[PATCH v4 2/2] net/ice: fix scalar Tx path segment

[Mingjin Ye <mingjinx.ye@intel.com>]

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>

v3:
	* delete unused variable.
	* Full detection of mbufs.
---
 drivers/net/ice/ice_rxtx.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/net/ice/ice_rxtx.c b/drivers/net/ice/ice_rxtx.c
index e6ddd2513d..9017353943 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 empty mbuf*/
+static inline uint16_t
+ice_check_empty_mbuf(struct rte_mbuf *tx_pkt)
+{
+	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)
@@ -3689,6 +3705,12 @@ ice_prep_pkts(__rte_unused void *tx_queue, struct rte_mbuf **tx_pkts,
 			rte_errno = -ret;
 			return i;
 		}
+
+		if (ice_check_empty_mbuf(m) != 0) {
+			rte_errno = EINVAL;
+			PMD_DRV_LOG(ERR, "INVALID mbuf:	last mbuf data_len=[0]");
+			return i;
+		}
 	}
 	return i;
 }
-- 
2.34.1