* [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
@ 2022-07-01 13:17 Liang He
2022-07-01 19:47 ` Tyrel Datwyler
2022-09-09 12:07 ` Michael Ellerman
0 siblings, 2 replies; 5+ messages in thread
From: Liang He @ 2022-07-01 13:17 UTC (permalink / raw)
To: mpe, benh, paulus, windhl, linuxppc-dev, linmq006
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;
+ of_node_put(parent);
if (pdn->parent)
list_add_tail(&pdn->list, &pdn->parent->child_list);
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
2022-07-01 13:17 [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API Liang He
@ 2022-07-01 19:47 ` Tyrel Datwyler
2022-07-01 21:36 ` Liang He
2022-07-01 22:18 ` Tyrel Datwyler
2022-09-09 12:07 ` Michael Ellerman
1 sibling, 2 replies; 5+ messages in thread
From: Tyrel Datwyler @ 2022-07-01 19:47 UTC (permalink / raw)
To: Liang He, mpe, benh, paulus, linuxppc-dev, linmq006
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.
-Tyrel
> + of_node_put(parent);
> if (pdn->parent)
> list_add_tail(&pdn->list, &pdn->parent->child_list);
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re:Re: [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
2022-07-01 19:47 ` Tyrel Datwyler
@ 2022-07-01 21:36 ` Liang He
2022-07-01 22:18 ` Tyrel Datwyler
1 sibling, 0 replies; 5+ messages in thread
From: Liang He @ 2022-07-01 21:36 UTC (permalink / raw)
To: Tyrel Datwyler; +Cc: linmq006, paulus, linuxppc-dev
At 2022-07-02 03:47:22, "Tyrel Datwyler" <tyreld@linux.ibm.com> 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.
>
>-Tyrel
Hi, Tyrel
Thanks for reviewing this code.
But I think there is some confusion about the of_get_parent() and I can confirm
my point when I check the 'pci_remove_device_node_info' function, which may be
a second bug.
In pci_remove_device_node_info(), I notice the comment, 'Drop the parent pci_dn's ref ...'.
However, of_get_parent() will increase the refcount of the parent, and then the
following of_node_put() will decrease the refcount, so, finally, there is no any change.
Back to this case, as the 'pdn->parent' is not the reference of parent device_node, it is
device_node's data, so I think it is better to keep the original meaning of refcounting, i.e,
add a of_node_put() to keep the refcount balance.
If I have some mis-understanding, please correct me.
Thanks,
Liang
>
>> + of_node_put(parent);
>> if (pdn->parent)
>> list_add_tail(&pdn->list, &pdn->parent->child_list);
>>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
2022-07-01 19:47 ` Tyrel Datwyler
2022-07-01 21:36 ` Liang He
@ 2022-07-01 22:18 ` Tyrel Datwyler
1 sibling, 0 replies; 5+ messages in thread
From: Tyrel Datwyler @ 2022-07-01 22:18 UTC (permalink / raw)
To: Liang He, mpe, benh, paulus, linuxppc-dev, linmq006
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);
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
2022-07-01 13:17 [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API Liang He
2022-07-01 19:47 ` Tyrel Datwyler
@ 2022-09-09 12:07 ` Michael Ellerman
1 sibling, 0 replies; 5+ messages in thread
From: Michael Ellerman @ 2022-09-09 12:07 UTC (permalink / raw)
To: linuxppc-dev, paulus, Liang He, benh, linmq006, mpe
On Fri, 1 Jul 2022 21:17:50 +0800, 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.
>
>
Applied to powerpc/next.
[1/1] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API
https://git.kernel.org/powerpc/c/110a1fcb6c4d55144d8179983a475f17a1d6f832
cheers
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-07-01 13:17 [PATCH] powerpc: kernel: pci_dn: Add missing of_node_put() for of_get_xx API Liang He
2022-07-01 19:47 ` Tyrel Datwyler
2022-07-01 21:36 ` Liang He
2022-07-01 22:18 ` Tyrel Datwyler
2022-09-09 12:07 ` Michael Ellerman
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