nfp: flower: add rcu locks when accessing netdev for tunnels

Add rcu locks when accessing netdev when processing route request
and tunnel keep alive messages received from hardware.

Fixes: 8e6a9046 ("nfp: flower vxlan neighbour offload")
Fixes: 856f5b13 ("nfp: flower vxlan neighbour keep-alive")
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c

@@ -168,6 +168,7 @@ void nfp_tunnel_keep_alive(struct nfp_app *app, struct sk_buff *skb)
 		return;
 	}
 
+	rcu_read_lock();
 	for (i = 0; i < count; i++) {
 		ipv4_addr = payload->tun_info[i].ipv4;
 		port = be32_to_cpu(payload->tun_info[i].egress_port);
@@ -183,6 +184,7 @@ void nfp_tunnel_keep_alive(struct nfp_app *app, struct sk_buff *skb)
 		neigh_event_send(n, NULL);
 		neigh_release(n);
 	}
+	rcu_read_unlock();
 }
 
 static int
@@ -367,9 +369,10 @@ void nfp_tunnel_request_route(struct nfp_app *app, struct sk_buff *skb)
 
 	payload = nfp_flower_cmsg_get_data(skb);
 
+	rcu_read_lock();
 	netdev = nfp_app_dev_get(app, be32_to_cpu(payload->ingress_port), NULL);
 	if (!netdev)
-		goto route_fail_warning;
+		goto fail_rcu_unlock;
 
 	flow.daddr = payload->ipv4_addr;
 	flow.flowi4_proto = IPPROTO_UDP;
@@ -379,21 +382,23 @@ void nfp_tunnel_request_route(struct nfp_app *app, struct sk_buff *skb)
 	rt = ip_route_output_key(dev_net(netdev), &flow);
 	err = PTR_ERR_OR_ZERO(rt);
 	if (err)
-		goto route_fail_warning;
+		goto fail_rcu_unlock;
 #else
-	goto route_fail_warning;
+	goto fail_rcu_unlock;
 #endif
 
 	/* Get the neighbour entry for the lookup */
 	n = dst_neigh_lookup(&rt->dst, &flow.daddr);
 	ip_rt_put(rt);
 	if (!n)
-		goto route_fail_warning;
-	nfp_tun_write_neigh(n->dev, app, &flow, n, GFP_KERNEL);
+		goto fail_rcu_unlock;
+	nfp_tun_write_neigh(n->dev, app, &flow, n, GFP_ATOMIC);
 	neigh_release(n);
+	rcu_read_unlock();
 	return;
 
-route_fail_warning:
+fail_rcu_unlock:
+	rcu_read_unlock();
 	nfp_flower_cmsg_warn(app, "Requested route not found.\n");
 }