Re: [dpdk-dev] [PATCH] net/hns3: fix checking enough Tx BDs

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 11/25/2019 9:00 AM, Wei Hu (Xavier) wrote:
> From: "Wei Hu (Xavier)" <xavier.huwei@huawei.com>
> 
> In .tx_pkt_burst ops implementation function of hns3 PMD driver,
> there is one check whether there are enough BDs in the TX queue.

Out of curiosity, is BD refers to "buffer descriptor"? What is the difference
between Tx descriptor and TX BD?

> If not, driver will stop sending the packets.
> 
> Currently in the 'for' process loop, the next_to_use member of
> TX queue is not updated in time after processing BDs of one packet,
> which results in the invalid action of checking whether there are
> enough BDs and failure in sending packets.
> 
> This patch fixes it by moving the assignment statment of the
> next_to_use member of TX queue to the place after porcessing TX BDs
> in the 'for' loop.
> 
> Fixes: bba636698316 ("net/hns3: support Rx/Tx and related operations")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Hongbo Zheng <zhenghongbo3@huawei.com>
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
> ---
>  drivers/net/hns3/hns3_rxtx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/hns3/hns3_rxtx.c b/drivers/net/hns3/hns3_rxtx.c
> index 34cb7faf9..816644713 100644
> --- a/drivers/net/hns3/hns3_rxtx.c
> +++ b/drivers/net/hns3/hns3_rxtx.c
> @@ -1649,6 +1649,7 @@ hns3_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  		} while (m_seg != NULL);
>  
>  		nb_hold += i;
> +		txq->next_to_use = tx_next_use;
>  	}
>  
>  end_of_tx:
> @@ -1656,7 +1657,6 @@ hns3_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  	if (likely(nb_tx)) {
>  		hns3_queue_xmit(txq, nb_hold);
>  		txq->next_to_clean = tx_next_clean;
> -		txq->next_to_use   = tx_next_use;
>  		txq->tx_bd_ready   = tx_bd_ready - nb_hold;
>  	}
>  
>