linux-kernel - Re: [PATCH v4] powerpc:85xx: Add missing of_node_put() in sgy

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Message-ID: <eb72976a-9ca3-b894-b2d5-8283a4cf486d@csgroup.eu>
Date:   Fri, 17 Jun 2022 06:28:56 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Liang He <windhl@....com>, "oss@...error.net" <oss@...error.net>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "paulus@...ba.org" <paulus@...ba.org>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] powerpc:85xx: Add missing of_node_put() in sgy_cst1000



Le 17/06/2022 à 08:08, Liang He a écrit :
> In gpio_halt_probe(), of_find_matching_node() will return a node
> pointer with refcount incremented. We should use of_node_put() in
> fail path or when it is not used anymore.
> 
> Signed-off-by: Liang He <windhl@....com>
> ---
>   changelog:
>   v4: reuse exist 'err' and use a simple code style, advised by CJ
>   v3: use local 'child_node' advised by Michael.
>   v2: use goto-label patch style advised by Christophe Leroy.
>   v1: add of_node_put() before each exit.
> 
>   arch/powerpc/platforms/85xx/sgy_cts1000.c | 35 ++++++++++++++---------
>   1 file changed, 22 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/85xx/sgy_cts1000.c b/arch/powerpc/platforms/85xx/sgy_cts1000.c
> index 98ae64075193..e4588943fe7e 100644
> --- a/arch/powerpc/platforms/85xx/sgy_cts1000.c
> +++ b/arch/powerpc/platforms/85xx/sgy_cts1000.c
> @@ -71,6 +71,7 @@ static int gpio_halt_probe(struct platform_device *pdev)
>   {
>   	enum of_gpio_flags flags;
>   	struct device_node *node = pdev->dev.of_node;
> +	struct device_node *child_node;
>   	int gpio, err, irq;
>   	int trigger;
>   
> @@ -78,26 +79,29 @@ static int gpio_halt_probe(struct platform_device *pdev)
>   		return -ENODEV;
>   
>   	/* If there's no matching child, this isn't really an error */
> -	halt_node = of_find_matching_node(node, child_match);
> -	if (!halt_node)
> +	child_node = of_find_matching_node(node, child_match);
> +	if (!child_node)
>   		return 0;
>   
>   	/* Technically we could just read the first one, but punish
>   	 * DT writers for invalid form. */
> -	if (of_gpio_count(halt_node) != 1)
> -		return -EINVAL;
> +	if (of_gpio_count(child_node) != 1) {
> +		err = -EINVAL;
> +		goto err_put;
> +	}
>   
>   	/* Get the gpio number relative to the dynamic base. */
> -	gpio = of_get_gpio_flags(halt_node, 0, &flags);
> -	if (!gpio_is_valid(gpio))
> -		return -EINVAL;
> +	gpio = of_get_gpio_flags(child_node, 0, &flags);
> +	if (!gpio_is_valid(gpio)) {
> +		err = -EINVAL;
> +		gotot err_put;

Did you test the build ?

> +	}
>   
>   	err = gpio_request(gpio, "gpio-halt");
>   	if (err) {
>   		printk(KERN_ERR "gpio-halt: error requesting GPIO %d.\n",
>   		       gpio);
> -		halt_node = NULL;
> -		return err;
> +		goto err_put;
>   	}
>   
>   	trigger = (flags == OF_GPIO_ACTIVE_LOW);
> @@ -105,15 +109,14 @@ static int gpio_halt_probe(struct platform_device *pdev)
>   	gpio_direction_output(gpio, !trigger);
>   
>   	/* Now get the IRQ which tells us when the power button is hit */
> -	irq = irq_of_parse_and_map(halt_node, 0);
> +	irq = irq_of_parse_and_map(child_node, 0);
>   	err = request_irq(irq, gpio_halt_irq, IRQF_TRIGGER_RISING |
> -			  IRQF_TRIGGER_FALLING, "gpio-halt", halt_node);
> +			  IRQF_TRIGGER_FALLING, "gpio-halt", child_node);
>   	if (err) {
>   		printk(KERN_ERR "gpio-halt: error requesting IRQ %d for "
>   		       "GPIO %d.\n", irq, gpio);
>   		gpio_free(gpio);
> -		halt_node = NULL;
> -		return err;
> +		goto err_put;
>   	}
>   
>   	/* Register our halt function */
> @@ -123,7 +126,12 @@ static int gpio_halt_probe(struct platform_device *pdev)
>   	printk(KERN_INFO "gpio-halt: registered GPIO %d (%d trigger, %d"
>   	       " irq).\n", gpio, trigger, irq);
>   
> +	halt_node = child_node;
>   	return 0;
> +
> +err_put:
> +	of_node_put(child_node);
> +	return err;
>   }
>   
>   static int gpio_halt_remove(struct platform_device *pdev)
> @@ -139,6 +147,7 @@ static int gpio_halt_remove(struct platform_device *pdev)
>   
>   		gpio_free(gpio);
>   
> +		of_node_put(halt_node);
>   		halt_node = NULL;
>   	}
>