Writing zero-length descriptors to the hardware can cause the hardware
to reject that packet and stop transmitting altogether.

Fixes: 4022f9999f56 ("net/gve: support basic Tx data path for DQO")
Cc: junfeng....@intel.com
Cc: sta...@dpdk.org

Signed-off-by: Joshua Washington <joshw...@google.com>
Reviewed-by: Ankit Garg <nkt...@google.com>
---
 drivers/net/gve/gve_tx_dqo.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/gve/gve_tx_dqo.c b/drivers/net/gve/gve_tx_dqo.c
index 652a0e5175..b2e5aae634 100644
--- a/drivers/net/gve/gve_tx_dqo.c
+++ b/drivers/net/gve/gve_tx_dqo.c
@@ -168,6 +168,11 @@ gve_tx_burst_dqo(void *tx_queue, struct rte_mbuf 
**tx_pkts, uint16_t nb_pkts)
                        if (sw_ring[sw_id] != NULL)
                                PMD_DRV_LOG(DEBUG, "Overwriting an entry in 
sw_ring");
 
+                       /* Skip writing descriptor if mbuf has no data. */
+                       if (!tx_pkt->data_len)
+                               goto finish_mbuf;
+
+                       txd = &txr[tx_id];
                        sw_ring[sw_id] = tx_pkt;
 
                        /* fill Tx descriptors */
@@ -189,12 +194,14 @@ gve_tx_burst_dqo(void *tx_queue, struct rte_mbuf 
**tx_pkts, uint16_t nb_pkts)
                                tx_id = (tx_id + 1) & mask;
                        }
 
+finish_mbuf:
                        sw_id = (sw_id + 1) & sw_mask;
                        bytes += tx_pkt->data_len;
                        tx_pkt = tx_pkt->next;
                } while (tx_pkt);
 
-               /* fill the last descriptor with End of Packet (EOP) bit */
+               /* fill the last written descriptor with End of Packet (EOP) 
bit */
+               txd = &txr[(tx_id - 1) & mask];
                txd->pkt.end_of_packet = 1;
 
                txq->nb_free -= nb_descs;
-- 
2.50.0.727.gbf7dc18ff4-goog

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