Re: [ovs-dev] selftests: openvswitch: Questions about possible enhancements

On Wed, Apr 24, 2024 at 05:44:05PM +0100, Simon Horman wrote:

Hi Aaron, Jakub, all,

I have recently been exercising the Open vSwitch kernel selftests, using vng, something like this:

TESTDIR="tools/testing/selftests/net/openvswitch"

    vng -v --run . --user root --cpus 2 \
            --overlay-rwdir "$PWD" -- \
            "modprobe openvswitch && \
 echo \"timeout=90\" >> \"${TESTDIR}/settings\" && \
             make -C \"$TESTDIR\" run_tests"

And I have some observations that I'd like to ask about.

1. Building the kernel using the following command does not build the openvswitch kernel module.

   vng -v --build \ --config tools/testing/selftests/net/config

   All that seems to be missing is CONFIG_OPENVSWITCH=m and I am wondering what the best way of resolving this is.

   Perhaps I am doing something wrong. Or perhaps tools/testing/selftests/net/openvswitch/config should be created? If so, should it include (most of?) what is in tools/testing/selftests/net/config, or just CONFIG_OPENVSWITCH=m?

2. As per my example above, it seems that a modprobe openvswitch is required (if openvswitch is a module).

   Again, perhaps I am doing something wrong. But if not, should this be incorporated into tools/testing/selftests/net/openvswitch/openvswitch.sh or otherwise automated?

3. I have observed that the last test fails (yesterday, but not today!), because the namespace it tries to create already exists. I believe this is because it is pending deletion.

   My work-around is as follows:

ovs_add_netns_and_veths () { info "Adding netns attached: sbx:$1 dp:$2 {$3, $4, $5}"

• for i in $(seq 10); do

• ovs_sbx "$1" test -e "/var/run/netns/$3" || break
  

• info "Namespace $3 still exists (attempt $i)"
  

• ovs_sbx "$1" ip netns del "$3"
  

• sleep "$i"
  

• done ovs_sbx "$1" ip netns add "$3" || return 1 on_exit "ovs_sbx $1 ip netns del $3" ovs_sbx "$1" ip link add "$4" type veth peer name "$5" || return 1

  N.B.: the "netns del" part is probably not needed, but I'm not able to exercise it effectively right now.

  I am wondering if a loop like this is appropriate to add, perhaps also to namespace deletion. Or if it would be appropriate to port openvswitch.sh to use ./tools/testing/selftests/net/lib.sh, which I believe handles this.

4. I am observing timeouts whith the default value of 45s. Bumping this to 90s seems to help. Are there any objections to a patch to bump the timeout?

5. openvswitch.sh starts with "#!/bin/sh". But substitutions such as "${ns:0:1}0" fail if /bin/sh is dash. Perhaps we should change openvswitch.sh to use bash?