[PATCH v2 03/14] kunit: Add test cases for backtrace warning suppression

[Guenter Roeck <linux@xxxxxxxxxxxx>]

Add unit tests to verify that warning backtrace suppression works.

If backtrace suppression does _not_ work, the unit tests will likely
trigger unsuppressed backtraces, which should actually help to get
the affected architectures / platforms fixed.

Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
Acked-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
- Rebased to v6.9-rc1
- Added Tested-by:, Acked-by:, and Reviewed-by: tags
- Introduced KUNIT_SUPPRESS_BACKTRACE configuration option

 lib/kunit/Makefile                     |   7 +-
 lib/kunit/backtrace-suppression-test.c | 104 +++++++++++++++++++++++++
 2 files changed, 109 insertions(+), 2 deletions(-)
 create mode 100644 lib/kunit/backtrace-suppression-test.c

diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
index 545b57c3be48..3eee1bd0ce5e 100644
--- a/lib/kunit/Makefile
+++ b/lib/kunit/Makefile
@@ -16,10 +16,13 @@ endif
 
 # KUnit 'hooks' and bug handling are built-in even when KUnit is built
 # as a module.
-obj-y +=				hooks.o \
-					bug.o
+obj-y +=				hooks.o
+obj-$(CONFIG_KUNIT_SUPPRESS_BACKTRACE) += bug.o
 
 obj-$(CONFIG_KUNIT_TEST) +=		kunit-test.o
+ifeq ($(CCONFIG_KUNIT_SUPPRESS_BACKTRACE),y)
+obj-$(CONFIG_KUNIT_TEST) +=		backtrace-suppression-test.o
+endif
 
 # string-stream-test compiles built-in only.
 ifeq ($(CONFIG_KUNIT_TEST),y)
diff --git a/lib/kunit/backtrace-suppression-test.c b/lib/kunit/backtrace-suppression-test.c
new file mode 100644
index 000000000000..47c619283802
--- /dev/null
+++ b/lib/kunit/backtrace-suppression-test.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for suppressing warning tracebacks
+ *
+ * Copyright (C) 2024, Guenter Roeck
+ * Author: Guenter Roeck <linux@xxxxxxxxxxxx>
+ */
+
+#include <kunit/test.h>
+#include <linux/bug.h>
+
+static void backtrace_suppression_test_warn_direct(struct kunit *test)
+{
+	DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct);
+
+	START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct);
+	WARN(1, "This backtrace should be suppressed");
+	END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct);
+
+	KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_direct), 1);
+}
+
+static void trigger_backtrace_warn(void)
+{
+	WARN(1, "This backtrace should be suppressed");
+}
+
+static void backtrace_suppression_test_warn_indirect(struct kunit *test)
+{
+	DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn);
+
+	START_SUPPRESSED_WARNING(trigger_backtrace_warn);
+	trigger_backtrace_warn();
+	END_SUPPRESSED_WARNING(trigger_backtrace_warn);
+
+	KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn), 1);
+}
+
+static void backtrace_suppression_test_warn_multi(struct kunit *test)
+{
+	DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn);
+	DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi);
+
+	START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi);
+	START_SUPPRESSED_WARNING(trigger_backtrace_warn);
+	WARN(1, "This backtrace should be suppressed");
+	trigger_backtrace_warn();
+	END_SUPPRESSED_WARNING(trigger_backtrace_warn);
+	END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi);
+
+	KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_multi), 1);
+	KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn), 1);
+}
+
+static void backtrace_suppression_test_warn_on_direct(struct kunit *test)
+{
+	DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct);
+
+	if (!IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE) && !IS_ENABLED(CONFIG_KALLSYMS))
+		kunit_skip(test, "requires CONFIG_DEBUG_BUGVERBOSE or CONFIG_KALLSYMS");
+
+	START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct);
+	WARN_ON(1);
+	END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct);
+
+	KUNIT_EXPECT_EQ(test,
+			SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_on_direct), 1);
+}
+
+static void trigger_backtrace_warn_on(void)
+{
+	WARN_ON(1);
+}
+
+static void backtrace_suppression_test_warn_on_indirect(struct kunit *test)
+{
+	DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn_on);
+
+	if (!IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE))
+		kunit_skip(test, "requires CONFIG_DEBUG_BUGVERBOSE");
+
+	START_SUPPRESSED_WARNING(trigger_backtrace_warn_on);
+	trigger_backtrace_warn_on();
+	END_SUPPRESSED_WARNING(trigger_backtrace_warn_on);
+
+	KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn_on), 1);
+}
+
+static struct kunit_case backtrace_suppression_test_cases[] = {
+	KUNIT_CASE(backtrace_suppression_test_warn_direct),
+	KUNIT_CASE(backtrace_suppression_test_warn_indirect),
+	KUNIT_CASE(backtrace_suppression_test_warn_multi),
+	KUNIT_CASE(backtrace_suppression_test_warn_on_direct),
+	KUNIT_CASE(backtrace_suppression_test_warn_on_indirect),
+	{}
+};
+
+static struct kunit_suite backtrace_suppression_test_suite = {
+	.name = "backtrace-suppression-test",
+	.test_cases = backtrace_suppression_test_cases,
+};
+kunit_test_suites(&backtrace_suppression_test_suite);
+
+MODULE_LICENSE("GPL");
-- 
2.39.2