Re: Re: [PATCH 5/5] powerpc/8xx: fix possible object reference leak

Re: Re: [PATCH 5/5] powerpc/8xx: fix possible object reference leak

[wen.yang99]

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Hi, Christophe,

>> The call to of_find_compatible_node returns a node pointer with refcount
>> incremented thus it must be explicitly decremented after the last
>> usage.
>> irq_domain_add_linear also calls of_node_get to increase refcount,
>> so irq_domain will not be affected when it is released.
>
>
> Should you have a:
>
> Fixes: a8db8cf0d894 ("irq_domain: Replace irq_alloc_host() with
> revmap-specific initializers")
>
> If not, it means your change is in contradiction with commit
> b1725c9319aa ("[POWERPC] arch/powerpc/sysdev: Add missing of_node_put")

Thank you very much.
This problem existed before this commit (a8db8cf0d894).
and the SmPL we used is:
https://lkml.org/lkml/2019/3/14/880
We are still improving this SmPL, and it is somewhat different from the script 
used by b1725c9319aa ("[POWERPC] arch/powerpc/sysdev: Add missing of_node_put").

>> Detected by coccinelle with the following warnings:
>> ./arch/powerpc/platforms/8xx/pic.c:158:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 136, but without a corresponding object release within this function.
>>
>>   arch/powerpc/platforms/8xx/pic.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/powerpc/platforms/8xx/pic.c b/arch/powerpc/platforms/8xx/pic.c
>> index 8d5a25d..13d880b 100644
>> --- a/arch/powerpc/platforms/8xx/pic.c
>> +++ b/arch/powerpc/platforms/8xx/pic.c
>> @@ -155,6 +155,7 @@ int mpc8xx_pic_init(void)
>>           ret = -ENOMEM;
>>           goto out;
>>       }
>> +    of_node_put(np);
>>       return 0;
>>
>>   out:
>>
>
> I guess it would be better as follows:
> 
> --- a/arch/powerpc/platforms/8xx/pic.c
> +++ b/arch/powerpc/platforms/8xx/pic.c
> @@ -153,9 +153,7 @@ int mpc8xx_pic_init(void)
> if (mpc8xx_pic_host == NULL) {
> printk(KERN_ERR "MPC8xx PIC: failed to allocate irq
> host!\n");
> ret = -ENOMEM;
> -               goto out;
> }
> -       return 0;
> 
> out:
> of_node_put(np);

OK.
Thank you.
We will fix it soon.

Thanks and regards,
Wen