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Subject[PATCH v3 1/2] kunit: support failure from dynamic analysis tools
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From: Uriel Guajardo <urielguajardo@google.com>

Add a kunit_fail_current_test() function to fail the currently running
test, if any, with an error message.

This is largely intended for dynamic analysis tools like UBSAN and for
fakes.
E.g. say I had a fake ops struct for testing and I wanted my `free`
function to complain if it was called with an invalid argument, or
caught a double-free. Most return void and have no normal means of
signalling failure (e.g. super_operations, iommu_ops, etc.).

Key points:
* Always update current->kunit_test so anyone can use it.
* commit 83c4e7a0363b ("KUnit: KASAN Integration") only updated it for
CONFIG_KASAN=y

* Create a new header <kunit/test-bug.h> so non-test code doesn't have
to include all of <kunit/test.h> (e.g. lib/ubsan.c)

* Forward the file and line number to make it easier to track down
failures

* Declare the helper function for nice __printf() warnings about mismatched
format strings even when KUnit is not enabled.

Example output from kunit_fail_current_test("message"):
[15:19:34] [FAILED] example_simple_test
[15:19:34] # example_simple_test: initializing
[15:19:34] # example_simple_test: lib/kunit/kunit-example-test.c:24: message
[15:19:34] not ok 1 - example_simple_test

Co-developed-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Uriel Guajardo <urielguajardo@google.com>
Signed-off-by: Daniel Latypov <dlatypov@google.com>
---
include/kunit/test-bug.h | 30 ++++++++++++++++++++++++++++++
lib/kunit/test.c | 37 +++++++++++++++++++++++++++++++++----
2 files changed, 63 insertions(+), 4 deletions(-)
create mode 100644 include/kunit/test-bug.h

diff --git a/include/kunit/test-bug.h b/include/kunit/test-bug.h
new file mode 100644
index 000000000000..18b1034ec43a
--- /dev/null
+++ b/include/kunit/test-bug.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KUnit API allowing dynamic analysis tools to interact with KUnit tests
+ *
+ * Copyright (C) 2020, Google LLC.
+ * Author: Uriel Guajardo <urielguajardo@google.com>
+ */
+
+#ifndef _KUNIT_TEST_BUG_H
+#define _KUNIT_TEST_BUG_H
+
+#define kunit_fail_current_test(fmt, ...) \
+ __kunit_fail_current_test(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
+
+#if IS_ENABLED(CONFIG_KUNIT)
+
+extern __printf(3, 4) void __kunit_fail_current_test(const char *file, int line,
+ const char *fmt, ...);
+
+#else
+
+static __printf(3, 4) void __kunit_fail_current_test(const char *file, int line,
+ const char *fmt, ...)
+{
+}
+
+#endif
+
+
+#endif /* _KUNIT_TEST_BUG_H */
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index ec9494e914ef..5794059505cf 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -7,6 +7,7 @@
*/

#include <kunit/test.h>
+#include <kunit/test-bug.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/sched/debug.h>
@@ -16,6 +17,38 @@
#include "string-stream.h"
#include "try-catch-impl.h"

+/*
+ * Fail the current test and print an error message to the log.
+ */
+void __kunit_fail_current_test(const char *file, int line, const char *fmt, ...)
+{
+ va_list args;
+ int len;
+ char *buffer;
+
+ if (!current->kunit_test)
+ return;
+
+ kunit_set_failure(current->kunit_test);
+
+ /* kunit_err() only accepts literals, so evaluate the args first. */
+ va_start(args, fmt);
+ len = vsnprintf(NULL, 0, fmt, args) + 1;
+ va_end(args);
+
+ buffer = kunit_kmalloc(current->kunit_test, len, GFP_KERNEL);
+ if (!buffer)
+ return;
+
+ va_start(args, fmt);
+ vsnprintf(buffer, len, fmt, args);
+ va_end(args);
+
+ kunit_err(current->kunit_test, "%s:%d: %s", file, line, buffer);
+ kunit_kfree(current->kunit_test, buffer);
+}
+EXPORT_SYMBOL_GPL(__kunit_fail_current_test);
+
/*
* Append formatted message to log, size of which is limited to
* KUNIT_LOG_SIZE bytes (including null terminating byte).
@@ -273,9 +306,7 @@ static void kunit_try_run_case(void *data)
struct kunit_suite *suite = ctx->suite;
struct kunit_case *test_case = ctx->test_case;

-#if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
current->kunit_test = test;
-#endif /* IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT) */

/*
* kunit_run_case_internal may encounter a fatal error; if it does,
@@ -624,9 +655,7 @@ void kunit_cleanup(struct kunit *test)
spin_unlock(&test->lock);
kunit_remove_resource(test, res);
}
-#if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
current->kunit_test = NULL;
-#endif /* IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT)*/
}
EXPORT_SYMBOL_GPL(kunit_cleanup);

--
2.30.0.478.g8a0d178c01-goog
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