r8169: fix vlan tag read ordering.

Control of receive descriptor must not be returned to ethernet chipset
before vlan tag processing is done.

VLAN tag receive word is now reset both in normal and error path.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Spotted-by: Timo Teras <timo.teras@iki.fi>
Cc: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -1826,8 +1826,6 @@ static void rtl8169_rx_vlan_tag(struct RxDesc *desc, struct sk_buff *skb)
 
 	if (opts2 & RxVlanTag)
 		__vlan_hwaccel_put_tag(skb, swab16(opts2 & 0xffff));
-
-	desc->opts2 = 0;
 }
 
 static int rtl8169_gset_tbi(struct net_device *dev, struct ethtool_cmd *cmd)
@@ -6064,8 +6062,6 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget
 			    !(status & (RxRWT | RxFOVF)) &&
 			    (dev->features & NETIF_F_RXALL))
 				goto process_pkt;
-
-			rtl8169_mark_to_asic(desc, rx_buf_sz);
 		} else {
 			struct sk_buff *skb;
 			dma_addr_t addr;
@@ -6086,16 +6082,14 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget
 			if (unlikely(rtl8169_fragmented_frame(status))) {
 				dev->stats.rx_dropped++;
 				dev->stats.rx_length_errors++;
-				rtl8169_mark_to_asic(desc, rx_buf_sz);
-				continue;
+				goto release_descriptor;
 			}
 
 			skb = rtl8169_try_rx_copy(tp->Rx_databuff[entry],
 						  tp, pkt_size, addr);
-			rtl8169_mark_to_asic(desc, rx_buf_sz);
 			if (!skb) {
 				dev->stats.rx_dropped++;
-				continue;
+				goto release_descriptor;
 			}
 
 			rtl8169_rx_csum(skb, status);
@@ -6111,6 +6105,10 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget
 			tp->rx_stats.bytes += pkt_size;
 			u64_stats_update_end(&tp->rx_stats.syncp);
 		}
+release_descriptor:
+		desc->opts2 = 0;
+		wmb();
+		rtl8169_mark_to_asic(desc, rx_buf_sz);
 	}
 
 	count = cur_rx - tp->cur_rx;