Re:Re:Re: [PATCH v2] arch: powerpc: platforms: 85xx: Add missing of_node_put in sgy_cts1000.c

[Liang He]

 2022-06-17 12:29:02，"Michael Ellerman" <mpe@xxxxxxxxxxxxxx> 写道：
>"Liang He" <windhl@xxxxxxx> writes:
>> At 2022-06-17 07:37:06, "Michael Ellerman" <mpe@xxxxxxxxxxxxxx> wrote:
>>>Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> writes:
>>>> Le 16/06/2022 à 17:19, 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 each fail path or when it
>>>>> is not used anymore.
>>>>> 
>>>>> Signed-off-by: Liang He <windhl@xxxxxxx>
>>>>> ---
>>>>>   changelog:
>>>>> 
>>>>>   v2: use goto-label patch style advised by Christophe.
>>>>>   v1: add of_node_put() before each exit.
>>>>> 
>>>>>   arch/powerpc/platforms/85xx/sgy_cts1000.c | 27 +++++++++++++++--------
>>>>>   1 file changed, 18 insertions(+), 9 deletions(-)
>>>>> 
>>>>> diff --git a/arch/powerpc/platforms/85xx/sgy_cts1000.c b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>>>>> index 98ae64075193..e280f963d88c 100644
>>>>> --- a/arch/powerpc/platforms/85xx/sgy_cts1000.c
>>>>> +++ b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>>>>> @@ -73,6 +73,7 @@ static int gpio_halt_probe(struct platform_device *pdev)
>>>...
>>>>> @@ -122,8 +127,12 @@ 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;
>>>>>   
>>>>> -	return 0;
>>>>> +err_put:
>>>>> +	of_node_put(halt_node);
>>>>> +	halt_node = NULL;
>>>>
>>>> Hi,
>>>> so now we set 'halt_node' to NULL even in the normal case.
>>>> This is really spurious.
>>>>
>>>> Look at gpio_halt_cb(), but I think that this is just wrong and badly 
>>>> breaks this driver.
>>>
>>>I agree, thanks for reviewing.
>>>
>>>I think the cleanest solution is to use a local variable for the node in
>>>the body of gpio_halt_probe(), and only assign to halt_node once all the
>>>checks have passed.
>>>
>>>So something like:
>>>
>>>        struct device_node *child_node;
>>>
>>>	child_node = of_find_matching_node(node, child_match);
>>>        ...
>>>
>>>	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);
>>>
>>>out_put:
>>>        of_node_put(child_node);
>>>        
>>>	return ret;
>>>}
>>>
>>>
>>>cheers
>>
>> Hi, Michael and Christophe,
>>
>> I am writing the new patch based on Michael's advice. However, I wonder if there is
>> any place to call of_node_put(halt_node)?  As I do not exactly know if gpio_halt_remove()
>> or anyother place can correctly release this global reference？
>> If not, it is correct that I add a of_node_put(halt_node) in gpio_halt_remove(), right?
>
>Yes I think so, just before it's set to NULL, eg:
>
>diff --git a/arch/powerpc/platforms/85xx/sgy_cts1000.c b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>index 98ae64075193..7beb3cd420ba 100644
>--- a/arch/powerpc/platforms/85xx/sgy_cts1000.c
>+++ b/arch/powerpc/platforms/85xx/sgy_cts1000.c
>@@ -139,6 +139,7 @@ static int gpio_halt_remove(struct platform_device *pdev)
> 
> 		gpio_free(gpio);
> 
>+		of_node_put(halt_node);
> 		halt_node = NULL;
> 	}
> 
>
>cheers



Ok, I will make the new patch soon.