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

[Thomas Monjalon <thomas@monjalon.net>]

15/03/2021 10:08, 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.

OK, thank you for the review.
So the conclusion is: keep ENOSYS and document NULL ops case.