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

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Message-ID: <20241115-20b5e02dd05173bfdc3a7d7f@orel>
Date: Fri, 15 Nov 2024 14:24:24 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Javier Carrasco <javier.carrasco.cruz@...il.com>
Cc: Anup Patel <anup@...infault.org>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Atish Patra <atishp@...osinc.com>, 
	Palmer Dabbelt <palmer@...osinc.com>, linux-pm@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] cpuidle: riscv-sbi: fix device node release in early
 exit of for_each_possible_cpu

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@...il.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@...il.com>
>

Otherwise,

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