Re: [dpdk-dev] [PATCH] eventdev: Add rte_errno return values to the enqueue and dequeue functions

["Eads, Gage" <gage.eads@intel.com>]

>  -----Original Message-----
>  From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
>  Sent: Monday, February 13, 2017 10:10 PM
>  To: Eads, Gage <gage.eads@intel.com>
>  Cc: dev@dpdk.org; Richardson, Bruce <bruce.richardson@intel.com>;
>  hemant.agrawal@nxp.com; Van Haaren, Harry <harry.van.haaren@intel.com>;
>  nipun.gupta@nxp.com
>  Subject: Re: [PATCH] eventdev: Add rte_errno return values to the enqueue and
>  dequeue functions
>  
>  On Fri, Feb 10, 2017 at 03:02:21PM -0600, Gage Eads wrote:
>  > This change allows user software to differentiate between an invalid
>  > argument (such as an invalid queue_id or sched_type in an enqueued
>  > event) and backpressure from the event device.
>  >
>  > The port and device ID checks are placed in RTE_LIBRTE_EVENTDEV_DEBUG
>  > header guards to avoid the performance hit in non-debug execution.
>  >
>  > Signed-off-by: Gage Eads <gage.eads@intel.com>
>  > ---
>  >  static inline uint16_t
>  > @@ -1127,6 +1133,21 @@ rte_event_enqueue_burst(uint8_t dev_id, uint8_t
>  > port_id,  {
>  >  	struct rte_eventdev *dev = &rte_eventdevs[dev_id];
>  >
>  > +	rte_errno = 0;
>  
>  I don't think it is required.  If at all required, move this under
>  RTE_LIBRTE_EVENTDEV_DEBUG to save store to rte_errno cycles on fastpath

Agreed -- if we encounter an error we should set rte_errno, otherwise the return value will equal nb_events and the user shouldn't check it.

Will fix in v2.

>  
>  > +#ifdef RTE_LIBRTE_EVENTDEV_DEBUG
>  > +	if (rte_eventdevs[dev_id].attached == RTE_EVENTDEV_DETACHED) {
>  > +		RTE_EDEV_LOG_DEBUG("Invalid dev_id=%d\n", dev_id);
>  > +		rte_errno = -EINVAL;
>  > +		return 0;
>  > +	}
>  > +
>  > +	if (port_id >= dev->data->nb_ports) {
>  > +		RTE_EDEV_LOG_DEBUG("Invalid port_id=%d\n", port_id);
>  > +		rte_errno = -EINVAL;
>  > +		return 0;
>  > +	}
>  > +#endif
>  > +
>  >  	/*
>  >  	 * Allow zero cost non burst mode routine invocation if application
>  >  	 * requests nb_events as const one
>  > @@ -1235,6 +1256,21 @@ rte_event_dequeue_burst(uint8_t dev_id, uint8_t
>  > port_id, struct rte_event ev[],  {
>  >  	struct rte_eventdev *dev = &rte_eventdevs[dev_id];
>  >
>  > +#ifdef RTE_LIBRTE_EVENTDEV_DEBUG
>  > +	rte_errno = 0;
>  > +	if (rte_eventdevs[dev_id].attached == RTE_EVENTDEV_DETACHED) {
>  > +		RTE_EDEV_LOG_DEBUG("Invalid dev_id=%d\n", dev_id);
>  > +		rte_errno = -EINVAL;
>  > +		return 0;
>  > +	}
>  > +
>  > +	if (port_id >= dev->data->nb_ports) {
>  > +		RTE_EDEV_LOG_DEBUG("Invalid port_id=%d\n", port_id);
>  > +		rte_errno = -EINVAL;
>  > +		return 0;
>  > +	}
>  > +#endif
>  > +
>  >  	/*
>  >  	 * Allow zero cost non burst mode routine invocation if application
>  >  	 * requests nb_events as const one
>  > --
>  > 2.7.4
>  >