In opal_powercap_init(), of_find_compatible_node() will return
a node pointer with refcount incremented. We should use of_node_put()
in fail path or when it is not used anymore.
Besides, for_each_child_of_node() will automatically *inc* and *dec*
refcount during iteration. However, we should add the of_node_put()
if there is a break.
Signed-off-by: Liang He <[email protected]>
---
arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
index 64506b46e77b..b102477d3f95 100644
--- a/arch/powerpc/platforms/powernv/opal-powercap.c
+++ b/arch/powerpc/platforms/powernv/opal-powercap.c
@@ -153,7 +153,7 @@ void __init opal_powercap_init(void)
pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
GFP_KERNEL);
if (!pcaps)
- return;
+ goto out_powercap;
powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
if (!powercap_kobj) {
@@ -236,6 +236,9 @@ void __init opal_powercap_init(void)
kfree(pcaps[i].pg.name);
}
kobject_put(powercap_kobj);
+ of_node_put(node);
out_pcaps:
kfree(pcaps);
+out_powercap:
+ of_node_put(powercap);
}
--
2.25.1
Le 17/06/2022 à 06:20, Liang He a écrit :
> In opal_powercap_init(), of_find_compatible_node() will return
> a node pointer with refcount incremented. We should use of_node_put()
> in fail path or when it is not used anymore.
>
> Besides, for_each_child_of_node() will automatically *inc* and *dec*
> refcount during iteration. However, we should add the of_node_put()
> if there is a break.
Hi,
I'm not sure that your patch is right here. Because of this *inc* and
*dec* things, do we still need to of_node_put(powercap) once we have
entered for_each_child_of_node?
I think that this reference will be released on the first iteration of
the loop.
Maybe of_node_put(powercap) should be duplicated everywhere it is
relevant and removed from the error handling path?
Or an additional reference should be taken before the loop?
Or adding a new label with "powercap = NULL" and branching there when
needed?
CJ
>
> Signed-off-by: Liang He <[email protected]>
> ---
> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
> index 64506b46e77b..b102477d3f95 100644
> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void)
> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
> GFP_KERNEL);
> if (!pcaps)
> - return;
> + goto out_powercap;
>
> powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
> if (!powercap_kobj) {
> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void)
> kfree(pcaps[i].pg.name);
> }
> kobject_put(powercap_kobj);
> + of_node_put(node);
> out_pcaps:
> kfree(pcaps);
> +out_powercap:
> + of_node_put(powercap);
> }
At 2022-06-17 13:01:27, "Christophe JAILLET" <[email protected]> wrote:
>Le 17/06/2022 à 06:20, Liang He a écrit :
>> In opal_powercap_init(), of_find_compatible_node() will return
>> a node pointer with refcount incremented. We should use of_node_put()
>> in fail path or when it is not used anymore.
>>
>> Besides, for_each_child_of_node() will automatically *inc* and *dec*
>> refcount during iteration. However, we should add the of_node_put()
>> if there is a break.
>
>Hi,
>
>I'm not sure that your patch is right here. Because of this *inc* and
>*dec* things, do we still need to of_node_put(powercap) once we have
>entered for_each_child_of_node?
>
>I think that this reference will be released on the first iteration of
>the loop.
>
Hi, CJ,
Thanks for your reply and I want have a discuss.
Based on my review on the src of 'of_get_next_child', there is only
*inc* for next and *dec* for pre as follow.
(|node| == powercap)
======__of_get_next_child( |node|, prev)======
...
next = prev? prev->sibling:|node|->child;
of_node_get(next);
of_node_put(prev);
...
=========================
However, there is no any code to release the |node| (i.e., *powercap*).
Am I right? If I am wrong, please correct me, thanks.
>
>Maybe of_node_put(powercap) should be duplicated everywhere it is
>relevant and removed from the error handling path?
>Or an additional reference should be taken before the loop?
>Or adding a new label with "powercap = NULL" and branching there when
>needed?
>
>CJ
If my understanding is right, I think current patch is right.
Otherwise, I will make a new patch to handle that, Thanks.
Liang
>
>>
>> Signed-off-by: Liang He <[email protected]>
>> ---
>> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
>> index 64506b46e77b..b102477d3f95 100644
>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
>> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void)
>> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
>> GFP_KERNEL);
>> if (!pcaps)
>> - return;
>> + goto out_powercap;
>>
>> powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
>> if (!powercap_kobj) {
>> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void)
>> kfree(pcaps[i].pg.name);
>> }
>> kobject_put(powercap_kobj);
>> + of_node_put(node);
>> out_pcaps:
>> kfree(pcaps);
>> +out_powercap:
>> + of_node_put(powercap);
>> }
At 2022-06-17 13:01:27, "Christophe JAILLET" <[email protected]> wrote:
>Le 17/06/2022 à 06:20, Liang He a écrit :
>> In opal_powercap_init(), of_find_compatible_node() will return
>> a node pointer with refcount incremented. We should use of_node_put()
>> in fail path or when it is not used anymore.
>>
>> Besides, for_each_child_of_node() will automatically *inc* and *dec*
>> refcount during iteration. However, we should add the of_node_put()
>> if there is a break.
>
>Hi,
>
>I'm not sure that your patch is right here. Because of this *inc* and
>*dec* things, do we still need to of_node_put(powercap) once we have
>entered for_each_child_of_node?
>
>I think that this reference will be released on the first iteration of
>the loop.
>
>
>Maybe of_node_put(powercap) should be duplicated everywhere it is
>relevant and removed from the error handling path?
>Or an additional reference should be taken before the loop?
>Or adding a new label with "powercap = NULL" and branching there when
>needed?
>
>CJ
>
>>
>> Signed-off-by: Liang He <[email protected]>
>> ---
>> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
>> index 64506b46e77b..b102477d3f95 100644
>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
>> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void)
>> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
>> GFP_KERNEL);
>> if (!pcaps)
>> - return;
>> + goto out_powercap;
>>
>> powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
>> if (!powercap_kobj) {
>> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void)
>> kfree(pcaps[i].pg.name);
>> }
>> kobject_put(powercap_kobj);
>> + of_node_put(node);
>> out_pcaps:
>> kfree(pcaps);
>> +out_powercap:
>> + of_node_put(powercap);
>> }
Hi, CJ.
I think my patch is correct based on the old commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.19-rc2&id=09700c504d8e63faffd2a2235074e8c5d130cb8f
Bugs and fix solutions in this 09700c504d8e63-commit are very similar with mine.
Besides, I also find similar new bugs in other two files in the same directory 'powernv',
so I have merged all three files' patches into one commit. '[PATCH v2] powerpc: powernv: Fix refcount leak bug'.
Thanks.
Liang
Le 17/06/2022 à 07:42, Liang He a écrit :
>
>
>
> At 2022-06-17 13:01:27, "Christophe JAILLET" <[email protected]> wrote:
>> Le 17/06/2022 à 06:20, Liang He a écrit :
>>> In opal_powercap_init(), of_find_compatible_node() will return
>>> a node pointer with refcount incremented. We should use of_node_put()
>>> in fail path or when it is not used anymore.
>>>
>>> Besides, for_each_child_of_node() will automatically *inc* and *dec*
>>> refcount during iteration. However, we should add the of_node_put()
>>> if there is a break.
>>
>> Hi,
>>
>> I'm not sure that your patch is right here. Because of this *inc* and
>> *dec* things, do we still need to of_node_put(powercap) once we have
>> entered for_each_child_of_node?
>>
>> I think that this reference will be released on the first iteration of
>> the loop.
>>
>
> Hi, CJ,
>
> Thanks for your reply and I want have a discuss.
>
> Based on my review on the src of 'of_get_next_child', there is only
> *inc* for next and *dec* for pre as follow.
>
> (|node| == powercap)
> ======__of_get_next_child( |node|, prev)======
> ...
> next = prev? prev->sibling:|node|->child;
> of_node_get(next);
> of_node_put(prev);
> ...
> =========================
>
> However, there is no any code to release the |node| (i.e., *powercap*).
>
> Am I right? If I am wrong, please correct me, thanks.
You are right.
I mis-read __of_get_next_child(().
CJ
>
>>
>> Maybe of_node_put(powercap) should be duplicated everywhere it is
>> relevant and removed from the error handling path?
>> Or an additional reference should be taken before the loop?
>> Or adding a new label with "powercap = NULL" and branching there when
>> needed?
>>
>> CJ
>
> If my understanding is right, I think current patch is right.
>
> Otherwise, I will make a new patch to handle that, Thanks.
>
> Liang
>
>>
>>>
>>> Signed-off-by: Liang He <[email protected]>
>>> ---
>>> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
>>> index 64506b46e77b..b102477d3f95 100644
>>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
>>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
>>> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void)
>>> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps),
>>> GFP_KERNEL);
>>> if (!pcaps)
>>> - return;
>>> + goto out_powercap;
>>>
>>> powercap_kobj = kobject_create_and_add("powercap", opal_kobj);
>>> if (!powercap_kobj) {
>>> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void)
>>> kfree(pcaps[i].pg.name);
>>> }
>>> kobject_put(powercap_kobj);
>>> + of_node_put(node);
>>> out_pcaps:
>>> kfree(pcaps);
>>> +out_powercap:
>>> + of_node_put(powercap);
>>> }