From 6fa9d691b91ac6e6d8a1e3799d24324a6a70663f Mon Sep 17 00:00:00 2001
From: Jose Abreu <Jose.Abreu@synopsys.com>
Date: Tue, 10 Sep 2019 16:41:22 +0200
Subject: [PATCH] net: stmmac: Prevent divide-by-zero

When RX Coalesce settings are set to all zero (which is a valid setting)
we will currently get a divide-by-zero error. Fix it.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 686b820681422..6e44013b20ccb 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3418,7 +3418,9 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
 		stmmac_refill_desc3(priv, rx_q, p);
 
 		rx_q->rx_count_frames++;
-		rx_q->rx_count_frames %= priv->rx_coal_frames;
+		rx_q->rx_count_frames += priv->rx_coal_frames;
+		if (rx_q->rx_count_frames > priv->rx_coal_frames)
+			rx_q->rx_count_frames = 0;
 		use_rx_wd = priv->use_riwt && rx_q->rx_count_frames;
 
 		dma_wmb();
-- 
2.30.2