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

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Message-ID: <20240424173715.GP42092@kernel.org>
Date: Wed, 24 Apr 2024 18:37:16 +0100
From: Simon Horman <horms@...nel.org>
To: Aaron Conole <aconole@...hat.com>, Jakub Kicinski <kuba@...nel.org>
Cc: dev@...nvswitch.org, netdev@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: 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?