[dpdk-dev] [PATCH v5 3/3] ethdev: fix wrong error return refere to API definition

[Liang, Cunming]

Ok, I'll roll back to v4.

> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Friday, October 24, 2014 7:05 PM
> To: dev at dpdk.org
> Cc: nhorman at tuxdriver.com; Richardson, Bruce; De Lara Guarch, Pablo; Liang,
> Cunming
> Subject: RE: [PATCH v5 3/3] ethdev: fix wrong error return refere to API definition
> 
> 
> 
> > -----Original Message-----
> > From: y at ecsmtp.sh.intel.com [mailto:y at ecsmtp.sh.intel.com]
> > Sent: Friday, October 24, 2014 6:55 AM
> > To: dev at dpdk.org
> > Cc: nhorman at tuxdriver.com; Richardson, Bruce; Ananyev, Konstantin; De Lara
> Guarch, Pablo; Liang, Cunming
> > Subject: [PATCH v5 3/3] ethdev: fix wrong error return refere to API definition
> >
> > From: Cunming Liang <cunming.liang at intel.com>
> >
> > Per definition, rte_eth_rx_burst/rte_eth_tx_burst/rte_eth_rx_queue_count
> returns the packet number.
> > When RTE_LIBRTE_ETHDEV_DEBUG turns on, retval of FUNC_PTR_OR_ERR_RTE
> was set to -ENOTSUP.
> > It makes confusing.
> > The patch always return 0 no matter no packet or there's error.
> > Meanwhile set errno in such kind of checking.
> >
> > Signed-off-by: Cunming Liang <cunming.liang at intel.com>
> > ---
> >  lib/librte_ether/rte_ethdev.c |   10 +++++++---
> >  1 files changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> > index 50f10d9..6675f28 100644
> > --- a/lib/librte_ether/rte_ethdev.c
> > +++ b/lib/librte_ether/rte_ethdev.c
> > @@ -81,12 +81,14 @@
> >  /* Macros for checking for restricting functions to primary instance only */
> >  #define PROC_PRIMARY_OR_ERR_RET(retval) do { \
> >  	if (rte_eal_process_type() != RTE_PROC_PRIMARY) { \
> > +		rte_errno = -E_RTE_SECONDARY;				\
> >  		PMD_DEBUG_TRACE("Cannot run in secondary processes\n"); \
> >  		return (retval); \
> >  	} \
> >  } while(0)
> >  #define PROC_PRIMARY_OR_RET() do { \
> >  	if (rte_eal_process_type() != RTE_PROC_PRIMARY) { \
> > +		rte_errno = -E_RTE_SECONDARY;				\
> >  		PMD_DEBUG_TRACE("Cannot run in secondary processes\n"); \
> >  		return; \
> >  	} \
> > @@ -95,12 +97,14 @@
> >  /* Macros to check for invlaid function pointers in dev_ops structure */
> >  #define FUNC_PTR_OR_ERR_RET(func, retval) do { \
> >  	if ((func) == NULL) { \
> > +		rte_errno = -ENOTSUP; \
> >  		PMD_DEBUG_TRACE("Function not supported\n"); \
> >  		return (retval); \
> >  	} \
> >  } while(0)
> >  #define FUNC_PTR_OR_RET(func) do { \
> >  	if ((func) == NULL) { \
> > +		rte_errno = -ENOTSUP; \
> >  		PMD_DEBUG_TRACE("Function not supported\n"); \
> >  		return; \
> >  	} \
> > @@ -2530,7 +2534,7 @@ rte_eth_rx_burst(uint8_t port_id, uint16_t
> queue_id,
> >  		return 0;
> >  	}
> >  	dev = &rte_eth_devices[port_id];
> > -	FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, -ENOTSUP);
> > +	FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, 0);
> >  	if (queue_id >= dev->data->nb_rx_queues) {
> >  		PMD_DEBUG_TRACE("Invalid RX queue_id=%d\n", queue_id);
> >  		return 0;
> > @@ -2551,7 +2555,7 @@ rte_eth_tx_burst(uint8_t port_id, uint16_t
> queue_id,
> >  	}
> >  	dev = &rte_eth_devices[port_id];
> >
> > -	FUNC_PTR_OR_ERR_RET(*dev->tx_pkt_burst, -ENOTSUP);
> > +	FUNC_PTR_OR_ERR_RET(*dev->tx_pkt_burst, 0);
> >  	if (queue_id >= dev->data->nb_tx_queues) {
> >  		PMD_DEBUG_TRACE("Invalid TX queue_id=%d\n", queue_id);
> >  		return 0;
> > @@ -2570,7 +2574,7 @@ rte_eth_rx_queue_count(uint8_t port_id, uint16_t
> queue_id)
> >  		return 0;
> >  	}
> >  	dev = &rte_eth_devices[port_id];
> > -	FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_count, -ENOTSUP);
> > +	FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_count, 0);
> >  	return (*dev->dev_ops->rx_queue_count)(dev, queue_id);
> >  }
> 
> There are few things that worry me with that approach:
> 
> 1.  Different behaviour of rte_eth_rx_burst/rte_eth_tx_burst  for
> RTE_LIBRTE_ETHDEV_DEBUG switched on/off.
> So application might need to differentiate its code depending on
> RTE_LIBRTE_ETHDEV_DEBUG value.
> 
> 2. Even for RTE_LIBRTE_ETHDEV_DEBUG is on the behaviour of rte_eth_rx_burst/
> rte_eth_tx_burst will be inconsistent:
> It sets rte_errno if dev->rx_pkt_burst == NULL, but doesn't do the same for other
> error conditions:
> When port_id or queue_id is invalid.
> 
> 3. Modifying FUNC_PTR_OR_ERR_RET() to set rte_errno, we make behaviour of
> other rte_ethdev functions inconsistent too:
> Now for some error conditions they do set rte_errno, for others they don't.
> 
> So if it would be me, I'll just:
> - leave FUNC_PTR_OR_*_RET unmodified.
> - changes rte_eth_rx_burst/tx_burst for RTE_LIBRTE_ETHDEV_DEBUG something
> like:
> 
> - FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, -ENOTSUP);
> + FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, 0);
> 
> I think, that just error logging is enough here.
> 
> Konstantin
> 
> >
> > --
> > 1.7.4.1