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

["Alice Mikityanska" <alice.kernel@fastmail.im>]

On Wed, Oct 7, 2026, at 04:47, Haishuang Yan wrote:
> 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

Thanks for the fix! It's already merged, but anyway:

Tested-by: Alice Mikityanska <alice.kernel@fastmail.im>

> 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@cmss.chinamobile.com>
> ---
>  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