[PATCH v2] net/iavf: fix checksum offloading

[David Marchand <david.marchand@redhat.com>]

l2_len and l3_len fields are related to Tx offloading features.

It is undefined in the DPDK API what those fields may contain if an
application did not request a Tx offload.

Skip reading them if no Tx offloads has been requested.

Fixes: 1e728b01120c ("net/iavf: rework Tx path")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
Changes since v1:
- updated commitlog and patch to focus on undefined behavior of net/iavf
  wrt reading l2_len/l3_len,

---
 drivers/net/iavf/iavf_rxtx.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/iavf/iavf_rxtx.c b/drivers/net/iavf/iavf_rxtx.c
index f7df4665d1..33b0f9f482 100644
--- a/drivers/net/iavf/iavf_rxtx.c
+++ b/drivers/net/iavf/iavf_rxtx.c
@@ -2643,6 +2643,9 @@ iavf_build_data_desc_cmd_offset_fields(volatile uint64_t *qw1,
 		l2tag1 |= m->vlan_tci;
 	}
 
+	if ((m->ol_flags & IAVF_TX_CKSUM_OFFLOAD_MASK) == 0)
+		goto skip_cksum;
+
 	/* Set MACLEN */
 	if (m->ol_flags & RTE_MBUF_F_TX_TUNNEL_MASK &&
 			!(m->ol_flags & RTE_MBUF_F_TX_SEC_OFFLOAD))
@@ -2702,6 +2705,7 @@ iavf_build_data_desc_cmd_offset_fields(volatile uint64_t *qw1,
 		break;
 	}
 
+skip_cksum:
 	*qw1 = rte_cpu_to_le_64((((uint64_t)command <<
 		IAVF_TXD_DATA_QW1_CMD_SHIFT) & IAVF_TXD_DATA_QW1_CMD_MASK) |
 		(((uint64_t)offset << IAVF_TXD_DATA_QW1_OFFSET_SHIFT) &
-- 
2.41.0