 		    of_property_present(np, "power-domains") &&
 		    of_property_present(np, "power-domain-names")) {

---
base-commit: 6fb2fa9805c501d9ade047fc511961f3273cdcb5
change-id: 20241029-cpuidle-riscv-sbi-cleanup-e9b3cb96e16d

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

Re: [PATCH v2] cpuidle: riscv-sbi: fix device node release in early exit of for_each_possible_cpu

Posted by Andrew Jones 1 week, 2 days ago

On Thu, Oct 31, 2024 at 01:21:17PM +0100, Javier Carrasco wrote:
> The 'np' device_node is initialized via of_cpu_device_node_get(), which
> requires explicit calls to of_node_put() when it 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 'np' by means of the __free()
> macro, which automatically calls of_node_put() when the variable goes
> out of scope. Given that 'np' is only used within the
> for_each_possible_cpu(), reduce its scope to release the nood after
> every iteration of the loop.
> 
> Fixes: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver")
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
> Changes in v2:
> - Squash patches for mainline solution without intermediate steps.
> - Link to v1: https://lore.kernel.org/r/20241030-cpuidle-riscv-sbi-cleanup-v1-0-5e08a22c9409@gmail.com
> ---
>  drivers/cpuidle/cpuidle-riscv-sbi.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
> index 14462c092039..3a78d6b7598b 100644
> --- a/drivers/cpuidle/cpuidle-riscv-sbi.c
> +++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
> @@ -504,12 +504,13 @@ static int sbi_cpuidle_probe(struct platform_device *pdev)
>  	int cpu, ret;
>  	struct cpuidle_driver *drv;
>  	struct cpuidle_device *dev;
> -	struct device_node *np, *pds_node;
> +	struct device_node *pds_node;
>  
>  	/* Detect OSI support based on CPU DT nodes */
>  	sbi_cpuidle_use_osi = true;
>  	for_each_possible_cpu(cpu) {
> -		np = of_cpu_device_node_get(cpu);
> +		struct device_node *np __free(device_node) =
> +			of_cpu_device_node_get(cpu);

nit: wrapping the line is unnecessary, we have 100 char width.

>  		if (np &&
>  		    of_property_present(np, "power-domains") &&
>  		    of_property_present(np, "power-domain-names")) {
> 
> ---
> base-commit: 6fb2fa9805c501d9ade047fc511961f3273cdcb5
> change-id: 20241029-cpuidle-riscv-sbi-cleanup-e9b3cb96e16d
> 
> Best regards,
> -- 
> Javier Carrasco <javier.carrasco.cruz@gmail.com>
>

Otherwise,

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>