netdev - Re: [PATCH net-next] selftests: net: Test headroom handling of ip6

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Date:   Thu, 24 May 2018 09:19:53 -0700
From:   William Tu <u9012063@...il.com>
To:     Petr Machata <petrm@...lanox.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        linux-kselftest@...r.kernel.org,
        David Miller <davem@...emloft.net>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH net-next] selftests: net: Test headroom handling of
 ip6_gre devices

Hi Petr,

I tried to test this patch on latest net-next but encounter a couple issues.

On Wed, May 23, 2018 at 9:41 AM, Petr Machata <petrm@...lanox.com> wrote:
> Commit 5691484df961 ("net: ip6_gre: Fix headroom request in
> ip6erspan_tunnel_xmit()") and commit 01b8d064d58b ("net: ip6_gre:
> Request headroom in __gre6_xmit()") fix problems in reserving headroom
> in the packets tunneled through ip6gre/tap and ip6erspan netdevices.
>
> These two patches included snippets that reproduced the issues. This
> patch elevates the snippets to a full-fledged test case.
>
> Suggested-by: David Miller <davem@...emloft.net>
> Signed-off-by: Petr Machata <petrm@...lanox.com>
> ---
>  tools/testing/selftests/net/ip6_gre_headroom.sh | 59 +++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
>  create mode 100755 tools/testing/selftests/net/ip6_gre_headroom.sh
>
> diff --git a/tools/testing/selftests/net/ip6_gre_headroom.sh b/tools/testing/selftests/net/ip6_gre_headroom.sh
> new file mode 100755
> index 0000000..9aaf63fd
> --- /dev/null
> +++ b/tools/testing/selftests/net/ip6_gre_headroom.sh
> @@ -0,0 +1,59 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Test that enough headroom is reserved for the first packet passing through an
> +# IPv6 GRE-like netdevice.
> +
> +setup_prepare()
> +{
> +       ip link add h1 type veth peer name swp1
> +       ip link add h3 type veth peer name swp3
> +
> +       ip link set dev h1 up
> +       ip address add 192.0.2.1/28 dev h1
> +
> +       ip link add dev vh3 type vrf table 20
> +       ip link set dev h3 master vh3
> +       ip link set dev vh3 up
> +       ip link set dev h3 up
> +
> +       ip link set dev swp3 up
> +       ip address add dev swp3 2001:db8:2::1/64
> +
> +       ip link set dev swp1 up
> +       tc qdisc add dev swp1 clsact
> +}
> +
> +cleanup()
> +{
> +       ip link del dev swp1
> +       ip link del dev swp3
> +       ip link del dev vh3
I think we also need to do:
ip link del dev gt6

> +}
> +
> +test_headroom()
> +{
> +       ip link add name gt6 "$@"
> +       ip link set dev gt6 up
> +
> +       sleep 1
> +
> +       tc filter add dev swp1 ingress pref 1000 matchall skip_hw \
> +               action mirred egress mirror dev gt6
> +       ping -I h1 192.0.2.2 -c 1 -w 2 &> /dev/null

I increase ping count from 1 to 1000
and after a while the program hangs when I try to ctrl+c
+ cleanup
+ ip link del dev swp1
dmesg shows:
....
[ 1256.002453] unregister_netdevice: waiting for swp1 to become free.
Usage count = 9
[ 1266.082571] unregister_netdevice: waiting for swp1 to become free.
Usage count = 9
[ 1276.163011] unregister_netdevice: waiting for swp1 to become free.
Usage count = 9

Thanks
William