Merge tag 'linux_kselftest-kunit-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kunit updates from Shuah Khan:

 - fix race condition in try-catch completion

 - change __kunit_test_suites_init() to exit early if there is
   nothing to test

 - change string-stream-test to use KUNIT_DEFINE_ACTION_WRAPPER

 - move fault tests behind KUNIT_FAULT_TEST Kconfig option

 - kthread test fixes and improvements

 - iov_iter test fixes

* tag 'linux_kselftest-kunit-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: bail out early in __kunit_test_suites_init() if there are no suites to test
  kunit: string-stream-test: use KUNIT_DEFINE_ACTION_WRAPPER
  kunit: test: Move fault tests behind KUNIT_FAULT_TEST Kconfig option
  kunit: unregister the device on error
  kunit: Fix race condition in try-catch completion
  kunit: Add tests for fault
  kunit: Print last test location on fault
  kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests
  kunit: Handle test faults
  kunit: Fix timeout message
  kunit: Fix kthread reference
  kunit: Handle thread creation error

Author: torvalds

include/kunit/test.h

@@ -301,6 +301,8 @@ struct kunit {
 	struct list_head resources; /* Protected by lock. */
 
 	char status_comment[KUNIT_STATUS_COMMENT_SIZE];
+	/* Saves the last seen test. Useful to help with faults. */
+	struct kunit_loc last_seen;
 };
 
 static inline void kunit_set_failure(struct kunit *test)
@@ -567,6 +569,15 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
 #define kunit_err(test, fmt, ...) \
 	kunit_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
 
+/*
+ * Must be called at the beginning of each KUNIT_*_ASSERTION().
+ * Cf. KUNIT_CURRENT_LOC.
+ */
+#define _KUNIT_SAVE_LOC(test) do {					       \
+	WRITE_ONCE(test->last_seen.file, __FILE__);			       \
+	WRITE_ONCE(test->last_seen.line, __LINE__);			       \
+} while (0)
+
 /**
  * KUNIT_SUCCEED() - A no-op expectation. Only exists for code clarity.
  * @test: The test context object.
@@ -575,7 +586,7 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
  * words, it does nothing and only exists for code clarity. See
  * KUNIT_EXPECT_TRUE() for more information.
  */
-#define KUNIT_SUCCEED(test) do {} while (0)
+#define KUNIT_SUCCEED(test) _KUNIT_SAVE_LOC(test)
 
 void __noreturn __kunit_abort(struct kunit *test);
 
@@ -601,14 +612,16 @@ void __printf(6, 7) __kunit_do_failed_assertion(struct kunit *test,
 } while (0)
 
 
-#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...)		       \
+#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...) do {		       \
+	_KUNIT_SAVE_LOC(test);						       \
 	_KUNIT_FAILED(test,						       \
 		      assert_type,					       \
 		      kunit_fail_assert,				       \
 		      kunit_fail_assert_format,				       \
 		      {},						       \
 		      fmt,						       \
-		      ##__VA_ARGS__)
+		      ##__VA_ARGS__);					       \
+} while (0)
 
 /**
  * KUNIT_FAIL() - Always causes a test to fail when evaluated.
@@ -637,6 +650,7 @@ void __printf(6, 7) __kunit_do_failed_assertion(struct kunit *test,
 			      fmt,					       \
 			      ...)					       \
 do {									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(!!(condition_) == !!expected_true_))			       \
 		break;							       \
 									       \
@@ -698,6 +712,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(__left op __right))					       \
 		break;							       \
 									       \
@@ -758,6 +773,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely((__left) && (__right) && (strcmp(__left, __right) op 0)))   \
 		break;							       \
 									       \
@@ -791,6 +807,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(__left && __right))					       \
 		if (likely(memcmp(__left, __right, __size) op 0))	       \
 			break;						       \
@@ -815,6 +832,7 @@ do {									       \
 do {									       \
 	const typeof(ptr) __ptr = (ptr);				       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (!IS_ERR_OR_NULL(__ptr))					       \
 		break;							       \
 									       \

include/kunit/try-catch.h

@@ -14,13 +14,11 @@
 
 typedef void (*kunit_try_catch_func_t)(void *);
 
-struct completion;
 struct kunit;
 
 /**
  * struct kunit_try_catch - provides a generic way to run code which might fail.
  * @test: The test case that is currently being executed.
- * @try_completion: Completion that the control thread waits on while test runs.
  * @try_result: Contains any errno obtained while running test case.
  * @try: The function, the test case, to attempt to run.
  * @catch: The function called if @try bails out.
@@ -46,7 +44,6 @@ struct kunit;
 struct kunit_try_catch {
 	/* private: internal use only. */
 	struct kunit *test;
-	struct completion *try_completion;
 	int try_result;
 	kunit_try_catch_func_t try;
 	kunit_try_catch_func_t catch;

kernel/kthread.c

@@ -315,6 +315,7 @@ void __noreturn kthread_exit(long result)
 	kthread->result = result;
 	do_exit(0);
 }
+EXPORT_SYMBOL(kthread_exit);
 
 /**
  * kthread_complete_and_exit - Exit the current kthread.

lib/kunit/Kconfig

@@ -24,6 +24,17 @@ config KUNIT_DEBUGFS
 	  test suite, which allow users to see results of the last test suite
 	  run that occurred.
 
+config KUNIT_FAULT_TEST
+	bool "Enable KUnit tests which print BUG stacktraces"
+	depends on KUNIT_TEST
+	depends on !UML
+	default y
+	help
+	  Enables fault handling tests for the KUnit framework. These tests may
+	  trigger a kernel BUG(), and the associated stack trace, even when they
+	  pass. If this conflicts with your test infrastrcture (or is confusing
+	  or annoying), they can be disabled by setting this to N.
+
 config KUNIT_TEST
 	tristate "KUnit test for KUnit" if !KUNIT_ALL_TESTS
 	default KUNIT_ALL_TESTS

lib/kunit/device.c

@@ -51,7 +51,7 @@ int kunit_bus_init(void)
 
 	error = bus_register(&kunit_bus_type);
 	if (error)
-		bus_unregister(&kunit_bus_type);
+		root_device_unregister(kunit_bus_device);
 	return error;
 }
 

lib/kunit/kunit-test.c

@@ -109,6 +109,48 @@ static struct kunit_suite kunit_try_catch_test_suite = {
 	.test_cases = kunit_try_catch_test_cases,
 };
 
+#if IS_ENABLED(CONFIG_KUNIT_FAULT_TEST)
+
+static void kunit_test_null_dereference(void *data)
+{
+	struct kunit *test = data;
+	int *null = NULL;
+
+	*null = 0;
+
+	KUNIT_FAIL(test, "This line should never be reached\n");
+}
+
+static void kunit_test_fault_null_dereference(struct kunit *test)
+{
+	struct kunit_try_catch_test_context *ctx = test->priv;
+	struct kunit_try_catch *try_catch = ctx->try_catch;
+
+	kunit_try_catch_init(try_catch,
+			     test,
+			     kunit_test_null_dereference,
+			     kunit_test_catch);
+	kunit_try_catch_run(try_catch, test);
+
+	KUNIT_EXPECT_EQ(test, try_catch->try_result, -EINTR);
+	KUNIT_EXPECT_TRUE(test, ctx->function_called);
+}
+
+#endif /* CONFIG_KUNIT_FAULT_TEST */
+
+static struct kunit_case kunit_fault_test_cases[] = {
+#if IS_ENABLED(CONFIG_KUNIT_FAULT_TEST)
+	KUNIT_CASE(kunit_test_fault_null_dereference),
+#endif /* CONFIG_KUNIT_FAULT_TEST */
+	{}
+};
+
+static struct kunit_suite kunit_fault_test_suite = {
+	.name = "kunit_fault",
+	.init = kunit_try_catch_test_init,
+	.test_cases = kunit_fault_test_cases,
+};
+
 /*
  * Context for testing test managed resources
  * is_resource_initialized is used to test arbitrary resources
@@ -826,6 +868,7 @@ static struct kunit_suite kunit_current_test_suite = {
 
 kunit_test_suites(&kunit_try_catch_test_suite, &kunit_resource_test_suite,
 		  &kunit_log_test_suite, &kunit_status_test_suite,
-		  &kunit_current_test_suite, &kunit_device_test_suite);
+		  &kunit_current_test_suite, &kunit_device_test_suite,
+		  &kunit_fault_test_suite);
 
 MODULE_LICENSE("GPL v2");

lib/kunit/string-stream-test.c

@@ -22,18 +22,10 @@ struct string_stream_test_priv {
 };
 
 /* Avoids a cast warning if kfree() is passed direct to kunit_add_action(). */
-static void kfree_wrapper(void *p)
-{
-	kfree(p);
-}
+KUNIT_DEFINE_ACTION_WRAPPER(kfree_wrapper, kfree, const void *);
 
 /* Avoids a cast warning if string_stream_destroy() is passed direct to kunit_add_action(). */
-static void cleanup_raw_stream(void *p)
-{
-	struct string_stream *stream = p;
-
-	string_stream_destroy(stream);
-}
+KUNIT_DEFINE_ACTION_WRAPPER(cleanup_raw_stream, string_stream_destroy, struct string_stream *);
 
 static char *get_concatenated_string(struct kunit *test, struct string_stream *stream)
 {

lib/kunit/test.c

@@ -712,6 +712,9 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
 {
 	unsigned int i;
 
+	if (num_suites == 0)
+		return 0;
+
 	if (!kunit_enabled() && num_suites > 0) {
 		pr_info("kunit: disabled\n");
 		return 0;

lib/kunit/try-catch.c

@@ -11,23 +11,27 @@
 #include <linux/completion.h>
 #include <linux/kernel.h>
 #include <linux/kthread.h>
+#include <linux/sched/task.h>
 
 #include "try-catch-impl.h"
 
 void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
 {
 	try_catch->try_result = -EFAULT;
-	kthread_complete_and_exit(try_catch->try_completion, -EFAULT);
+	kthread_exit(0);
 }
 EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
 
 static int kunit_generic_run_threadfn_adapter(void *data)
 {
 	struct kunit_try_catch *try_catch = data;
 
+	try_catch->try_result = -EINTR;
 	try_catch->try(try_catch->context);
+	if (try_catch->try_result == -EINTR)
+		try_catch->try_result = 0;
 
-	kthread_complete_and_exit(try_catch->try_completion, 0);
+	return 0;
 }
 
 static unsigned long kunit_test_timeout(void)
@@ -57,39 +61,53 @@ static unsigned long kunit_test_timeout(void)
 
 void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 {
-	DECLARE_COMPLETION_ONSTACK(try_completion);
 	struct kunit *test = try_catch->test;
 	struct task_struct *task_struct;
+	struct completion *task_done;
 	int exit_code, time_remaining;
 
 	try_catch->context = context;
-	try_catch->try_completion = &try_completion;
 	try_catch->try_result = 0;
-	task_struct = kthread_run(kunit_generic_run_threadfn_adapter,
-				  try_catch,
-				  "kunit_try_catch_thread");
+	task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
+				     try_catch, "kunit_try_catch_thread");
 	if (IS_ERR(task_struct)) {
+		try_catch->try_result = PTR_ERR(task_struct);
 		try_catch->catch(try_catch->context);
 		return;
 	}
+	get_task_struct(task_struct);
+	/*
+	 * As for a vfork(2), task_struct->vfork_done (pointing to the
+	 * underlying kthread->exited) can be used to wait for the end of a
+	 * kernel thread. It is set to NULL when the thread exits, so we
+	 * keep a copy here.
+	 */
+	task_done = task_struct->vfork_done;
+	wake_up_process(task_struct);
 
-	time_remaining = wait_for_completion_timeout(&try_completion,
+	time_remaining = wait_for_completion_timeout(task_done,
 						     kunit_test_timeout());
 	if (time_remaining == 0) {
-		kunit_err(test, "try timed out\n");
 		try_catch->try_result = -ETIMEDOUT;
 		kthread_stop(task_struct);
 	}
 
+	put_task_struct(task_struct);
 	exit_code = try_catch->try_result;
 
 	if (!exit_code)
 		return;
 
 	if (exit_code == -EFAULT)
 		try_catch->try_result = 0;
-	else if (exit_code == -EINTR)
-		kunit_err(test, "wake_up_process() was never called\n");
+	else if (exit_code == -EINTR) {
+		if (test->last_seen.file)
+			kunit_err(test, "try faulted: last line seen %s:%d\n",
+				  test->last_seen.file, test->last_seen.line);
+		else
+			kunit_err(test, "try faulted\n");
+	} else if (exit_code == -ETIMEDOUT)
+		kunit_err(test, "try timed out\n");
 	else if (exit_code)
 		kunit_err(test, "Unknown error: %d\n", exit_code);