From 982c9eabe68c6d5a0e8328df8dc11c5f315eddf0 Mon Sep 17 00:00:00 2001
From: Chengwen Feng <[email protected]>
Date: Fri, 21 Oct 2022 15:36:14 +0800
Subject: [PATCH 138/189] net/hns3: fix next-to-use overflow in simple Tx

If txq's next-to-use plus nb_pkts equal txq's nb_tx_desc when using
simple xmit algorithm, the txq's next-to-use will equal nb_tx_desc
fter the xmit, this does not cause Tx exceptions, but may affect other
ops that depend on this field, such as tx_descriptor_status.

Fixes: 7ef933908f04 ("net/hns3: add simple Tx path")
Cc: [email protected]

Signed-off-by: Chengwen Feng <[email protected]>
Signed-off-by: Dongdong Liu <[email protected]>
---
 drivers/net/hns3/hns3_rxtx.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hns3/hns3_rxtx.c b/drivers/net/hns3/hns3_rxtx.c
index 840ca384ce..93cc70477d 100644
--- a/drivers/net/hns3/hns3_rxtx.c
+++ b/drivers/net/hns3/hns3_rxtx.c
@@ -4129,14 +4129,16 @@ hns3_xmit_pkts_simple(void *tx_queue,
 	}
 
 	txq->tx_bd_ready -= nb_pkts;
-	if (txq->next_to_use + nb_pkts > txq->nb_tx_desc) {
+	if (txq->next_to_use + nb_pkts >= txq->nb_tx_desc) {
 		nb_tx = txq->nb_tx_desc - txq->next_to_use;
 		hns3_tx_fill_hw_ring(txq, tx_pkts, nb_tx);
 		txq->next_to_use = 0;
 	}
 
-	hns3_tx_fill_hw_ring(txq, tx_pkts + nb_tx, nb_pkts - nb_tx);
-	txq->next_to_use += nb_pkts - nb_tx;
+	if (nb_pkts > nb_tx) {
+		hns3_tx_fill_hw_ring(txq, tx_pkts + nb_tx, nb_pkts - nb_tx);
+		txq->next_to_use += nb_pkts - nb_tx;
+	}
 
 	hns3_write_txq_tail_reg(txq, nb_pkts);
 
-- 
2.23.0