[dpdk-dev] [PATCH v2 1/2] ethdev: replace callback getting filter operations

[Andrew Rybchenko]

On 3/15/21 11:55 AM, Thomas Monjalon wrote:
> 15/03/2021 09:43, Andrew Rybchenko:
>> On 3/15/21 10:54 AM, Thomas Monjalon wrote:
>>> 15/03/2021 08:18, Andrew Rybchenko:
>>>> On 3/12/21 8:46 PM, Thomas Monjalon wrote:
>>>>> --- a/lib/librte_ethdev/rte_flow.c
>>>>> +++ b/lib/librte_ethdev/rte_flow.c
>>>>> @@ -255,18 +255,19 @@ rte_flow_ops_get(uint16_t port_id, struct rte_flow_error *error)
>>>>>  
>>>>>  	if (unlikely(!rte_eth_dev_is_valid_port(port_id)))
>>>>>  		code = ENODEV;
>>>>> -	else if (unlikely(!dev->dev_ops->filter_ctrl ||
>>>>> -			  dev->dev_ops->filter_ctrl(dev,
>>>>> -						    RTE_ETH_FILTER_GENERIC,
>>>>> -						    RTE_ETH_FILTER_GET,
>>>>> -						    &ops) ||
>>>>> -			  !ops))
>>>>> -		code = ENOSYS;
>>>>> +	else if (unlikely(dev->dev_ops->flow_ops_get == NULL))
>>>>> +		code = ENOTSUP;

It is described as:
   -ENOTSUP: valid but unsupported rule specification (e.g.
   partial bit-masks are unsupported).
So, it looks different. May be it is really better to keep
ENOSYS.

>>>>>  	else
>>>>> -		return ops;
>>>>> -	rte_flow_error_set(error, code, RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
>>>>> -			   NULL, rte_strerror(code));
>>>>> -	return NULL;
>>>>> +		code = dev->dev_ops->flow_ops_get(dev, &ops);
>>>>> +	if (code == 0 && ops == NULL)
>>>>> +		code = EACCES;
>>>> It looks something new. I think it should be mentioned in flow_ops_get
>>>> type documentation (similar to eth_promiscuous_enable_t) and
>>>> rte_flow_validate() etc functions
>>>> return values description.
>>>
>>> It is an internal function used only in rte_flow.c.
>>> The real consequence is to set rte_errno in a lot of rte_flow API.
>>> Not sure there is a good way to document the code details.
>>> Other codes are not documented in rte_flow.h
>>
>> First of all it is a behaviour of the flow_ops_get callback and
>> driver developers should know that it is a legal to return 0 and
>> ops==NULL and know what it means.
> 
> The combination code 0 and ops NULL is not new.
> Previously, it was returning ENOSYS.
> I've just given a more meaningful error code: EACCES,
> while replacing ENOSYS with ENOTSUP for the other case.

Yes, exactly. What I'm trying to say that it would be
helpful to make it a bit more transparent to PMD developers.
Yes, it was not documented before, I agree. I think it is
a good time to improve documentation.

>> Second, it is visible as rte_flow_validate() (and other functions
>> which use rte_flow_ops_get()) return value value which has
>> special meaning. So, should be documented.
> 
> Yes, I should update the API doc where ENOSYS was mentioned.
> Or probably better: I should keep the error code ENOSYS
> and do not break API.
> Preference?

Good question. I think we should not distinguish NULL callback
and NULL ops returned by not-NULL callback. So, I think
keeping ENOSYS is the best option here.