From 1855ad5360a18131e5c4b4afa1a1c5dea6e456c6 Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Mon, 6 Apr 2020 23:56:30 +0200
Subject: [PATCH] mt76: mt7615: fix possible division by 0 in mt7615_mac_update_mib_stats
Git-commit: 1855ad5360a18131e5c4b4afa1a1c5dea6e456c6
Patch-mainline: v5.8-rc1
References: jsc#SLE-13430

Check that val is not zero before aggr_per estimation in order to avoid a
possible division by 0

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/mediatek/mt76/mt7615/mac.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mac.c b/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
index ed6eb19f48c5..1ef988883660 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
@@ -1773,9 +1773,11 @@ mt7615_mac_update_mib_stats(struct mt7615_phy *phy)
 
 	val = mt76_get_field(dev, MT_MIB_SDR14(ext_phy),
 			     MT_MIB_AMPDU_MPDU_COUNT);
-	val2 = mt76_get_field(dev, MT_MIB_SDR15(ext_phy),
-			      MT_MIB_AMPDU_ACK_COUNT);
-	mib->aggr_per = 1000 * (val - val2) / val;
+	if (val) {
+		val2 = mt76_get_field(dev, MT_MIB_SDR15(ext_phy),
+				      MT_MIB_AMPDU_ACK_COUNT);
+		mib->aggr_per = 1000 * (val - val2) / val;
+	}
 
 	aggr = ext_phy ? ARRAY_SIZE(dev->mt76.aggr_stats) / 2 : 0;
 	for (i = 0; i < 4; i++) {
-- 
2.16.4