[PATCH RFC net-next v3 7/8] netconsole: selftest: test for sysdata CPU

[Breno Leitao <leitao@debian.org>]

Add a new selftest to verify that the netconsole module correctly
handles CPU runtime data in sysdata. The test validates three scenarios:

1. Basic CPU sysdata functionality - verifies that cpu=X is appended to
   messages
2. CPU sysdata with userdata - ensures CPU data works alongside userdata
3. Disabled CPU sysdata - confirms no CPU data is included when disabled

The test uses taskset to control which CPU sends messages and verifies
the reported CPU matches the one used. This helps ensure that netconsole
accurately tracks and reports the originating CPU of messages.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 tools/testing/selftests/drivers/net/Makefile       |   1 +
 .../selftests/drivers/net/lib/sh/lib_netcons.sh    |  17 +++
 .../selftests/drivers/net/netcons_sysdata.sh       | 167 +++++++++++++++++++++
 3 files changed, 185 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 137470bdee0c7fd2517bd1baafc12d575de4b4ac..6c5e6159d8913e7bfd6bd835f0a9bd9e9d83518b 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -8,6 +8,7 @@ TEST_INCLUDES := $(wildcard lib/py/*.py) \
 TEST_PROGS := \
 	netcons_basic.sh \
 	netcons_overflow.sh \
+	netcons_sysdata.sh \
 	ping.py \
 	queues.py \
 	stats.py \
diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
index 3acaba41ac7b21aa2fd8457ed640a5ac8a41bc12..d319d177ce5ed7a1b196e68bffe549d57011fb15 100644
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -223,3 +223,20 @@ function check_for_dependencies() {
 		exit "${ksft_skip}"
 	fi
 }
+
+function check_for_taskset() {
+	if ! which taskset > /dev/null ; then
+		echo "SKIP: taskset(1) is not available" >&2
+		exit "${ksft_skip}"
+	fi
+}
+
+# This is necessary if running multiple tests in a row
+function pkill_socat() {
+	PROCESS_NAME="socat UDP-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}"
+	set -e
+}
diff --git a/tools/testing/selftests/drivers/net/netcons_sysdata.sh b/tools/testing/selftests/drivers/net/netcons_sysdata.sh
new file mode 100755
index 0000000000000000000000000000000000000000..f50ccae6c0c090d6574defe5e02d7eda5f3d7188
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_sysdata.sh
@@ -0,0 +1,167 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# A test that makes sure that sysdata runtime CPU data is properly set
+# when a message is sent.
+#
+# There are 3 different tests, every time sent using a random CPU.
+#  - Test #1
+#    * Only enable cpu_nr sysdata feature.
+#  - Test #2
+#    * Keep cpu_nr sysdata feature enable and enable userdata.
+#  - Test #3
+#    * keep userdata enabled, and disable sysdata cpu_nr feature.
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+
+# Enable the sysdata cpu_nr feature
+function set_cpu_nr() {
+	if [[ ! -f "${NETCONS_PATH}/userdata/cpu_nr" ]]
+	then
+		echo "Populate CPU configfs path not available in ${NETCONS_PATH}/userdata/cpu_nr" >&2
+		exit "${ksft_skip}"
+	fi
+
+	echo 1 > "${NETCONS_PATH}/userdata/cpu_nr"
+}
+
+# Disable the sysdata cpu_nr feature
+function unset_cpu_nr() {
+	echo 0 > "${NETCONS_PATH}/userdata/cpu_nr"
+}
+
+# Test if MSG content and `cpu=${CPU}` exists in OUTPUT_FILE
+function validate_sysdata_cpu_exists() {
+	# OUTPUT_FILE will contain something like:
+	# 6.11.1-0_fbk0_rc13_509_g30d75cea12f7,13,1822,115075213798,-;netconsole selftest: netcons_gtJHM
+	#  userdatakey=userdatavalue
+	#  cpu=X
+
+	if [ ! -f "$OUTPUT_FILE" ]; then
+		echo "FAIL: File was not generated." >&2
+		exit "${ksft_fail}"
+	fi
+
+	if ! grep -q "${MSG}" "${OUTPUT_FILE}"; then
+		echo "FAIL: ${MSG} not found in ${OUTPUT_FILE}" >&2
+		cat "${OUTPUT_FILE}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	# Check if cpu=XX exists in the file and matches the one used
+	# in taskset(1)
+	if ! grep -q "cpu=${CPU}\+" "${OUTPUT_FILE}"; then
+		echo "FAIL: 'cpu=${CPU}' not found in ${OUTPUT_FILE}" >&2
+		cat "${OUTPUT_FILE}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	rm "${OUTPUT_FILE}"
+	pkill_socat
+}
+
+# Test if MSG content exists in OUTPUT_FILE but no `cpu=` string
+function validate_sysdata_no_cpu() {
+	if [ ! -f "$OUTPUT_FILE" ]; then
+		echo "FAIL: File was not generated." >&2
+		exit "${ksft_fail}"
+	fi
+
+	if ! grep -q "${MSG}" "${OUTPUT_FILE}"; then
+		echo "FAIL: ${MSG} not found in ${OUTPUT_FILE}" >&2
+		cat "${OUTPUT_FILE}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	if grep -q "cpu=" "${OUTPUT_FILE}"; then
+		echo "FAIL: 'cpu=  found in ${OUTPUT_FILE}" >&2
+		cat "${OUTPUT_FILE}" >&2
+		exit "${ksft_fail}"
+	fi
+
+	rm "${OUTPUT_FILE}"
+}
+
+# Start socat, send the message and wait for the file to show up in the file
+# system
+function runtest {
+	# Listen 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}" "${PORT}" udp
+	# Send the message
+	taskset -c "${CPU}" echo "${MSG}: ${TARGET}" > /dev/kmsg
+	# Wait until socat saves the file to disk
+	busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
+}
+
+# ========== #
+# Start here #
+# ========== #
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# This test also depends on taskset(1). Check for it before starting the test
+check_for_taskset
+
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup EXIT
+# Create one namespace and two interfaces
+set_network
+# Create a dynamic target for netconsole
+create_dynamic_target
+
+#====================================================
+# TEST #1
+# Send message from a random CPU
+#====================================================
+# Random CPU in the system
+CPU=$((RANDOM % $(nproc)))
+OUTPUT_FILE="/tmp/${TARGET}_1"
+MSG="Test #1 from CPU${CPU}"
+# Enable the auto population of cpu_nr
+set_cpu_nr
+runtest
+# Make sure the message was received in the dst part
+# and exit
+validate_sysdata_cpu_exists
+
+#====================================================
+# TEST #2
+# This test now adds userdata together with sysdata
+# ===================================================
+# Get a new random CPU
+CPU=$((RANDOM % $(nproc)))
+OUTPUT_FILE="/tmp/${TARGET}_2"
+MSG="Test #2 from CPU${CPU}"
+set_user_data
+runtest
+validate_sysdata_cpu_exists
+
+# ===================================================
+# TEST #3
+# Unset cpu_nr, so, no CPU should be appended.
+# userdata is still set
+# ===================================================
+CPU=$((RANDOM % $(nproc)))
+OUTPUT_FILE="/tmp/${TARGET}_3"
+MSG="Test #3 from CPU${CPU}"
+# Enable the auto population of cpu_nr
+unset_cpu_nr
+runtest
+# At this time, cpu= shouldn't be present in the msg
+validate_sysdata_no_cpu
+
+exit "${ksft_pass}"

-- 
2.43.5