[PATCH net-next 4/4] netconsole: selftest: verify userdata entry limit

[Breno Leitao <leitao@debian.org>]

Add a new selftest for netconsole that tests the userdata entry limit
functionality. The test performs two key verifications:

1. Create MAX_USERDATA_ITEMS (16) userdata entries successfully
2. Confirm that attempting to create an additional userdata entry fails

The selftest script uses the netcons library and checks the behavior
by attempting to create entries beyond the maximum allowed limit.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 MAINTAINERS                                        |  2 +-
 .../selftests/drivers/net/netcons_overflow.sh      | 67 ++++++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8af5c9a28e68c4b6a785e2e6b82db20b3cf59822..62192db4641a4056d1eab911f5c141fb37eaed36 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16092,7 +16092,7 @@ S:	Maintained
 F:	Documentation/networking/netconsole.rst
 F:	drivers/net/netconsole.c
 F:	tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
-F:	tools/testing/selftests/drivers/net/netcons_basic.sh
+F:	tools/testing/selftests/drivers/net/netcons\*
 
 NETDEVSIM
 M:	Jakub Kicinski <kuba@kernel.org>
diff --git a/tools/testing/selftests/drivers/net/netcons_overflow.sh b/tools/testing/selftests/drivers/net/netcons_overflow.sh
new file mode 100755
index 0000000000000000000000000000000000000000..a19f613553578dc185b7332a827463d9b0c6685f
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_overflow.sh
@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+#  This test verifies that users can successfully create up to
+#  MAX_USERDATA_ITEMS userdata entries without encountering any failures.
+#
+#  Additionally, it tests for expected failure when attempting to exceed this
+#  maximum limit.
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+# This is coming from netconsole code. Check for it in drivers/net/netconsole.c
+MAX_USERDATA_ITEMS=16
+
+# Function to create userdata entries
+function create_userdata_max_entries() {
+	# All these keys should be created without any error
+	for i in $(seq $MAX_USERDATA_ITEMS)
+	do
+		# USERDATA_KEY is used by set_user_data
+		USERDATA_KEY="key"${i}
+		set_user_data
+	done
+}
+
+# Function to verify the entry limit
+function verify_entry_limit() {
+	# Allowing the test to fail without exiting, since the next command
+	# will fail
+	set +e
+	mkdir "${NETCONS_PATH}/userdata/key_that_will_fail" 2> /dev/null
+	ret="$?"
+	set -e
+	if [ "$ret" -eq 0 ];
+	then
+		echo "Adding more than ${MAX_USERDATA_ITEMS} entries in userdata should fail, but it didn't" >&2
+		ls "${NETCONS_PATH}/userdata/" >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# ========== #
+# Start here #
+# ========== #
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup EXIT
+# Create one namespace and two interfaces
+set_network
+# Create a dynamic target for netconsole
+create_dynamic_target
+# populate the maximum number of supported keys in userdata
+create_userdata_max_entries
+# Verify an additional entry is not allowed
+verify_entry_limit
+exit "${ksft_pass}"

-- 
2.43.5