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

From: Liang He
Date: Fri Jun 17 2022 - 01:14:46 EST




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.