Re: [XEN PATCH v2] x86: p2m-pod: address violation of MISRA C Rule 2.1

[Jan Beulich <jbeulich@xxxxxxxx>]

On 10.09.2024 11:53, Nicola Vetrini wrote:
> On 2024-09-10 11:08, Jan Beulich wrote:
>> On 10.09.2024 10:56, Nicola Vetrini wrote:
>>> On 2024-07-01 10:36, Jan Beulich wrote:
>>>> On 28.06.2024 08:30, Nicola Vetrini wrote:
>>>> This being about unreachable code, why are the domain_crash() not the
>>>> crucial points of "unreachability"? And even if they weren't there, 
>>>> why
>>>> wouldn't it be the goto or ...
>>>>
>>>>> --- a/xen/arch/x86/mm/p2m-pod.c
>>>>> +++ b/xen/arch/x86/mm/p2m-pod.c
>>>>> @@ -1040,6 +1040,7 @@ out_unmap:
>>>>>       * Something went wrong, probably crashing the domain.  Unmap
>>>>>       * everything and return.
>>>>>       */
>>>>> +    /* SAF-8-safe Rule 2.1: defensive programming */
>>>>>      for ( i = 0; i < count; i++ )
>>>>>          if ( map[i] )
>>>>>              unmap_domain_page(map[i]);
>>>>
>>>> ... the label (just out of context) where the comment needs to go?
>>>
>>> Because of the way this rule's configuration work, deviations are 
>>> placed
>>> on the construct that ends up being the target of the unreachability,
>>
>> What's "target" here? What if this loop was removed from the function?
>> Then both the label and the domain_crash() invocations would still be
>> unreachable in debug builds. Are you telling me that this then wouldn't
>> be diagnosed by Eclair? Or that it would then consider the closing
>> figure brace of the function "the target of the unreachability"?
> 
> Exactly, the end brace is a target to which the "function end" construct 
> is associated.
> It would be kind of strange, though: why not just doing "domain_crash(); 
> return;" in that case?

Sure, the question was theoretical. Now if "return" was used directly
there, what would then be the "target"? IOW - the more abstract question
of my earlier reply still wasn't answered.

Jan