[dpdk-stable] [PATCH] net/mlx5: fix transmit descriptor with VLAN insertions

[Viacheslav Ovsiienko <viacheslavo@mellanox.com>]

If VLAN tag insertion transmit offload is engaged
(DEV_TX_OFFLOAD_VLAN_INSERT in tx queue configuration is set)
the transmit descriptor may be built with wrong format, due to
packet length is not adjusted. Also, the ring buffer wrapup
is not handled correctly.

Fixes: 18a1c20044c0 ("net/mlx5: implement Tx burst template")
Cc: stable@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
---
 drivers/net/mlx5/mlx5_rxtx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 8ec90c3..f540977 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -2861,13 +2861,14 @@ enum mlx5_txcmp_code {
 	memcpy(pdst, buf, MLX5_DSEG_MIN_INLINE_SIZE);
 	buf += MLX5_DSEG_MIN_INLINE_SIZE;
 	pdst += MLX5_DSEG_MIN_INLINE_SIZE;
+	len -= MLX5_DSEG_MIN_INLINE_SIZE;
 	/* Insert VLAN ethertype + VLAN tag. Pointer is aligned. */
 	assert(pdst == RTE_PTR_ALIGN(pdst, MLX5_WSEG_SIZE));
+	if (unlikely(pdst >= (uint8_t *)txq->wqes_end))
+		pdst = (uint8_t *)txq->wqes;
 	*(uint32_t *)pdst = rte_cpu_to_be_32((RTE_ETHER_TYPE_VLAN << 16) |
 					      loc->mbuf->vlan_tci);
 	pdst += sizeof(struct rte_vlan_hdr);
-	if (unlikely(pdst >= (uint8_t *)txq->wqes_end))
-		pdst = (uint8_t *)txq->wqes;
 	/*
 	 * The WQEBB space availability is checked by caller.
 	 * Here we should be aware of WQE ring buffer wraparound only.
-- 
1.8.3.1