linux-kernel - Re: [PATCH] drivers: hwmon: Add missing of_node

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Date:   Wed, 15 Jun 2022 20:05:58 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     和亮 <windhl@....com>
Cc:     tharvey@...eworks.com, rjones@...eworks.com, jdelvare@...e.com,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: hwmon: Add missing of_node_put() in gsc-hwmon.c

On 6/15/22 19:37, 和亮 wrote:
> 
> 
> 
> At 2022-06-16 01:57:49, "Guenter Roeck" <linux@...ck-us.net> wrote:
>>
>> Please use proper subject lines. Here it should have been
>>
>> hwmon: (gsc-hwmon) Add missing of_node_put()
> 
> 
> 
> Thanks, I will change it in my new patch.
> 
> 
>>>>    drivers/hwmon/gsc-hwmon.c | 6 +++++-
>>>    1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/gsc-hwmon.c b/drivers/hwmon/gsc-hwmon.c
>>> index 1fe37418ff46..34c20d13627a 100644
>>> --- a/drivers/hwmon/gsc-hwmon.c
>>> +++ b/drivers/hwmon/gsc-hwmon.c
>>> @@ -268,10 +268,14 @@ gsc_hwmon_get_devtree_pdata(struct device *dev)
>>>    
>>>    	/* fan controller base address */
>>>    	fan = of_find_compatible_node(dev->parent->of_node, NULL, "gw,gsc-fan");
>>
>> A single of_node_put(fan) here would have been be sufficient.
> 
> 
> 
> I think of_node_put after should come after its usage, right?
> 
> 

Yes, you are correct. Sorry for the noise.

>>>> -	if (fan && of_property_read_u32(fan, "reg", &pdata->fan_base)) {
>>> +	if (fan && of_property_read_u32(fan, "reg", &pdata->fan_base)) {		
>>> +		of_node_put(fan);
>>>    		dev_err(dev, "fan node without base\n");
>>>    		return ERR_PTR(-EINVAL);
>>>    	}
>>> +	
>>> +	/* if fan&&!of_property_read_u32 fail */
>>
> 
>> This comment only adds confusion and does not add any value.
> 
> 
> Sorry, I just want to say, if *fan* is not NULL, but of_property_read_u32() returns 0.
> In that case, we still need a of_node_put() to release fan, right?
> 

Yes, but that is obvious, and the comment is not needed.

Thanks,
Guenter

>>
>> Guenter
>>
>>> +	of_node_put(fan);
>>>    
>>>    	/* allocate structures for channels and count instances of each type */
> 
>>>    	device_for_each_child_node(dev, child) {
> 
> 
> Hi, Guenter, I am preparing my new patch and I want to discuss your suggestions as above.
>