linux-kernel - Re: [PATCH v4] irqchip/renesas-rzg2l: Fix missing put

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Message-ID: <CA+V-a8tfBftutbXCuAjTXJ3H65enOENtSdTWXATfa1VZN+LTfA@mail.gmail.com>
Date: Thu, 17 Oct 2024 13:21:46 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Markus Elfring <elfring@...rs.sourceforge.net>, 
	Markus Elfring <Markus.Elfring@....de>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Marc Zyngier <maz@...nel.org>, Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, 
	linux-kernel@...r.kernel.org, Chris Paterson <Chris.Paterson2@...esas.com>, 
	Biju Das <biju.das.jz@...renesas.com>, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v4] irqchip/renesas-rzg2l: Fix missing put_device

On Fri, Oct 11, 2024 at 6:20 PM Fabrizio Castro
<fabrizio.castro.jz@...esas.com> wrote:
>
> rzg2l_irqc_common_init calls of_find_device_by_node, but the
> corresponding put_device call is missing.
> This also gets reported by make coccicheck.
>
> Make use of the cleanup interfaces from cleanup.h to call into
> __free_put_device (which in turn calls into put_device) when
> leaving function rzg2l_irqc_common_init and variable "dev" goes
> out of scope.
>
> Mind that we don't want to "put" "dev" when rzg2l_irqc_common_init
> completes successfully, therefore assign NULL to "dev" to prevent
> __free_put_device from calling into put_device within the successful
> path.
>
> "make coccicheck" will still complain about missing put_device calls,
> but those are false positives now.
>
> Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> ---
>
> v3->v4:
>  * switched to using the cleanup interfaces as an alternative to using
>    goto chains
>
>  drivers/irqchip/irq-renesas-rzg2l.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Cheers,
Prabhakar

> diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
> index 693ff285ca2c..99e27e01b0b1 100644
> --- a/drivers/irqchip/irq-renesas-rzg2l.c
> +++ b/drivers/irqchip/irq-renesas-rzg2l.c
> @@ -8,6 +8,7 @@
>   */
>
>  #include <linux/bitfield.h>
> +#include <linux/cleanup.h>
>  #include <linux/clk.h>
>  #include <linux/err.h>
>  #include <linux/io.h>
> @@ -530,12 +531,12 @@ static int rzg2l_irqc_parse_interrupts(struct rzg2l_irqc_priv *priv,
>  static int rzg2l_irqc_common_init(struct device_node *node, struct device_node *parent,
>                                   const struct irq_chip *irq_chip)
>  {
> +       struct platform_device *pdev = of_find_device_by_node(node);
> +       struct device *dev __free(put_device) = pdev ? &pdev->dev : NULL;
>         struct irq_domain *irq_domain, *parent_domain;
> -       struct platform_device *pdev;
>         struct reset_control *resetn;
>         int ret;
>
> -       pdev = of_find_device_by_node(node);
>         if (!pdev)
>                 return -ENODEV;
>
> @@ -591,6 +592,17 @@ static int rzg2l_irqc_common_init(struct device_node *node, struct device_node *
>
>         register_syscore_ops(&rzg2l_irqc_syscore_ops);
>
> +       /*
> +        * Prevent the cleanup function from invoking put_device by assigning
> +        * NULL to dev.
> +        *
> +        * make coccicheck will complain about missing put_device calls, but
> +        * those are false positives, as dev will be automatically "put" via
> +        * __free_put_device on the failing path.
> +        * On the successful path we don't actually want to "put" dev.
> +        */
> +       dev = NULL;
> +
>         return 0;
>
>  pm_put:
> --
> 2.34.1
>
>