Re: [dpdk-dev] [PATCH v4 2/2] ethdev: add sanity checks to functions

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 17 Nov 2015 12:21:07 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:

> The functions rte_eth_rx_queue_count and rte_eth_descriptor_done are
> supported by very few PMDs. Therefore, it is best to check for support
> for the functions in the ethdev library, so as to avoid run-time crashes
> at run-time if the application goes to use those APIs. Similarly, the
> port parameter should also be checked for validity.
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> 
> ---
>  lib/librte_ether/rte_ethdev.h | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index a00cd46..028be59 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -2533,16 +2533,16 @@ rte_eth_rx_burst(uint8_t port_id, uint16_t queue_id,
>   * @param queue_id
>   *  The queue id on the specific port.
>   * @return
> - *  The number of used descriptors in the specific queue.
> + *  The number of used descriptors in the specific queue, or:
> + *     (-EINVAL) if *port_id* is invalid
> + *     (-ENOTSUP) if the device does not support this function
>   */
> -static inline uint32_t
> +static inline int
>  rte_eth_rx_queue_count(uint8_t port_id, uint16_t queue_id)
>  {
>  	struct rte_eth_dev *dev = &rte_eth_devices[port_id];
> -#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> -	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, 0);
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_count, 0);
> -#endif
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -EINVAL);
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_count, -ENOTSUP);
>          return (*dev->dev_ops->rx_queue_count)(dev, queue_id);
>  }
>  
> @@ -2559,15 +2559,14 @@ rte_eth_rx_queue_count(uint8_t port_id, uint16_t queue_id)
>   *  - (1) if the specific DD bit is set.
>   *  - (0) if the specific DD bit is not set.
>   *  - (-ENODEV) if *port_id* invalid.
> + *  - (-ENOTSUP) if the device does not support this function
>   */
>  static inline int
>  rte_eth_rx_descriptor_done(uint8_t port_id, uint16_t queue_id, uint16_t offset)
>  {
>  	struct rte_eth_dev *dev = &rte_eth_devices[port_id];
> -#ifdef RTE_LIBRTE_ETHDEV_DEBUG
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>  	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_descriptor_done, -ENOTSUP);
> -#endif
>  	return (*dev->dev_ops->rx_descriptor_done)( \
>  		dev->data->rx_queues[queue_id], offset);
>  }

This breaks ABI since older application built with debug will try
and find the shared library entry for the routine.