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

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Nov 17, 2015 at 07:53:09AM -0800, Stephen Hemminger wrote:
> 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.

Ok, so assuming we care about the ABI for debug builds, is it enough to just
push a patch with a deprecation notice for this for 2.2, or do I need to see about
doing a new patchset with the NEXT_ABI macros included in it? My preference is
obviously for the former.

/Bruce