RE: [PATCH v3 2/2] net/ice: fix scalar Tx path segment

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Ye, MingjinX <mingjinx.ye@intel.com>
> Sent: Friday, November 11, 2022 8:04 PM
> To: dev@dpdk.org
> Cc: Yang, Qiming <qiming.yang@intel.com>; stable@dpdk.org; Zhou, YidingX
> <yidingx.zhou@intel.com>; Ye, MingjinX <mingjinx.ye@intel.com>; Zhang, Qi
> Z <qi.z.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Lu,
> Wenzhuo <wenzhuo.lu@intel.com>; Ferruh Yigit <ferruh.yigit@intel.com>; Li,
> Xiaoyun <xiaoyun.li@intel.com>; Liu, KevinX <kevinx.liu@intel.com>
> Subject: [PATCH v3 2/2] net/ice: fix scalar Tx path segment
> 
> The scalar Tx path would send empty buffer that causes the Tx queue to
> overflow.
> 
> This patch adds the last buffer length judgment in tx_prepare to fix this issue,
> rte_errno will be set to EINVAL and returned if the last buffer is empty.
> 
> Fixes: 17c7d0f9d6a4 ("net/ice: support basic Rx/Tx")
> Fixes: ccf33dccf7aa ("net/ice: check illegal packet sizes")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> ---
>  drivers/net/ice/ice_rxtx.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/net/ice/ice_rxtx.c b/drivers/net/ice/ice_rxtx.c index
> e6ddd2513d..69358f6a3a 100644
> --- a/drivers/net/ice/ice_rxtx.c
> +++ b/drivers/net/ice/ice_rxtx.c
> @@ -3643,6 +3643,22 @@ ice_set_tx_function_flag(struct rte_eth_dev *dev,
> struct ice_tx_queue *txq)
>  #define ICE_MIN_TSO_MSS            64
>  #define ICE_MAX_TSO_MSS            9728
>  #define ICE_MAX_TSO_FRAME_SIZE     262144
> +
> +/*Check for invalid mbuf*/
> +static inline uint16_t
> +ice_check_mbuf(struct rte_mbuf *tx_pkt) {

Better to name the function to exactly match what it does. 
e.g.: ice_check_emtpy_mbuf
and also declare it as inline.

> +	struct rte_mbuf *txd = tx_pkt;
> +
> +	while (txd != NULL) {
> +		if (txd->data_len == 0)
> +			return -1;
> +		txd = txd->next;
> +	}
> +
> +	return 0;
> +}
> +
>  uint16_t
>  ice_prep_pkts(__rte_unused void *tx_queue, struct rte_mbuf **tx_pkts,
>  	      uint16_t nb_pkts)
> @@ -3653,6 +3669,7 @@ ice_prep_pkts(__rte_unused void *tx_queue,
> struct rte_mbuf **tx_pkts,
>  	struct ice_tx_queue *txq = tx_queue;
>  	struct rte_eth_dev *dev = &rte_eth_devices[txq->port_id];
>  	uint16_t max_frame_size = dev->data->mtu + ICE_ETH_OVERHEAD;
> +	uint16_t nb_used;
> 
>  	for (i = 0; i < nb_pkts; i++) {
>  		m = tx_pkts[i];
> @@ -3689,6 +3706,13 @@ ice_prep_pkts(__rte_unused void *tx_queue,
> struct rte_mbuf **tx_pkts,
>  			rte_errno = -ret;
>  			return i;
>  		}
> +
> +		if (!(ol_flags & RTE_MBUF_F_TX_TCP_SEG) &&
> +			ice_check_mbuf(m)) {

Why "!(ol_flags & RTE_MBUF_F_TX_TCP_SEG)" is needed here?
A empty mbuf with TSO enabled is still acceptable?

> +			rte_errno = EINVAL;
> +			PMD_DRV_LOG(ERR, "INVALID mbuf:	last mbuf
> data_len=[0]");
> +			return i;
> +		}
>  	}
>  	return i;
>  }
> --
> 2.34.1