Re: [Xen-devel] [PATCH v1] x86/mm: Clean up p2m_finish_type_change return value

[Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>]

On 16.01.2019 17:39, Jan Beulich wrote:
>>>> On 16.01.19 at 16:13, <aisaila@xxxxxxxxxxxxxxx> wrote:
>> Changed the return value of 1 to 0 so now p2m_finish_type_change returns
>> 0 for success or <0 for error.
> 
> This is a valid alternative return value model. Both have their merits.
> Hence if you want to change from one to the other, you should give
> a reason.

This was done after a discussion with George 
https://lists.xenproject.org/archives/html/xen-devel/2019-01/msg00740.html

I will update the patch comment with this reason.
> 
>> --- a/xen/arch/x86/mm/p2m.c
>> +++ b/xen/arch/x86/mm/p2m.c
>> @@ -1178,6 +1178,7 @@ int p2m_finish_type_change(struct domain *d,
>>   
>>       if ( rc < 0 )
>>           goto out;
>> +    rc = 0;
> 
> Instead of this and ...
> 
>> @@ -1188,19 +1189,14 @@ int p2m_finish_type_change(struct domain *d,
>>               if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
>>               {
>>                   struct p2m_domain *altp2m = d->arch.altp2m_p2m[i];
>> -                int rc1;
>>   
>>                   p2m_lock(altp2m);
>> -                rc1 = finish_type_change(altp2m, first_gfn, max_nr);
>> +                rc = finish_type_change(altp2m, first_gfn, max_nr);
>>                   p2m_unlock(altp2m);
>>   
>> -                if ( rc1 < 0 )
>> -                {
>> -                    rc = rc1;
>> +                if ( rc < 0 )
>>                       goto out;
>> -                }
>> -
>> -                rc |= rc1;
>> +                rc = 0;
> 
> ... this, why don't you simply set "rc" to zero once ...
> 
>>               }
>>       }
>>   #endif
> 
> ... below here (but ahead of the "out" label)?

I will move the rc = 0 there in v2.

Thanks,
Alex

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