Subject: Re: [PATCH net] selftests: forwarding: vxlan_bridge_1d: fix tos value

From: Petr Machata <[email-masked]>
Date: Thu, 13 Feb 2020 13:52:49 +0100

Hangbin Liu <[email-masked]> writes:

> After commit 71130f29979c ("vxlan: fix tos value before xmit") we start
> strict vxlan xmit tos value by RT_TOS(), which limits the tos value less

I don't understand how it is OK to slice the TOS field like this. It
could contain a DSCP value, which will be mangled.

> than 0x1E. With current value 0x40 the test will failed with "v1: Expected
> to capture 10 packets, got 0". So let's choose a smaller tos value for
> testing.
>
> Fixes: d417ecf533fe ("selftests: forwarding: vxlan_bridge_1d: Add a TOS test")
> Signed-off-by: Hangbin Liu <[email-masked]>
> ---
>  tools/testing/selftests/net/forwarding/vxlan_bridge_1d.sh | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/net/forwarding/vxlan_bridge_1d.sh b/tools/testing/selftests/net/forwarding/vxlan_bridge_1d.sh
> index bb10e33690b2..353613fc1947 100755
> --- a/tools/testing/selftests/net/forwarding/vxlan_bridge_1d.sh
> +++ b/tools/testing/selftests/net/forwarding/vxlan_bridge_1d.sh
> @@ -516,9 +516,9 @@ test_tos()
>  	RET=0
>
>  	tc filter add dev v1 egress pref 77 prot ip \
> -		flower ip_tos 0x40 action pass
> -	vxlan_ping_test $h1 192.0.2.3 "-Q 0x40" v1 egress 77 10
> -	vxlan_ping_test $h1 192.0.2.3 "-Q 0x30" v1 egress 77 0
> +		flower ip_tos 0x11 action pass
> +	vxlan_ping_test $h1 192.0.2.3 "-Q 0x11" v1 egress 77 10
> +	vxlan_ping_test $h1 192.0.2.3 "-Q 0x12" v1 egress 77 0

0x11 and 0x12 set the ECN bits, I think it would be better to avoid
that. It works just as well with 0x14 and 0x18.

>  	tc filter del dev v1 egress pref 77 prot ip
>
>  	log_test "VXLAN: envelope TOS inheritance"