[PATCH 1/2] net/mlx5: fix num seg assumption on vPMD

[Shahaf Shuler <shahafs@mellanox.com>]

vPMD Tx function assumes that after the scatter of the
multi-segment packets the next packet will be a single segment packet.

This is not current as the function can return due to lack of resources
without sending all of the multi-segment mbufs sequence.

Fixes: 6cb559d67b83 ("net/mlx5: add vectorized Rx/Tx burst for x86")
Cc: stable@dpdk.org

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
---

This patch should be applied only after the series:
http://dpdk.org/dev/patchwork/patch/27367/

---
 drivers/net/mlx5/mlx5_rxtx_vec_sse.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_sse.c b/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
index 8560f745a..30727e6dd 100644
--- a/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
+++ b/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
@@ -119,8 +119,7 @@ txq_wr_dseg_v(struct txq *txq, __m128i *dseg,
 }
 
 /**
- * Count the number of continuous single segment packets. The first packet must
- * be a single segment packet.
+ * Count the number of continuous single segment packets.
  *
  * @param pkts
  *   Pointer to array of packets.
@@ -137,7 +136,8 @@ txq_check_multiseg(struct rte_mbuf **pkts, uint16_t pkts_n)
 
 	if (!pkts_n)
 		return 0;
-	assert(NB_SEGS(pkts[0]) == 1);
+	if (NB_SEGS(pkts[0]) > 1)
+		return 0;
 	/* Count the number of continuous single segment packets. */
 	for (pos = 1; pos < pkts_n; ++pos)
 		if (NB_SEGS(pkts[pos]) > 1)
@@ -502,6 +502,8 @@ mlx5_tx_burst_vec(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		n = RTE_MIN((uint16_t)(pkts_n - nb_tx), MLX5_VPMD_TX_MAX_BURST);
 		if (!(txq->flags & ETH_TXQ_FLAGS_NOMULTSEGS))
 			n = txq_check_multiseg(&pkts[nb_tx], n);
+			if (!n)
+				break;
 		if (!(txq->flags & ETH_TXQ_FLAGS_NOOFFLOADS))
 			n = txq_calc_offload(txq, &pkts[nb_tx], n, &cs_flags);
 		ret = txq_burst_v(txq, &pkts[nb_tx], n, cs_flags);
-- 
2.12.0