Re: [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API

[Tyrel Datwyler <tyreld@linux.ibm.com>]

On 7/1/22 12:47, Tyrel Datwyler wrote:
> On 7/1/22 06:17, Liang He wrote:
>> In pci_add_device_node_info(), we should use of_node_put() for the
>> reference 'parent' returned by of_get_parent() to keep refcount
>> balance.
>>
>> Fixes: cca87d303c85 ("powerpc/pci: Refactor pci_dn")
>> Co-authored-by: Miaoqian Lin <linmq006@gmail.com>
>> Signed-off-by: Liang He <windhl@126.com>
>> ---
>>  arch/powerpc/kernel/pci_dn.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/powerpc/kernel/pci_dn.c b/arch/powerpc/kernel/pci_dn.c
>> index 938ab8838ab5..aa221958007e 100644
>> --- a/arch/powerpc/kernel/pci_dn.c
>> +++ b/arch/powerpc/kernel/pci_dn.c
>> @@ -330,6 +330,7 @@ struct pci_dn *pci_add_device_node_info(struct pci_controller *hose,
>>  	INIT_LIST_HEAD(&pdn->list);
>>  	parent = of_get_parent(dn);
>>  	pdn->parent = parent ? PCI_DN(parent) : NULL;
> NACK
> 
> pdn->parent is now a long term reference so we should not do a put on parent
> until we pdn->parent is no longer valid.

I withdraw my NACK. On closer inspection pdn->parent is a reference to the
parent struct pci_dn and not a reference to a parent struct device_node.

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

> 
> -Tyrel
> 
>> +	of_node_put(parent);
>>  	if (pdn->parent)
>>  		list_add_tail(&pdn->list, &pdn->parent->child_list);
>>
>