Subject: Re: [PATCH net-next v4 02/10] selftests: net: add helpers for running a command on other targets

From: Petr Machata <[email-masked]>
Date: Mon, 30 Mar 2026 13:02:12 +0200

Ioana Ciornei <[email-masked]> writes:

> Add a couple of helpers which can be used by tests which need to run a
> specific bash command on a different target than the local system, be it
> either another netns or a remote system accessible through ssh.
>
> The __run_on() function is passed through $1 the target on which the
> command should be executed while run_on() is passed the name of the
> interface that is then used to retrieve the target from the TARGETS
> array.
>
> Signed-off-by: Ioana Ciornei <[email-masked]>
> ---
> Changes in v4:
> - reworked the helpers so that no global variable is used and
>   information is passed only through parameters
> Changes in v3:
> - s/TARGET/CUR_TARGET
> - always fallback on running a command locally when either TARGETS is
>   not declared or there is no entry for a specific interface
> Changes in v2:
> - patch is new
>
>  tools/testing/selftests/net/lib.sh | 38 ++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/tools/testing/selftests/net/lib.sh b/tools/testing/selftests/net/lib.sh
> index b40694573f4c..6c0d613a4de5 100644
> --- a/tools/testing/selftests/net/lib.sh
> +++ b/tools/testing/selftests/net/lib.sh
> @@ -670,3 +670,41 @@ cmd_jq()
>  	# return success only in case of non-empty output
>  	[ ! -z "$output" ]
>  }
> +
> +__run_on()
> +{
> +	local target=$1; shift
> +	local type args
> +
> +	IFS=':' read -r type args <<< "$target"
> +
> +	case "$type" in
> +	netns)
> +		# Execute command in network namespace
> +		# args contains the namespace name
> +		ip netns exec "$args" "$@"
> +		;;
> +	ssh)
> +		# Execute command via SSH args contains user@host
> +		ssh -n "$args" "$@"
> +		;;
> +	local|*)
> +		# Execute command locally. This is also the fallback
> +		# case for when the interface's target is not found in
> +		# the TARGETS array.
> +		"$@"
> +		;;
> +	esac
> +}
> +
> +run_on()
> +{
> +	local iface=$1; shift
> +	local target="local:"
> +
> +	if declare -p TARGETS &>/dev/null; then
> +		target="${TARGETS[$iface]}"

So I think Jakub's runs fail because there's a shell export somewhere
that gets inherited through make to the launched test. I guess it would
be enough for the test to validate that TARGETS is an array, because
those don't get inherited.

Is there a reason not to reuse DRIVER_TEST_CONFORMANT as a tell though?

> +	fi
> +
> +	__run_on "$target" "$@"
> +}

Does the latter helper need to be in net/lib.sh? Since it uses TARGETS,
which are a forwarding/lib.sh concept, it seems misplaced there.