linux-kernel - Re: [PATCH 2/2 v3] drivers: use __free attribute instead of of_node

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Date: Wed, 1 May 2024 12:08:45 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Vincenzo Mezzela <vincenzo.mezzela@...il.com>
Cc: gregkh@...uxfoundation.org, javier.carrasco.cruz@...il.com,
	julia.lawall@...ia.fr, linux-kernel@...r.kernel.org,
	rafael@...nel.org, skhan@...uxfoundation.org
Subject: Re: [PATCH 2/2 v3] drivers: use __free attribute instead of
 of_node_put()

As mentioned in 1/2, please fix the subject to be more precise.

On Wed, May 01, 2024 at 11:43:13AM +0200, Vincenzo Mezzela wrote:
> Introduce the __free attribute for scope-based resource management.
> Resources allocated with __free are automatically released at the end of
> the scope. This enhancement aims to mitigate memory management issues
> associated with forgetting to release resources by utilizing __free
> instead of of_node_put().
>
> The declaration of the device_node used within the do-while loops is
> moved directly within the loop so that the resource is automatically
> freed at the end of each iteration.
>
> Suggested-by: Julia Lawall <julia.lawall@...ia.fr>
> Signed-off-by: Vincenzo Mezzela <vincenzo.mezzela@...il.com>
> ---
>  drivers/base/arch_topology.c | 51 +++++++++++++++---------------------
>  1 file changed, 21 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index ea8836f0bb4b..eef26e304018 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -8,6 +8,7 @@
>
>  #include <linux/acpi.h>
>  #include <linux/cacheinfo.h>
> +#include <linux/cleanup.h>
>  #include <linux/cpu.h>
>  #include <linux/cpufreq.h>
>  #include <linux/device.h>
> @@ -513,10 +514,10 @@ core_initcall(free_raw_capacity);
>   */
>  static int __init get_cpu_for_node(struct device_node *node)
>  {
> -	struct device_node *cpu_node;
>  	int cpu;
>
> -	cpu_node = of_parse_phandle(node, "cpu", 0);
> +	struct device_node *cpu_node __free(device_node) =
> +		of_parse_phandle(node, "cpu", 0);

Prefer a blank line after this, applies to all the place where you are
introducing this style.

--
Regards,
Sudeep