netdev - Re: [PATCH] selftests: txtimestamp: tear down setup() 'tc' and 'ip' env on EXIT

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Date:   Tue, 21 Jul 2020 11:04:06 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Paolo Pisati <paolo.pisati@...onical.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Shuah Khan <shuah@...nel.org>, Jian Yang <jianyang@...gle.com>,
        Network Development <netdev@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] selftests: txtimestamp: tear down setup() 'tc' and 'ip'
 env on EXIT

On Tue, Jul 21, 2020 at 10:52 AM Paolo Pisati
<paolo.pisati@...onical.com> wrote:
>
> Add a cleanup() path upon exit, making it possible to run the test twice in a
> row:
>
> $ sudo bash -x ./txtimestamp.sh
> + set -e
> ++ ip netns identify
> + [[ '' == \r\o\o\t ]]
> + main
> + [[ 0 -eq 0 ]]
> + run_test_all
> + setup
> + tc qdisc add dev lo root netem delay 1ms
> Error: Exclusivity flag on, cannot modify.
>
> Signed-off-by: Paolo Pisati <paolo.pisati@...onical.com>

The test should already clean up after itself, by being run inside a
network namespace. That is a more robust method to ensure that all
state is reset.

The issue here is that the else branch is taken in

  if [[ "$(ip netns identify)" == "root" ]]; then
          ./in_netns.sh $0 $@
  else
          main $@
  fi

because the ip netns identify usually returns an empty string, not
"root". If we fix that, no need to add additional cleanup.