Disable the network device & turn off carrier before modifying the
number of queue pairs.
Process all the in-flight packets and then turn on carrier, followed
by waking up all the queues on the network device.

Signed-off-by: Abhinav Jain <redacted>
---
 drivers/net/virtio_net.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 61a57d134544..d0a655a3b4c6 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -3447,7 +3447,6 @@ static void virtnet_get_drvinfo(struct net_device *dev,

 }

-/* TODO: Eliminate OOO packets during switching */
 static int virtnet_set_channels(struct net_device *dev,
                                struct ethtool_channels *channels)
 {

@@ -3471,6 +3470,15 @@ static int virtnet_set_channels(struct net_device *dev,
        if (vi->rq[0].xdp_prog)
                return -EINVAL;

+       /* Disable network device to prevent packet processing during
+        * the switch.
+        */
+       netif_tx_disable(dev);
+       netif_carrier_off(dev);

+
+       /* Make certain that all in-flight packets are processed. */
+       synchronize_net();
+
        cpus_read_lock();
        err = virtnet_set_queues(vi, queue_pairs);
        if (err) {

@@ -3482,7 +3490,12 @@ static int virtnet_set_channels(struct net_device *dev,

        netif_set_real_num_tx_queues(dev, queue_pairs);
        netif_set_real_num_rx_queues(dev, queue_pairs);
- err:
+
+       /* Restart the network device */
+       netif_carrier_on(dev);
+       netif_tx_wake_all_queues(dev);
+
+err:
        return err;
 }

--

2.34.1