netconsole: selftests: Move netconsole selftests to separate target

This patch moves netconsole selftests from drivers/net to its own target
in drivers/net/netconsole.

This change helps saving some resources from CI since tests in
drivers/net automatically run against real hardware which are not used
by netconsole tests as they rely solely on netdevsim.

lib_netcons.sh is kept under drivers/net/lib since it is also used by
bonding selftests. Finally, drivers/net config remains unchanged as
netpoll_basic.py requires netconsole (and does leverage real HW testing).

Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Andre Carvalho <asantostc@gmail.com>
Link: https://patch.msgid.link/20260127-netcons-selftest-target-v2-1-f509ab65b3bc@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This test creates two netdevsim virtual interfaces, assigns one of them (the
+# "destination interface") to a new namespace, and assigns IP addresses to both
+# interfaces.
+#
+# It listens on the destination interface using socat and configures a dynamic
+# target on netconsole, pointing to the destination IP address.
+#
+# Finally, it checks whether the message was received properly on the
+# destination interface.  Note that this test may pollute the kernel log buffer
+# (dmesg) and relies on dynamic configuration and namespaces being configured.
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/../lib/sh/lib_netcons.sh
+
+modprobe netdevsim 2> /dev/null || true
+modprobe 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
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup EXIT
+
+# Run the test twice, with different format modes
+for FORMAT in "basic" "extended"
+do
+	for IP_VERSION in "ipv6" "ipv4"
+	do
+		echo "Running with target mode: ${FORMAT} (${IP_VERSION})"
+		# Set current loglevel to KERN_INFO(6), and default to
+		# KERN_NOTICE(5)
+		echo "6 5" > /proc/sys/kernel/printk
+		# 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}" "${FORMAT}"
+		# kill socat in case it is still running
+		pkill_socat
+		cleanup
+		echo "${FORMAT} : ${IP_VERSION} : Test passed" >&2
+	done
+done
+
+trap - EXIT
+exit "${ksft_pass}"