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

Paolo Abeni [off-list ref] writes:

On 2/25/25 3:43 PM, Guillaume Nault wrote:

quoted

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.

quoted

+}
+
+# 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

quoted

+}
+
+# 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.

quoted

+	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

The pause-on-fail bits? lib.sh has them as pause_on_fail(). log_test()
invokes them on FAIL an XFAIL results.

FWIW, this is untested, but with lib.sh, I think it would be:

check_ipv6_ll_addr()
{
	local DEV="$1"
	local EXTRA_MATCH="$2"
	local XRET="$3"
	local MSG="$4"

	RET=0
        set +e
	ip -netns "${NS0}" -6 address show dev "${DEV}" scope link | grep "fe80::" | grep -q "${EXTRA_MATCH}"
        check_err_fail $XRET $? ""
        log_test "${MSG}"
        set -e
}

The set +e domain needs to extend over log_test() as well, because that
at one point calls log_test_result() with one fewer argument, and the
shift in there produces a non-zero exit code.