linux-kernel - Re:Re: [PATCH v3] powerpc:85xx: Add missing of_node_put() in sgy

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Message-ID: <7d68d310.3bb6.1817036a352.Coremail.windhl@126.com>
Date:   Fri, 17 Jun 2022 13:50:37 +0800 (CST)
From:   "Liang He" <windhl@....com>
To:     "Christophe JAILLET" <christophe.jaillet@...adoo.fr>
Cc:     oss@...error.net, mpe@...erman.id.au, benh@...nel.crashing.org,
        paulus@...ba.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re:Re: [PATCH v3] powerpc:85xx: Add missing of_node_put() in
 sgy_cst1000



At 2022-06-17 13:37:12, "Christophe JAILLET" <christophe.jaillet@...adoo.fr> wrote:
>Le 17/06/2022 à 07:22, 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>
>> ---
>>   arch/powerpc/platforms/85xx/sgy_cts1000.c | 39 +++++++++++++++--------
>>   1 file changed, 25 insertions(+), 14 deletions(-)
>> 
>> diff --git a/arch/powerpc/platforms/85xx/sgy_cts1000.c b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>> index 98ae64075193..a8690fc552cf 100644
>> --- a/arch/powerpc/platforms/85xx/sgy_cts1000.c
>> +++ b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>> @@ -71,33 +71,39 @@ 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;
>> +	int ret;
>>   
>>   	if (!node)
>>   		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) {
>> +		ret = -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)) {
>> +		ret = -EINVAL;
>> +		gotot err_put;
>> +	}
>>   
>>   	err = gpio_request(gpio, "gpio-halt");
>>   	if (err) {
>>   		printk(KERN_ERR "gpio-halt: error requesting GPIO %d.\n",
>>   		       gpio);
>> -		halt_node = NULL;
>> -		return err;
>> +		ret = err;
>
>Sorry for not seeing and asking before, but why do you need 'ret'?
>Can't you use the existing 'err' in place in this whole patch?
>

Thanks, CJ.

Your advice is good and I have not noticed the 'err'.

>> +		goto err_put;
>>   	}
>>   
>>   	trigger = (flags == OF_GPIO_ACTIVE_LOW);
>> @@ -105,15 +111,15 @@ 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;
>> +		ret = err;
>> +		goto err_put;
>>   	}
>>   
>>   	/* Register our halt function */
>> @@ -122,8 +128,12 @@ 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);
>> +	ret = 0;
>> +	halt_node = of_node_get(child_node);
>
>LGTM, but my preferred style would be:
>	halt_node = child_node;
>	return 0;
>I'm not a maintainer, so this is just my opinion and it is mostly a 
>mater of taste.
>
>CJ

Thanks, CJ.

Now, I also prefer this style and I will use it.

>
>>   
>> -	return 0;
>> +err_put:
>> +	of_node_put(child_node);
>> +	return ret;
>>   }
>>   
>>   static int gpio_halt_remove(struct platform_device *pdev)
>> @@ -139,6 +149,7 @@ static int gpio_halt_remove(struct platform_device *pdev)
>>   
>>   		gpio_free(gpio);
>>   
>> +		of_node_put(halt_node);
>>   		halt_node = NULL;
>>   	}
>>