Re: [dpdk-dev] [PATCH v1] devtools: update abi ignore for cryptodev

[Dodji Seketeli <dodji@redhat.com>]

"Kinsella, Ray" <mdr@ashroe.eu> writes:

> On 22/01/2021 13:09, Dodji Seketeli wrote:
>> Thomas Monjalon <thomas@monjalon.net> writes:
>> 
>> [...]
>> 
>>>>> Then I've added (quickly) a libabigail exception rule:
>>>>>
>>>>> [suppress_type]
>>>>> 	name = rte_cryptodev
>>>>> 	has_data_member_inserted_between = {0, 1023}
>>>>>
>>>>> Now we want to improve this rule to restrict the offsets
>>>>> to the padding at the end of the struct only,
>>>>> so we keep forbidding changes in existing fields,
>>>>> and forbidding additions further the current struct size.
>>>>> Is this new rule good?
>>>>>
>>>>> 	has_data_member_inserted_between = {offset_after(attached), end}
>>>>
>>>>
>>>> Yes, this rule should do what you think it says.
>>>>
>>>>> Do you confirm that the keyword "end" means the old reference size?
>>>>
>>>> Yes I do.
>>>>
>>>>
>>>>> What else do we need to check for adding a new field in a padding?
>>>>
>>>> Actually, that rule will work independantly of it there is enough
>>>> padding or not.  It'll shut down the change report, even if the added
>>>> data exceeds the padding.
>>>
>>> I don't understand why.
>>> If "end" means the old reference size, then addition after the old size
>>> should be reported, isn't it?
>> 
>> Yes, you are right.
>> 
>> What I meant is that even if (in an hypothetical case, not yours) the
>> padding was so "small" that it wasn't going up to the 'end' of the
>> struct, that rule would have still shut down the change report.
>
> Understood - you are talking about padding between members.

Exactly.

Cheers,

-- 
		Dodji