Re: [dpdk-dev] [PATCH] net/virtio: remove handling of zero desc number on RxQ setup

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 8/20/21 2:47 PM, Andrew Rybchenko wrote:
> From: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
> 
> Rx queue setup callback allows to use the whole ring when
> descriptor number argument equals zero. There's no point to
> handle zero in any way since RTE Rx queue setup function
> rte_eth_rx_queue_setup() doesn't pass zero using fallback
> values.
> 
> Fixes: 3be82f5cc5e3 ("ethdev: support PMD-tuned Tx/Rx parameters")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> ---
>  drivers/net/virtio/virtio_rxtx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 8a48fba5cc..18f03c9fc9 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -706,7 +706,7 @@ virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
>  	}
>  	vq->vq_free_thresh = rx_free_thresh;
>  
> -	if (nb_desc == 0 || nb_desc > vq->vq_nentries)
> +	if (nb_desc > vq->vq_nentries)
>  		nb_desc = vq->vq_nentries;
>  	vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);
>  
> 

Is that really a fix?
I see it more like an optimization in a cold path, so maybe it is not
worth backporting?

Other than that:
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime