[PATCH net-next] virtio-net: per-queue RPS config

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

From: Willem de Bruijn <willemb@google.com>

On multiqueue network devices, RPS maps are configured independently
for each receive queue through /sys/class/net/$DEV/queues/rx-*.

On virtio-net currently all packets use the map from rx-0, because the
real rx queue is not known at time of map lookup by get_rps_cpu.

Call skb_record_rx_queue in the driver rx path to make lookup work.

Recording the receive queue has ramifications beyond RPS, such as in
sticky load balancing decisions for sockets (skb_tx_hash) and XPS.

Reported-by: Mark Hlady <mhlady@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 drivers/net/virtio_net.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0237250860467..236ba5d5fb4bb 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1035,6 +1035,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 		goto frame_err;
 	}
 
+	skb_record_rx_queue(skb, vq2rxq(rq->vq));
 	skb->protocol = eth_type_trans(skb, dev);
 	pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
 		 ntohs(skb->protocol), skb->len, skb->pkt_type);
-- 
2.20.1.321.g9e740568ce-goog