Re: [Qemu-devel] [PATCH v1 03/11] s390x: store cpu states inside machine state

[Thomas Huth]

On 31.08.2017 16:36, David Hildenbrand wrote:
> On 31.08.2017 16:31, Thomas Huth wrote:
>> On 31.08.2017 16:23, David Hildenbrand wrote:
>>>
>>>>> +struct S390CPU;
>>>>
>>>> You define a "struct S390CPU" here ...
>>>>
>>>>>  typedef struct S390CcwMachineState {
>>>>>      /*< private >*/
>>>>>      MachineState parent_obj;
>>>>>  
>>>>>      /*< public >*/
>>>>> +    S390CPU **cpus;
>>>>
>>>> ... but use the typedef'ed S390CPU here ... looks somewhat suspicious, I
>>>> wonder whether the typedef is really in the right place?
>>>
>>> General question: how much do we care about headers that are not consistent?
>>>
>>> E.g. shall I forward declare or simply ignore if compilers don't bite me?
>>
>> My remark was not so much about your patch, but about the original
>> definition instead: "struct S390CPU" is declared in target/s390x/cpu.h,
>> but "typedef struct S390CPU S390CPU" is in target/s390x/cpu-qom.h. I
>> think they should rather be declared in the same header file instead. Or
> 
> I agree, will have a look.
> 
>> your "struct S390CPU;" forward declaration should go into cpu-qom.h
>> instead, right in front of the typedef.
>>
> 
> Let me rephrase my question:
> 
> include/hw/s390x/s390-virtio-ccw.h does not include cpu.h/cpu-qom.h
> 
> If compilers don't complain, do we have to forward declare at all? (I
> think it is cleaner, but I would like to know what is suggested)

Well, doing a forward declaration with "struct S390CPU;" and then using
the typedef'd "S390CPU" without "struct" does not make much sense -
these are two "different" types. If you can use "S390CPU" here without
the "struct S390CPU;" declaration, that means the cpu-qom.h header got
included indirectly already - so I'd suggest to simply remove the
"struct S390CPU;" forward declaration from your patch.

 Thomas