Re: [dpdk-dev] [PATCH v3 1/2] ethdev: queue release callback optional

["Xueming(Steven) Li" <xuemingl@nvidia.com>]

On Fri, 2021-09-17 at 14:53 +0300, Andrew Rybchenko wrote:
> On 9/17/21 2:29 PM, Andrew Rybchenko wrote:
> > On 9/17/21 12:39 PM, Xueming Li wrote:
> > > Some drivers don't need Rx and Tx queue release callback, make it
> > > optional.
> > > 
> > > Signed-off-by: Xueming Li <xuemingl@nvidia.com>
> > 
> > LGTM, but please, consider one nit below
> > 
> > Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> > 
> > > ---
> > >  lib/ethdev/rte_ethdev.c | 48 +++++++++++++++++------------------------
> > >  1 file changed, 20 insertions(+), 28 deletions(-)
> > > 
> > > diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> > > index daf5ca9242..2f316d1646 100644
> > > --- a/lib/ethdev/rte_ethdev.c
> > > +++ b/lib/ethdev/rte_ethdev.c
> > > @@ -905,12 +905,11 @@ eth_dev_rx_queue_config(struct rte_eth_dev *dev, uint16_t nb_queues)
> > >  			return -(ENOMEM);
> > >  		}
> > >  	} else if (dev->data->rx_queues != NULL && nb_queues != 0) { /* re-configure */
> > > -		RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_release, -ENOTSUP);
> > > -
> > >  		rxq = dev->data->rx_queues;
> > >  
> > > -		for (i = nb_queues; i < old_nb_queues; i++)
> > > -			(*dev->dev_ops->rx_queue_release)(rxq[i]);
> > > +		if (dev->dev_ops->rx_queue_release != NULL)
> > > +			for (i = nb_queues; i < old_nb_queues; i++)
> > > +				(*dev->dev_ops->rx_queue_release)(rxq[i]);
> > 
> > Since 'if' body has more than one line, I'd add curly brackets
> > around to make it a bit easier to read and more robust against
> > future changes.
> > 
> > Similar note is applicable to many similar cases in the patch.
> > 
> 
> Reviewed the next patch I realize one thing:
> Who is responsible for setting dev->data->rxq[rx_queue_id] to
> NULL if release callback is not specified. IMHO, it is
> inconsistent to keep it filled in after release. I think that
> the generic code in ethdev must care about it regardless
> callback presence. It means that we need helper function
> which cares about it in single place. Also it means that
> we can't optimize loops like this. We need the loop anyway
> to set all queue pointers to NULL.

Yes, a dedicate function make things more clear, thanks! updated in v4.