"Liang He" <win...@126.com> writes:
> At 2022-06-17 07:37:06, "Michael Ellerman" <m...@ellerman.id.au> wrote:
>>Christophe JAILLET <christophe.jail...@wanadoo.fr> 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 <win...@126.com>
>>>> ---
>>>> 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
