Subject: Re: [patch net-next v3 3/6] selftests: forwarding: add ability to assemble NETIFS array by driver name

From: Petr Machata <[email-masked]>
Date: Thu, 18 Apr 2024 10:11:12 +0200

Jiri Pirko <[email-masked]> writes:

> From: Jiri Pirko <[email-masked]>
>
> Allow driver tests to work without specifying the netdevice names.
> Introduce a possibility to search for available netdevices according to
> set driver name. Allow test to specify the name by setting
> NETIF_FIND_DRIVER variable.
>
> Note that user overrides this either by passing netdevice names on the
> command line or by declaring NETIFS array in custom forwarding.config
> configuration file.
>
> Signed-off-by: Jiri Pirko <[email-masked]>
> ---
> v1->v2:
> - removed unnecessary "-p" and "-e" options
> - removed unnecessary "! -z" from the check
> - moved NETIF_FIND_DRIVER declaration from the config options
> ---
>  tools/testing/selftests/net/forwarding/lib.sh | 39 +++++++++++++++++++
>  1 file changed, 39 insertions(+)
>
> diff --git a/tools/testing/selftests/net/forwarding/lib.sh b/tools/testing/selftests/net/forwarding/lib.sh
> index 2e7695b94b6b..b3fd0f052d71 100644
> --- a/tools/testing/selftests/net/forwarding/lib.sh
> +++ b/tools/testing/selftests/net/forwarding/lib.sh
> @@ -94,6 +94,45 @@ if [[ ! -v NUM_NETIFS ]]; then
>  	exit $ksft_skip
>  fi
>  
> +##############################################################################
> +# Find netifs by test-specified driver name
> +
> +driver_name_get()
> +{
> +	local dev=$1; shift
> +	local driver_path="/sys/class/net/$dev/device/driver"
> +
> +	if [ ! -L $driver_path ]; then
> +		echo ""
> +	else
> +		basename `realpath $driver_path`
> +	fi

This is just:

	if [[ -L $driver_path ]]; then
		basename `realpath $driver_path`
	fi

> +}
> +
> +find_netif()

Maybe name it find_driver_netif? find_netif sounds super generic.

Also consider having it take an argument instead of accessing
environment NETIF_FIND_DRIVER directly.

> +{
> +	local ifnames=`ip -j link show | jq -r ".[].ifname"`
> +	local count=0
> +
> +	for ifname in $ifnames
> +	do
> +		local driver_name=`driver_name_get $ifname`
> +		if [[ ! -z $driver_name && $driver_name == $NETIF_FIND_DRIVER ]]; then
> +			count=$((count + 1))
> +			NETIFS[p$count]="$ifname"
> +		fi
> +	done
> +}
> +
> +# Whether to find netdevice according to the specified driver.
> +: "${NETIF_FIND_DRIVER:=}"

This would be better placed up there in the Topology description
section. Together with NETIFS and NETIF_NO_CABLE, as it concerns
specification of which interfaces to use.

> +
> +if [[ $NETIF_FIND_DRIVER ]]; then
> +	unset NETIFS
> +	declare -A NETIFS
> +	find_netif
> +fi
> +
>  net_forwarding_dir=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
>  
>  if [[ -f $net_forwarding_dir/forwarding.config ]]; then