From 83fa6ac68a19f16788d4d43c5d3f36021dea9e23 Mon Sep 17 00:00:00 2001
From: "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Date: Thu, 4 Jul 2019 19:10:27 +0000
Subject: [PATCH] [NOT-UPSTREAM] virtio-net: Add droppkt param to force drop
 packets for 20s

---
 drivers/net/virtio_net.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index c70441f45..f14f67b94 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -36,10 +36,14 @@ static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
 
 static bool csum = true, gso = true, napi_tx;
+static int droppkt=0, droppingpkt=1;
+
 module_param(csum, bool, 0444);
 module_param(gso, bool, 0444);
 module_param(napi_tx, bool, 0644);
 
+module_param(droppkt, int, 0644);
+
 /* FIXME: MTU in config. */
 #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
 #define GOOD_COPY_LEN	128
@@ -1340,11 +1344,25 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 	/* timestamp packet in software */
 	skb_tx_timestamp(skb);
 
+	if (unlikely(droppkt)) {
+		pr_err_once("dropping pkts\n");
+		if (droppingpkt == 1)
+			droppingpkt = jiffies;
+		else {
+			if (jiffies_to_msecs(jiffies - droppingpkt) > 20000) { /* 20s */
+				droppingpkt = 1;
+				droppkt = 0;
+			}
+		}
+		goto fakedrop;
+	}
+
 	/* Try to transmit */
 	err = xmit_skb(sq, skb);
 
 	/* This should not happen! */
 	if (unlikely(err)) {
+fakedrop:
 		dev->stats.tx_fifo_errors++;
 		if (net_ratelimit())
 			dev_warn(&dev->dev,
-- 
2.17.1