netdev - Re: [PATCH net v3 2/2] selftests: Add IPv6 link-local address generation tests for GRE devices.

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Message-ID: <d1e3d6a6-90b8-45bd-a57f-c8175d0bd906@redhat.com>
Date: Thu, 27 Feb 2025 13:33:25 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Guillaume Nault <gnault@...hat.com>, David Miller <davem@...emloft.net>,
 Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>
Cc: netdev@...r.kernel.org, Simon Horman <horms@...nel.org>,
 David Ahern <dsahern@...nel.org>, Antonio Quartulli <antonio@...delbit.com>,
 Ido Schimmel <idosch@...sch.org>
Subject: Re: [PATCH net v3 2/2] selftests: Add IPv6 link-local address
 generation tests for GRE devices.

On 2/25/25 3:43 PM, Guillaume Nault wrote:
> diff --git a/tools/testing/selftests/net/gre_ipv6_lladdr.sh b/tools/testing/selftests/net/gre_ipv6_lladdr.sh
> new file mode 100755
> index 000000000000..85e40b6df55e
> --- /dev/null
> +++ b/tools/testing/selftests/net/gre_ipv6_lladdr.sh
> @@ -0,0 +1,227 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +
> +ERR=4 # Return 4 by default, which is the SKIP code for kselftest
> +PAUSE_ON_FAIL="no"
> +
> +readonly NS0=$(mktemp -u ns0-XXXXXXXX)
> +
> +# Exit the script after having removed the network namespaces it created
> +#
> +# Parameters:
> +#
> +#   * The list of network namespaces to delete before exiting.
> +#
> +exit_cleanup()
> +{
> +	for ns in "$@"; do
> +		ip netns delete "${ns}" 2>/dev/null || true
> +	done
> +
> +	if [ "${ERR}" -eq 4 ]; then
> +		echo "Error: Setting up the testing environment failed." >&2
> +	fi
> +
> +	exit "${ERR}"

I'm sorry for the late feedback, but if you use the helper from lib.sh
you could avoid some code duplication for ns setup and cleanup.

> +}
> +
> +# Create the network namespaces used by the script (NS0)
> +#
> +create_namespaces()
> +{
> +	ip netns add "${NS0}" || exit_cleanup

Also no need to check for failures at this point. If there is no
namespace support most/all selftests will fail badly

> +}
> +
> +# The trap function handler
> +#
> +exit_cleanup_all()
> +{
> +	exit_cleanup "${NS0}"
> +}
> +
> +# Add fake IPv4 and IPv6 networks on the loopback device, to be used as
> +# underlay by future GRE devices.
> +#
> +setup_basenet()
> +{
> +	ip -netns "${NS0}" link set dev lo up
> +	ip -netns "${NS0}" address add dev lo 192.0.2.10/24
> +	ip -netns "${NS0}" address add dev lo 2001:db8::10/64 nodad
> +}
> +
> +# Check if network device has an IPv6 link-local address assigned.
> +#
> +# Parameters:
> +#
> +#   * $1: The network device to test
> +#   * $2: An extra regular expression that should be matched (to verify the
> +#         presence of extra attributes)
> +#   * $3: The expected return code from grep (to allow checking the abscence of
> +#         a link-local address)
> +#   * $4: The user visible name for the scenario being tested
> +#
> +check_ipv6_ll_addr()
> +{
> +	local DEV="$1"
> +	local EXTRA_MATCH="$2"
> +	local XRET="$3"
> +	local MSG="$4"
> +	local RET
> +
> +	printf "%-75s  " "${MSG}"
> +
> +	set +e
> +	ip -netns "${NS0}" -6 address show dev "${DEV}" scope link | grep "fe80::" | grep -q "${EXTRA_MATCH}"
> +	RET=$?
> +	set -e
> +
> +	if [ "${RET}" -eq "${XRET}" ]; then
> +		printf "[ OK ]\n"

You can use check_err / log_test from lib.sh to reduce code duplication
with other tests and more consistent output.

> +	else
> +		ERR=1
> +		printf "[FAIL]\n"
> +		if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
> +			printf "\nHit enter to continue, 'q' to quit\n"
> +			read -r a
> +			if [ "$a" = "q" ]; then
> +				exit 1
> +			fi
> +		fi

I guess something like this could be placed into lib.sh, but that would
be net-next material

Thanks,

Paolo