[PATCH net-next v2 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>
Tested-by: Simon Horman <horms@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
---
 MAINTAINERS                                        |  2 +-
 tools/testing/selftests/drivers/net/Makefile       |  1 +
 .../selftests/drivers/net/netcons_overflow.sh      | 67 ++++++++++++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index d7af1c38dbab0c1ac253ced11a07ee7422c75c0a..d14bfb5ab0122f0b6651e72add3b178dcf742f18 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16175,7 +16175,7 @@ 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/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 0fec8f9801ad4d94d99ab6d0acaea6e2e7b2894d..bcd630eb072eb9cf22bb11a647de751795de2408 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -6,6 +6,7 @@ TEST_INCLUDES := $(wildcard lib/py/*.py) \
 
 TEST_PROGS := \
 	netcons_basic.sh \
+	netcons_overflow.sh \
 	ping.py \
 	queues.py \
 	stats.py \
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..29bad56448a24a2d98c21bd53b74f3bc2ca7e64a
--- /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