selftests: net: Add IPv6 support to netconsole basic tests

Add IPv6 support to the netconsole basic functionality tests by:

- Introducing separate IPv4 and IPv6 address variables (SRCIP4/SRCIP6,
  DSTIP4/DSTIP6) to replace the single SRCIP/DSTIP variables
- Adding select_ipv4_or_ipv6() function to choose protocol version
- Updating socat configuration to use UDP6-LISTEN for IPv6 tests
- Adding wait_for_port() wrapper to handle protocol-specific port waiting
- Expanding test matrix to run both basic and extended formats against
  both IPv4 and IPv6 protocols
- Improving cleanup to kill any remaining socat processes
- Adding sleep delays for better IPv6 packet handling reliability

The test now validates netconsole functionality across both IP versions,
improving test coverage for dual-stack network environments.

This test would avoid the regression fixed by commit f599020702 ("net:
netpoll: Initialize UDP checksum field before checksumming")

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250702-netpoll_untagle_ip-v2-7-13cf3db24e2b@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh

@@ -11,9 +11,11 @@ set -euo pipefail
 LIBDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
 
 SRCIF="" # to be populated later
-SRCIP=192.0.2.1
+SRCIP4="192.0.2.1"
+SRCIP6="fc00::1"
 DSTIF="" # to be populated later
-DSTIP=192.0.2.2
+DSTIP4="192.0.2.2"
+DSTIP6="fc00::2"
 
 PORT="6666"
 MSG="netconsole selftest"
@@ -80,7 +82,23 @@ function configure_ip() {
 	ip link set "${SRCIF}" up
 }
 
+function select_ipv4_or_ipv6()
+{
+	local VERSION=${1}
+
+	if [[ "$VERSION" == "ipv6" ]]
+	then
+		DSTIP="${DSTIP6}"
+		SRCIP="${SRCIP6}"
+	else
+		DSTIP="${DSTIP4}"
+		SRCIP="${SRCIP4}"
+	fi
+}
+
 function set_network() {
+	local IP_VERSION=${1:-"ipv4"}
+
 	# setup_ns function is coming from lib.sh
 	setup_ns NAMESPACE
 
@@ -91,6 +109,7 @@ function set_network() {
 	# Link both interfaces back to back
 	link_ifaces
 
+	select_ipv4_or_ipv6 "${IP_VERSION}"
 	configure_ip
 }
 
@@ -119,6 +138,11 @@ function create_dynamic_target() {
 	fi
 
 	echo 1 > "${NETCONS_PATH}"/enabled
+
+	# This will make sure that the kernel was able to
+	# load the netconsole driver configuration. The console message
+	# gets more organized/sequential as well.
+	sleep 1
 }
 
 # Generate the command line argument for netconsole following:
@@ -179,9 +203,18 @@ function set_user_data() {
 
 function listen_port_and_save_to() {
 	local OUTPUT=${1}
+	local IPVERSION=${2:-"ipv4"}
+
+	if [ "${IPVERSION}" == "ipv4" ]
+	then
+		SOCAT_MODE="UDP-LISTEN"
+	else
+		SOCAT_MODE="UDP6-LISTEN"
+	fi
+
 	# Just wait for 2 seconds
 	timeout 2 ip netns exec "${NAMESPACE}" \
-		socat UDP-LISTEN:"${PORT}",fork "${OUTPUT}"
+		socat "${SOCAT_MODE}":"${PORT}",fork "${OUTPUT}"
 }
 
 # Only validate that the message arrived properly
@@ -263,8 +296,15 @@ function check_for_dependencies() {
 		exit "${ksft_skip}"
 	fi
 
-	if ip addr list | grep -E "inet.*(${SRCIP}|${DSTIP})" 2> /dev/null; then
-		echo "SKIP: IPs already in use. Skipping it" >&2
+	REGEXP4="inet.*(${SRCIP4}|${DSTIP4})"
+	REGEXP6="inet.*(${SRCIP6}|${DSTIP6})"
+	if ip addr list | grep -E "${REGEXP4}" 2> /dev/null; then
+		echo "SKIP: IPv4s already in use. Skipping it" >&2
+		exit "${ksft_skip}"
+	fi
+
+	if ip addr list | grep -E "${REGEXP6}" 2> /dev/null; then
+		echo "SKIP: IPv6s already in use. Skipping it" >&2
 		exit "${ksft_skip}"
 	fi
 }
@@ -278,11 +318,13 @@ function check_for_taskset() {
 
 # This is necessary if running multiple tests in a row
 function pkill_socat() {
-	PROCESS_NAME="socat UDP-LISTEN:6666,fork ${OUTPUT_FILE}"
+	PROCESS_NAME4="socat UDP-LISTEN:6666,fork ${OUTPUT_FILE}"
+	PROCESS_NAME6="socat UDP6-LISTEN:6666,fork ${OUTPUT_FILE}"
 	# socat runs under timeout(1), kill it if it is still alive
 	# do not fail if socat doesn't exist anymore
 	set +e
-	pkill -f "${PROCESS_NAME}"
+	pkill -f "${PROCESS_NAME4}"
+	pkill -f "${PROCESS_NAME6}"
 	set -e
 }
 
@@ -294,3 +336,23 @@ function check_netconsole_module() {
 		exit "${ksft_skip}"
 	fi
 }
+
+# A wrapper to translate protocol version to udp version
+function wait_for_port() {
+	local NAMESPACE=${1}
+	local PORT=${2}
+	IP_VERSION=${3}
+
+	if [ "${IP_VERSION}" == "ipv6" ]
+	then
+		PROTOCOL="udp6"
+	else
+		PROTOCOL="udp"
+	fi
+
+	wait_local_port_listen "${NAMESPACE}" "${PORT}" "${PROTOCOL}"
+	# even after the port is open, let's wait 1 second before writing
+	# otherwise the packet could be missed, and the test will fail. Happens
+	# more frequently on IPv6
+	sleep 1
+}

tools/testing/selftests/drivers/net/netcons_basic.sh

@@ -36,30 +36,37 @@ trap cleanup EXIT
 # Run the test twice, with different format modes
 for FORMAT in "basic" "extended"
 do
-	echo "Running with target mode: ${FORMAT}"
-	# Create one namespace and two interfaces
-	set_network
-	# Create a dynamic target for netconsole
-	create_dynamic_target "${FORMAT}"
-	# Only set userdata for extended format
-	if [ "$FORMAT" == "extended" ]
-	then
-		# Set userdata "key" with the "value" value
-		set_user_data
-	fi
-	# Listed for netconsole port inside the namespace and destination interface
-	listen_port_and_save_to "${OUTPUT_FILE}" &
-	# Wait for socat to start and listen to the port.
-	wait_local_port_listen "${NAMESPACE}" "${PORT}" udp
-	# Send the message
-	echo "${MSG}: ${TARGET}" > /dev/kmsg
-	# Wait until socat saves the file to disk
-	busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
+	for IP_VERSION in "ipv6" "ipv4"
+	do
+		echo "Running with target mode: ${FORMAT} (${IP_VERSION})"
+		# Create one namespace and two interfaces
+		set_network "${IP_VERSION}"
+		# Create a dynamic target for netconsole
+		create_dynamic_target "${FORMAT}"
+		# Only set userdata for extended format
+		if [ "$FORMAT" == "extended" ]
+		then
+			# Set userdata "key" with the "value" value
+			set_user_data
+		fi
+		# Listed for netconsole port inside the namespace and
+		# destination interface
+		listen_port_and_save_to "${OUTPUT_FILE}" "${IP_VERSION}" &
+		# Wait for socat to start and listen to the port.
+		wait_for_port "${NAMESPACE}" "${PORT}" "${IP_VERSION}"
+		# Send the message
+		echo "${MSG}: ${TARGET}" > /dev/kmsg
+		# Wait until socat saves the file to disk
+		busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
 
-	# Make sure the message was received in the dst part
-	# and exit
-	validate_result "${OUTPUT_FILE}" "${FORMAT}"
-	cleanup
+		# Make sure the message was received in the dst part
+		# and exit
+		validate_result "${OUTPUT_FILE}" "${FORMAT}"
+		# kill socat in case it is still running
+		pkill_socat
+		cleanup
+		echo "${FORMAT} : ${IP_VERSION} : Test passed" >&2
+	done
 done
 
 trap - EXIT