Re: [XEN PATCH v3 01/16] misra: add deviation for headers that explicitly avoid guards

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.03.2024 23:55, Stefano Stabellini wrote:
> On Mon, 11 Mar 2024, Jan Beulich wrote:
>> On 11.03.2024 09:59, Simone Ballarin wrote:
>>> Some headers, under specific circumstances (documented in a comment at
>>> the beginning of the file), explicitly avoid inclusion guards: the caller
>>> is responsible for including them correctly.
>>>
>>> These files are not supposed to comply with Directive 4.10:
>>> "Precautions shall be taken in order to prevent the contents of a header
>>> file being included more than once"
>>>
>>> This patch adds deviation cooments for headers that avoid guards.
>>>
>>> Signed-off-by: Simone Ballarin <simone.ballarin@xxxxxxxxxxx>
>>>
>>> ---
>>> Changes in v3:
>>> - fix inconsistent deviation ID
>>> - change comment-based deviation text
>>> Changes in v2:
>>> - use the format introduced with doc/misra/safe.json instead of
>>>   a generic text-based deviation
>>> ---
>>>  docs/misra/safe.json                        | 9 +++++++++
>>>  xen/include/public/arch-x86/cpufeatureset.h | 1 +
>>>  xen/include/public/errno.h                  | 1 +
>>>  3 files changed, 11 insertions(+)
>>
>> I understand something wants doing, but having such comments appear in public
>> headers feels wrong to me. I'm afraid I have no good alternative suggestion.
> 
> Given that in both cases there is very nice explanation on how to use
> the headers as an in-code comment just above, could we embed the
> SAF-3-safe marker in the existing comment?

I'm afraid that won't address my remark, and I'm further afraid this would
then render the SAF part of the comment ineffectual.

> If not, I think we should go with this patch as is (I don't think it is
> worth my, your, and Simone's time to look for alternatives).

Easy alternative: Simply leave public headers alone.

Jan