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

[Thomas Monjalon <thomas@monjalon.net>]

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;
> >>>  	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.

> 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?