Re: [XEN PATCH v2 2/3] xen/gnttab: address a violation of MISRA C Rule 13.6

[Jan Beulich <jbeulich@xxxxxxxx>]

On 01.10.2024 00:53, Stefano Stabellini wrote:
> On Mon, 30 Sep 2024, Federico Serafini wrote:
>> --- a/xen/common/compat/grant_table.c
>> +++ b/xen/common/compat/grant_table.c
>> @@ -78,12 +78,15 @@ int compat_grant_table_op(
>>          cmd_op = cmd;
>>      switch ( cmd_op )
>>      {
>> -#define CASE(name) \
>> -    case GNTTABOP_##name: \
>> -        if ( unlikely(!guest_handle_okay(guest_handle_cast(uop, \
>> -                                                           
>> gnttab_##name##_compat_t), \
>> -                                         count)) ) \
>> -            rc = -EFAULT; \
>> +#define CASE(name)                                                  \
>> +    case GNTTABOP_ ## name:                                         \
>> +    {                                                               \
>> +        XEN_GUEST_HANDLE_PARAM(gnttab_ ## name ## _compat_t) h =    \
>> +            guest_handle_cast(uop, gnttab_ ## name ## _compat_t);   \
>> +                                                                    \
>> +        if ( unlikely(!guest_handle_okay(h, count)) )               \
>> +            rc = -EFAULT;                                           \
>> +    }                                                               \
>>          break
> 
> We would typically put the break within the case { }

That won't work very well with the break not having a semicolon, for the
semicolon to actually be used when invoking the macro. Moving the break
(while adding a semicolon there) as you suggest would then mean the use
site semicolon to end up being an unreachable statement.

Jan