Re: [PATCH v2 5/7] x86: generalize padding field handling

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.07.2020 10:34, Roger Pau Monné wrote:
> On Wed, Jul 15, 2020 at 08:36:10AM +0200, Jan Beulich wrote:
>> On 14.07.2020 16:29, Roger Pau Monné wrote:
>>> On Wed, Jul 01, 2020 at 12:27:37PM +0200, Jan Beulich wrote:
>>>> --- a/xen/common/compat/memory.c
>>>> +++ b/xen/common/compat/memory.c
>>>> @@ -354,10 +354,13 @@ int compat_memory_op(unsigned int cmd, X
>>>>                  return -EFAULT;
>>>>  
>>>>  #define XLAT_vnuma_topology_info_HNDL_vdistance_h(_d_, _s_)               
>>>> \
>>>> +            case XLAT_vnuma_topology_info_vdistance_pad:                \
>>>>              guest_from_compat_handle((_d_)->vdistance.h, 
>>>> (_s_)->vdistance.h)
>>>>  #define XLAT_vnuma_topology_info_HNDL_vcpu_to_vnode_h(_d_, _s_)           
>>>> \
>>>> +            case XLAT_vnuma_topology_info_vcpu_to_vnode_pad:            \
>>>>              guest_from_compat_handle((_d_)->vcpu_to_vnode.h, 
>>>> (_s_)->vcpu_to_vnode.h)
>>>>  #define XLAT_vnuma_topology_info_HNDL_vmemrange_h(_d_, _s_)               
>>>> \
>>>> +            case XLAT_vnuma_topology_info_vmemrange_pad:                \
>>>>              guest_from_compat_handle((_d_)->vmemrange.h, 
>>>> (_s_)->vmemrange.h)
>>>
>>> I find this quite ugly, would it be better to just handle them with a
>>> default case in the XLAT_ macros?
>>
>> Default cases explicitly do not get added to be able to spot missing
>> case labels, as most compilers will warn about such when the controlling
>> expression is of enum type.
> 
> As you say on the comment above, ignoring those for translation
> macros would be better, and would avoid the ugliness of having to add
> the _pad cases here.

Ah, yes, if the supposed adjustment would also suppress the generation
of respective enumerators.

Jan