selftests: net: add netconsole test for cmdline configuration

Add a new selftest to verify netconsole module loading with command
line arguments. This test exercises the init_netconsole() path and
validates proper parsing of the netconsole= parameter format.

The test:
- Loads netconsole module with cmdline configuration instead of
  dynamic reconfiguration
- Validates message transmission through the configured target
- Adds helper functions for cmdline string generation and module
  validation

This complements existing netconsole selftests by covering the
module initialization code path that processes boot-time parameters.
This test is useful to test issues like the one described in [1].

Link: https://lore.kernel.org/netdev/Z36TlACdNMwFD7wv@dev-ushankar.dev.purestorage.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250613-rework-v3-8-0752bf2e6912@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index be780bcb73a3bcd7bb47ea48c7efd72f93ea50ef..bd309b2d39095768b1b7ee3f0c7a69c7df0a14f4 100644 (file)
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -12,6 +12,7 @@ TEST_GEN_FILES := \
 TEST_PROGS := \
        napi_id.py \
        netcons_basic.sh \
+       netcons_cmdline.sh \
        netcons_fragmented_msg.sh \
        netcons_overflow.sh \
        netcons_sysdata.sh \

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 598279139a6e548d1ca395b287e3c0d3a4935397..3fcf85a3459698d397cfffe37eb0de8a79e2576a 100644 (file)
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -121,6 +121,17 @@ function create_dynamic_target() {
        echo 1 > "${NETCONS_PATH}"/enabled
 }
 
+# Generate the command line argument for netconsole following:
+#  netconsole=[+][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]
+function create_cmdline_str() {
+       DSTMAC=$(ip netns exec "${NAMESPACE}" \
+                ip link show "${DSTIF}" | awk '/ether/ {print $2}')
+       SRCPORT="1514"
+       TGTPORT="6666"
+
+       echo "netconsole=\"+${SRCPORT}@${SRCIP}/${SRCIF},${TGTPORT}@${DSTIP}/${DSTMAC}\""
+}
+
 # Do not append the release to the header of the message
 function disable_release_append() {
        echo 0 > "${NETCONS_PATH}"/enabled
@@ -173,13 +184,9 @@ function listen_port_and_save_to() {
                socat UDP-LISTEN:"${PORT}",fork "${OUTPUT}"
 }
 
-function validate_result() {
+# Only validate that the message arrived properly
+function validate_msg() {
        local TMPFILENAME="$1"
-       local FORMAT=${2:-"extended"}
-
-       # TMPFILENAME will contain something like:
-       # 6.11.1-0_fbk0_rc13_509_g30d75cea12f7,13,1822,115075213798,-;netconsole selftest: netcons_gtJHM
-       #  key=value
 
        # Check if the file exists
        if [ ! -f "$TMPFILENAME" ]; then
@@ -192,6 +199,17 @@ function validate_result() {
                cat "${TMPFILENAME}" >&2
                exit "${ksft_fail}"
        fi
+}
+
+# Validate the message and userdata
+function validate_result() {
+       local TMPFILENAME="$1"
+
+       # TMPFILENAME will contain something like:
+       # 6.11.1-0_fbk0_rc13_509_g30d75cea12f7,13,1822,115075213798,-;netconsole selftest: netcons_gtJHM
+       #  key=value
+
+       validate_msg "${TMPFILENAME}"
 
        # userdata is not supported on basic format target,
        # thus, do not validate it.
@@ -267,3 +285,12 @@ function pkill_socat() {
        pkill -f "${PROCESS_NAME}"
        set -e
 }
+
+# Check if netconsole was compiled as a module, otherwise exit
+function check_netconsole_module() {
+       if modinfo netconsole | grep filename: | grep -q builtin
+       then
+               echo "SKIP: netconsole should be compiled as a module" >&2
+               exit "${ksft_skip}"
+       fi
+}

diff --git a/tools/testing/selftests/drivers/net/netcons_cmdline.sh b/tools/testing/selftests/drivers/net/netcons_cmdline.sh
new file mode 100755 (executable)
index 0000000..ad2fb8b
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_cmdline.sh
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This is a selftest to test cmdline arguments on netconsole.
+# It exercises loading of netconsole from cmdline instead of the dynamic
+# reconfiguration. This includes parsing the long netconsole= line and all the
+# flow through init_netconsole().
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+
+check_netconsole_module
+
+modprobe netdevsim 2> /dev/null || true
+rmmod netconsole 2> /dev/null || true
+
+# The content of kmsg will be save to the following file
+OUTPUT_FILE="/tmp/${TARGET}"
+
+# Check for basic system dependency and exit if not found
+# check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace and network interfaces
+trap do_cleanup EXIT
+# Create one namespace and two interfaces
+set_network
+# Create the command line for netconsole, with the configuration from the
+# function above
+CMDLINE="$(create_cmdline_str)"
+
+# Load the module, with the cmdline set
+modprobe netconsole "${CMDLINE}"
+
+# Listed for netconsole port inside the namespace and destination interface
+listen_port_and_save_to "${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 "${OUTPUT_FILE}"
+# Make sure the message was received in the dst part
+# and exit
+validate_msg "${OUTPUT_FILE}"
+
+exit "${ksft_pass}"