From: Peng Li <lipeng321@huawei.com>
Date: Thu, 20 Dec 2018 11:52:05 +0800
Subject: net: hns3: fix the descriptor index when get rss type
Patch-mainline: v5.0-rc1
Git-commit: 31a16f99e02c2e0b40a5fb05d66f5e56721027e2
References: bsc#1104353 FATE#326415

Driver gets rss information from the last descriptor of the packet.
When driver handle the rss type, ring->next_to_clean indicates the
first descriptor of next packet.

This patch fix the descriptor index with "ring->next_to_clean - 1".

Fixes: 232fc64b6e62 ("net: hns3: Add HW RSS hash information to RX skb")
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -2332,9 +2332,16 @@ static bool hns3_parse_vlan_tag(struct h
 static void hns3_set_rx_skb_rss_type(struct hns3_enet_ring *ring,
 				     struct sk_buff *skb)
 {
-	struct hns3_desc *desc = &ring->desc[ring->next_to_clean];
 	struct hnae3_handle *handle = ring->tqp->handle;
 	enum pkt_hash_types rss_type;
+	struct hns3_desc *desc;
+	int last_bd;
+
+	/* When driver handle the rss type, ring->next_to_clean indicates the
+	 * first descriptor of next packet, need -1 here.
+	 */
+	last_bd = (ring->next_to_clean - 1 + ring->desc_num) % ring->desc_num;
+	desc = &ring->desc[last_bd];
 
 	if (le32_to_cpu(desc->rx.rss_hash))
 		rss_type = handle->kinfo.rss_type;