[PATCH net] selftests: net: big_tcp_tunnels: Fix the IPv6 route change

[Haishuang Yan]

On slow machines, do_test() raises initcwnd on the route into the tunnel
with "ip route change". For IPv6 traffic this fails with:

  RTNETLINK answers: No such file or directory

The IPv6 prefix route of the tunnel address has metric 256, while
"ip -6 route change" without a metric looks for a route with the default
metric 1024, so nothing is changed. The test still passes, but without
the larger initcwnd it is meant to use.

Pass the metric of the prefix route.

Fixes: 1d62b83fb751 ("selftests: net: Fix slow configurations in big_tcp_tunnels.sh")
Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
---
 tools/testing/selftests/net/big_tcp_tunnels.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/big_tcp_tunnels.sh b/tools/testing/selftests/net/big_tcp_tunnels.sh
index cc0875e52fb9..fb43fed824e3 100755
--- a/tools/testing/selftests/net/big_tcp_tunnels.sh
+++ b/tools/testing/selftests/net/big_tcp_tunnels.sh
@@ -145,7 +145,8 @@ do_test() {
 			    route change 192.168.2.0/24 dev tun0 initcwnd 100
 		else
 			ip -netns "$CLIENT_NS" -6 \
-			    route change 2001:db8::2:0/112 dev tun0 initcwnd 100
+			    route change 2001:db8::2:0/112 dev tun0 initcwnd 100 \
+			    metric 256
 		fi
 	else
 		ip netns exec "$CLIENT_NS" \
-- 
2.43.0