Merge tag 'linux_kselftest-kunit-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kunit updates from Shuah Khan:

 - string-stream testing enhancements

 - several fixes memory leaks

 - fix to reset status during parameter handling

* tag 'linux_kselftest-kunit-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: test: Fix the possible memory leak in executor_test
  kunit: Fix possible memory leak in kunit_filter_suites()
  kunit: Fix the wrong kfree of copy for kunit_filter_suites()
  kunit: Fix missed memory release in kunit_free_suite_set()
  kunit: Reset test status on each param iteration
  kunit: string-stream: Test performance of string_stream
  kunit: Use string_stream for test log
  kunit: string-stream: Add tests for freeing resource-managed string_stream
  kunit: string-stream: Decouple string_stream from kunit
  kunit: string-stream: Add kunit_alloc_string_stream()
  kunit: Don't use a managed alloc in is_literal()
  kunit: string-stream-test: Add cases for string_stream newline appending
  kunit: string-stream: Add option to make all lines end with newline
  kunit: string-stream: Improve testing of string_stream
  kunit: string-stream: Don't create a fragment for empty strings

10 files changed, 728 insertions, 139 deletions

diff --git a/lib/kunit/assert.c b/lib/kunit/assert.c
index 05a09652f5a1..dd1d633d0fe2 100644
--- a/lib/kunit/assert.c
+++ b/lib/kunit/assert.c
@@ -89,8 +89,7 @@ void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
 EXPORT_SYMBOL_GPL(kunit_ptr_not_err_assert_format);
 
 /* Checks if `text` is a literal representing `value`, e.g. "5" and 5 */
-static bool is_literal(struct kunit *test, const char *text, long long value,
-		       gfp_t gfp)
+static bool is_literal(const char *text, long long value)
 {
 	char *buffer;
 	int len;
@@ -100,14 +99,15 @@ static bool is_literal(struct kunit *test, const char *text, long long value,
 	if (strlen(text) != len)
 		return false;
 
-	buffer = kunit_kmalloc(test, len+1, gfp);
+	buffer = kmalloc(len+1, GFP_KERNEL);
 	if (!buffer)
 		return false;
 
 	snprintf(buffer, len+1, "%lld", value);
 	ret = strncmp(buffer, text, len) == 0;
 
-	kunit_kfree(test, buffer);
+	kfree(buffer);
+
 	return ret;
 }
 
@@ -125,14 +125,12 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
 			  binary_assert->text->left_text,
 			  binary_assert->text->operation,
 			  binary_assert->text->right_text);
-	if (!is_literal(stream->test, binary_assert->text->left_text,
-			binary_assert->left_value, stream->gfp))
+	if (!is_literal(binary_assert->text->left_text, binary_assert->left_value))
 		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)\n",
 				  binary_assert->text->left_text,
 				  binary_assert->left_value,
 				  binary_assert->left_value);
-	if (!is_literal(stream->test, binary_assert->text->right_text,
-			binary_assert->right_value, stream->gfp))
+	if (!is_literal(binary_assert->text->right_text, binary_assert->right_value))
 		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)",
 				  binary_assert->text->right_text,
 				  binary_assert->right_value,
diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c
index 22c5c496a68f..270d185737e6 100644
--- a/lib/kunit/debugfs.c
+++ b/lib/kunit/debugfs.c
@@ -37,14 +37,21 @@ void kunit_debugfs_init(void)
 		debugfs_rootdir = debugfs_create_dir(KUNIT_DEBUGFS_ROOT, NULL);
 }
 
-static void debugfs_print_result(struct seq_file *seq,
-				 struct kunit_suite *suite,
-				 struct kunit_case *test_case)
+static void debugfs_print_result(struct seq_file *seq, struct string_stream *log)
 {
-	if (!test_case || !test_case->log)
+	struct string_stream_fragment *frag_container;
+
+	if (!log)
 		return;
 
-	seq_printf(seq, "%s", test_case->log);
+	/*
+	 * Walk the fragments so we don't need to allocate a temporary
+	 * buffer to hold the entire string.
+	 */
+	spin_lock(&log->lock);
+	list_for_each_entry(frag_container, &log->fragments, node)
+		seq_printf(seq, "%s", frag_container->fragment);
+	spin_unlock(&log->lock);
 }
 
 /*
@@ -69,10 +76,9 @@ static int debugfs_print_results(struct seq_file *seq, void *v)
 	seq_printf(seq, KUNIT_SUBTEST_INDENT "1..%zd\n", kunit_suite_num_test_cases(suite));
 
 	kunit_suite_for_each_test_case(suite, test_case)
-		debugfs_print_result(seq, suite, test_case);
+		debugfs_print_result(seq, test_case->log);
 
-	if (suite->log)
-		seq_printf(seq, "%s", suite->log);
+	debugfs_print_result(seq, suite->log);
 
 	seq_printf(seq, "%s %d %s\n",
 		   kunit_status_to_ok_not_ok(success), 1, suite->name);
@@ -105,9 +111,13 @@ void kunit_debugfs_create_suite(struct kunit_suite *suite)
 	struct kunit_case *test_case;
 
 	/* Allocate logs before creating debugfs representation. */
-	suite->log = kzalloc(KUNIT_LOG_SIZE, GFP_KERNEL);
-	kunit_suite_for_each_test_case(suite, test_case)
-		test_case->log = kzalloc(KUNIT_LOG_SIZE, GFP_KERNEL);
+	suite->log = alloc_string_stream(GFP_KERNEL);
+	string_stream_set_append_newlines(suite->log, true);
+
+	kunit_suite_for_each_test_case(suite, test_case) {
+		test_case->log = alloc_string_stream(GFP_KERNEL);
+		string_stream_set_append_newlines(test_case->log, true);
+	}
 
 	suite->debugfs = debugfs_create_dir(suite->name, debugfs_rootdir);
 
@@ -121,7 +131,7 @@ void kunit_debugfs_destroy_suite(struct kunit_suite *suite)
 	struct kunit_case *test_case;
 
 	debugfs_remove_recursive(suite->debugfs);
-	kfree(suite->log);
+	string_stream_destroy(suite->log);
 	kunit_suite_for_each_test_case(suite, test_case)
-		kfree(test_case->log);
+		string_stream_destroy(test_case->log);
 }
diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
index a6348489d45f..1236b3cd2fbb 100644
--- a/lib/kunit/executor.c
+++ b/lib/kunit/executor.c
@@ -137,8 +137,10 @@ void kunit_free_suite_set(struct kunit_suite_set suite_set)
 {
 	struct kunit_suite * const *suites;
 
-	for (suites = suite_set.start; suites < suite_set.end; suites++)
+	for (suites = suite_set.start; suites < suite_set.end; suites++) {
+		kfree((*suites)->test_cases);
 		kfree(*suites);
+	}
 	kfree(suite_set.start);
 }
 
@@ -155,10 +157,11 @@ kunit_filter_suites(const struct kunit_suite_set *suite_set,
 	struct kunit_suite_set filtered = {NULL, NULL};
 	struct kunit_glob_filter parsed_glob;
 	struct kunit_attr_filter *parsed_filters = NULL;
+	struct kunit_suite * const *suites;
 
 	const size_t max = suite_set->end - suite_set->start;
 
-	copy = kmalloc_array(max, sizeof(*filtered.start), GFP_KERNEL);
+	copy = kcalloc(max, sizeof(*filtered.start), GFP_KERNEL);
 	if (!copy) { /* won't be able to run anything, return an empty set */
 		return filtered;
 	}
@@ -193,7 +196,7 @@ kunit_filter_suites(const struct kunit_suite_set *suite_set,
 					parsed_glob.test_glob);
 			if (IS_ERR(filtered_suite)) {
 				*err = PTR_ERR(filtered_suite);
-				goto free_parsed_filters;
+				goto free_filtered_suite;
 			}
 		}
 		if (filter_count > 0 && parsed_filters != NULL) {
@@ -210,11 +213,11 @@ kunit_filter_suites(const struct kunit_suite_set *suite_set,
 				filtered_suite = new_filtered_suite;
 
 				if (*err)
-					goto free_parsed_filters;
+					goto free_filtered_suite;
 
 				if (IS_ERR(filtered_suite)) {
 					*err = PTR_ERR(filtered_suite);
-					goto free_parsed_filters;
+					goto free_filtered_suite;
 				}
 				if (!filtered_suite)
 					break;
@@ -229,6 +232,14 @@ kunit_filter_suites(const struct kunit_suite_set *suite_set,
 	filtered.start = copy_start;
 	filtered.end = copy;
 
+free_filtered_suite:
+	if (*err) {
+		for (suites = copy_start; suites < copy; suites++) {
+			kfree((*suites)->test_cases);
+			kfree(*suites);
+		}
+	}
+
 free_parsed_filters:
 	if (filter_count)
 		kfree(parsed_filters);
@@ -241,7 +252,7 @@ free_parsed_glob:
 
 free_copy:
 	if (*err)
-		kfree(copy);
+		kfree(copy_start);
 
 	return filtered;
 }
diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
index b4f6f96b2844..22d4ee86dbed 100644
--- a/lib/kunit/executor_test.c
+++ b/lib/kunit/executor_test.c
@@ -9,7 +9,7 @@
 #include <kunit/test.h>
 #include <kunit/attributes.h>
 
-static void kfree_at_end(struct kunit *test, const void *to_free);
+static void free_suite_set_at_end(struct kunit *test, const void *to_free);
 static struct kunit_suite *alloc_fake_suite(struct kunit *test,
 					    const char *suite_name,
 					    struct kunit_case *test_cases);
@@ -56,7 +56,7 @@ static void filter_suites_test(struct kunit *test)
 	got = kunit_filter_suites(&suite_set, "suite2", NULL, NULL, &err);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start);
+	free_suite_set_at_end(test, &got);
 
 	/* Validate we just have suite2 */
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start[0]);
@@ -82,7 +82,7 @@ static void filter_suites_test_glob_test(struct kunit *test)
 	got = kunit_filter_suites(&suite_set, "suite2.test2", NULL, NULL, &err);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start);
+	free_suite_set_at_end(test, &got);
 
 	/* Validate we just have suite2 */
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start[0]);
@@ -109,7 +109,7 @@ static void filter_suites_to_empty_test(struct kunit *test)
 
 	got = kunit_filter_suites(&suite_set, "not_found", NULL, NULL, &err);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start); /* just in case */
+	free_suite_set_at_end(test, &got); /* just in case */
 
 	KUNIT_EXPECT_PTR_EQ_MSG(test, got.start, got.end,
 				"should be empty to indicate no match");
@@ -172,7 +172,7 @@ static void filter_attr_test(struct kunit *test)
 	got = kunit_filter_suites(&suite_set, NULL, filter, NULL, &err);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start);
+	free_suite_set_at_end(test, &got);
 
 	/* Validate we just have normal_suite */
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start[0]);
@@ -200,7 +200,7 @@ static void filter_attr_empty_test(struct kunit *test)
 
 	got = kunit_filter_suites(&suite_set, NULL, filter, NULL, &err);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start); /* just in case */
+	free_suite_set_at_end(test, &got); /* just in case */
 
 	KUNIT_EXPECT_PTR_EQ_MSG(test, got.start, got.end,
 				"should be empty to indicate no match");
@@ -222,7 +222,7 @@ static void filter_attr_skip_test(struct kunit *test)
 	got = kunit_filter_suites(&suite_set, NULL, filter, "skip", &err);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
 	KUNIT_ASSERT_EQ(test, err, 0);
-	kfree_at_end(test, got.start);
+	free_suite_set_at_end(test, &got);
 
 	/* Validate we have both the slow and normal test */
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start[0]->test_cases);
@@ -256,18 +256,26 @@ kunit_test_suites(&executor_test_suite);
 
 /* Test helpers */
 
-/* Use the resource API to register a call to kfree(to_free).
+static void free_suite_set(void *suite_set)
+{
+	kunit_free_suite_set(*(struct kunit_suite_set *)suite_set);
+	kfree(suite_set);
+}
+
+/* Use the resource API to register a call to free_suite_set.
  * Since we never actually use the resource, it's safe to use on const data.
  */
-static void kfree_at_end(struct kunit *test, const void *to_free)
+static void free_suite_set_at_end(struct kunit *test, const void *to_free)
 {
-	/* kfree() handles NULL already, but avoid allocating a no-op cleanup. */
-	if (IS_ERR_OR_NULL(to_free))
+	struct kunit_suite_set *free;
+
+	if (!((struct kunit_suite_set *)to_free)->start)
 		return;
 
-	kunit_add_action(test,
-			(kunit_action_t *)kfree,
-			(void *)to_free);
+	free = kzalloc(sizeof(struct kunit_suite_set), GFP_KERNEL);
+	*free = *(struct kunit_suite_set *)to_free;
+
+	kunit_add_action(test, free_suite_set, (void *)free);
 }
 
 static struct kunit_suite *alloc_fake_suite(struct kunit *test,
diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c
index 01a769f35e1d..6bb5c2ef6696 100644
--- a/lib/kunit/kunit-example-test.c
+++ b/lib/kunit/kunit-example-test.c
@@ -190,6 +190,7 @@ static void example_static_stub_test(struct kunit *test)
 static const struct example_param {
 	int value;
 } example_params_array[] = {
+	{ .value = 3, },
 	{ .value = 2, },
 	{ .value = 1, },
 	{ .value = 0, },
@@ -213,8 +214,8 @@ static void example_params_test(struct kunit *test)
 	KUNIT_ASSERT_NOT_NULL(test, param);
 
 	/* Test can be skipped on unsupported param values */
-	if (!param->value)
-		kunit_skip(test, "unsupported param value");
+	if (!is_power_of_2(param->value))
+		kunit_skip(test, "unsupported param value %d", param->value);
 
 	/* You can use param values for parameterized testing */
 	KUNIT_EXPECT_EQ(test, param->value % param->value, 0);
diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
index 83d8e90ca7a2..99d2a3a528e1 100644
--- a/lib/kunit/kunit-test.c
+++ b/lib/kunit/kunit-test.c
@@ -8,6 +8,7 @@
 #include <kunit/test.h>
 #include <kunit/test-bug.h>
 
+#include "string-stream.h"
 #include "try-catch-impl.h"
 
 struct kunit_try_catch_test_context {
@@ -530,12 +531,27 @@ static struct kunit_suite kunit_resource_test_suite = {
 	.test_cases = kunit_resource_test_cases,
 };
 
+/*
+ * Log tests call string_stream functions, which aren't exported. So only
+ * build this code if this test is built-in.
+ */
+#if IS_BUILTIN(CONFIG_KUNIT_TEST)
+
+/* This avoids a cast warning if kfree() is passed direct to kunit_add_action(). */
+static void kfree_wrapper(void *p)
+{
+	kfree(p);
+}
+
 static void kunit_log_test(struct kunit *test)
 {
 	struct kunit_suite suite;
-
-	suite.log = kunit_kzalloc(test, KUNIT_LOG_SIZE, GFP_KERNEL);
+#ifdef CONFIG_KUNIT_DEBUGFS
+	char *full_log;
+#endif
+	suite.log = kunit_alloc_string_stream(test, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, suite.log);
+	string_stream_set_append_newlines(suite.log, true);
 
 	kunit_log(KERN_INFO, test, "put this in log.");
 	kunit_log(KERN_INFO, test, "this too.");
@@ -543,14 +559,21 @@ static void kunit_log_test(struct kunit *test)
 	kunit_log(KERN_INFO, &suite, "along with this.");
 
 #ifdef CONFIG_KUNIT_DEBUGFS
+	KUNIT_EXPECT_TRUE(test, test->log->append_newlines);
+
+	full_log = string_stream_get_string(test->log);
+	kunit_add_action(test, (kunit_action_t *)kfree, full_log);
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
-				     strstr(test->log, "put this in log."));
+				     strstr(full_log, "put this in log."));
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
-				     strstr(test->log, "this too."));
+				     strstr(full_log, "this too."));
+
+	full_log = string_stream_get_string(suite.log);
+	kunit_add_action(test, kfree_wrapper, full_log);
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
-				     strstr(suite.log, "add to suite log."));
+				     strstr(full_log, "add to suite log."));
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
-				     strstr(suite.log, "along with this."));
+				     strstr(full_log, "along with this."));
 #else
 	KUNIT_EXPECT_NULL(test, test->log);
 #endif
@@ -558,15 +581,30 @@ static void kunit_log_test(struct kunit *test)
 
 static void kunit_log_newline_test(struct kunit *test)
 {
+	char *full_log;
+
 	kunit_info(test, "Add newline\n");
 	if (test->log) {
-		KUNIT_ASSERT_NOT_NULL_MSG(test, strstr(test->log, "Add newline\n"),
-			"Missing log line, full log:\n%s", test->log);
-		KUNIT_EXPECT_NULL(test, strstr(test->log, "Add newline\n\n"));
+		full_log = string_stream_get_string(test->log);
+		kunit_add_action(test, kfree_wrapper, full_log);
+		KUNIT_ASSERT_NOT_NULL_MSG(test, strstr(full_log, "Add newline\n"),
+			"Missing log line, full log:\n%s", full_log);
+		KUNIT_EXPECT_NULL(test, strstr(full_log, "Add newline\n\n"));
 	} else {
 		kunit_skip(test, "only useful when debugfs is enabled");
 	}
 }
+#else
+static void kunit_log_test(struct kunit *test)
+{
+	kunit_skip(test, "Log tests only run when built-in");
+}
+
+static void kunit_log_newline_test(struct kunit *test)
+{
+	kunit_skip(test, "Log tests only run when built-in");
+}
+#endif /* IS_BUILTIN(CONFIG_KUNIT_TEST) */
 
 static struct kunit_case kunit_log_test_cases[] = {
 	KUNIT_CASE(kunit_log_test),
diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c
index 110f3a993250..06822766f29a 100644
--- a/lib/kunit/string-stream-test.c
+++ b/lib/kunit/string-stream-test.c
@@ -6,48 +6,539 @@
  * Author: Brendan Higgins <brendanhiggins@google.com>
  */
 
+#include <kunit/static_stub.h>
 #include <kunit/test.h>
+#include <linux/ktime.h>
 #include <linux/slab.h>
+#include <linux/timekeeping.h>
 
 #include "string-stream.h"
 
-static void string_stream_test_empty_on_creation(struct kunit *test)
+struct string_stream_test_priv {
+	/* For testing resource-managed free. */
+	struct string_stream *expected_free_stream;
+	bool stream_was_freed;
+	bool stream_free_again;
+};
+
+/* Avoids a cast warning if kfree() is passed direct to kunit_add_action(). */
+static void kfree_wrapper(void *p)
+{
+	kfree(p);
+}
+
+/* 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);
+}
+
+static char *get_concatenated_string(struct kunit *test, struct string_stream *stream)
+{
+	char *str = string_stream_get_string(stream);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, str);
+	kunit_add_action(test, kfree_wrapper, (void *)str);
+
+	return str;
+}
+
+/* Managed string_stream object is initialized correctly. */
+static void string_stream_managed_init_test(struct kunit *test)
+{
+	struct string_stream *stream;
+
+	/* Resource-managed initialization. */
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	KUNIT_EXPECT_EQ(test, stream->length, 0);
+	KUNIT_EXPECT_TRUE(test, list_empty(&stream->fragments));
+	KUNIT_EXPECT_TRUE(test, (stream->gfp == GFP_KERNEL));
+	KUNIT_EXPECT_FALSE(test, stream->append_newlines);
+	KUNIT_EXPECT_TRUE(test, string_stream_is_empty(stream));
+}
+
+/* Unmanaged string_stream object is initialized correctly. */
+static void string_stream_unmanaged_init_test(struct kunit *test)
+{
+	struct string_stream *stream;
+
+	stream = alloc_string_stream(GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+	kunit_add_action(test, cleanup_raw_stream, stream);
+
+	KUNIT_EXPECT_EQ(test, stream->length, 0);
+	KUNIT_EXPECT_TRUE(test, list_empty(&stream->fragments));
+	KUNIT_EXPECT_EQ(test, stream->gfp, GFP_KERNEL);
+	KUNIT_EXPECT_FALSE(test, stream->append_newlines);
+
+	KUNIT_EXPECT_TRUE(test, string_stream_is_empty(stream));
+}
+
+static void string_stream_destroy_stub(struct string_stream *stream)
+{
+	struct kunit *fake_test = kunit_get_current_test();
+	struct string_stream_test_priv *priv = fake_test->priv;
+
+	/* The kunit could own string_streams other than the one we are testing. */
+	if (stream == priv->expected_free_stream) {
+		if (priv->stream_was_freed)
+			priv->stream_free_again = true;
+		else
+			priv->stream_was_freed = true;
+	}
+
+	/*
+	 * Calling string_stream_destroy() will only call this function again
+	 * because the redirection stub is still active.
+	 * Avoid calling deactivate_static_stub() or changing current->kunit_test
+	 * during cleanup.
+	 */
+	string_stream_clear(stream);
+	kfree(stream);
+}
+
+/* kunit_free_string_stream() calls string_stream_desrtoy() */
+static void string_stream_managed_free_test(struct kunit *test)
+{
+	struct string_stream_test_priv *priv = test->priv;
+
+	priv->expected_free_stream = NULL;
+	priv->stream_was_freed = false;
+	priv->stream_free_again = false;
+
+	kunit_activate_static_stub(test,
+				   string_stream_destroy,
+				   string_stream_destroy_stub);
+
+	priv->expected_free_stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->expected_free_stream);
+
+	/* This should call the stub function. */
+	kunit_free_string_stream(test, priv->expected_free_stream);
+
+	KUNIT_EXPECT_TRUE(test, priv->stream_was_freed);
+	KUNIT_EXPECT_FALSE(test, priv->stream_free_again);
+}
+
+/* string_stream object is freed when test is cleaned up. */
+static void string_stream_resource_free_test(struct kunit *test)
+{
+	struct string_stream_test_priv *priv = test->priv;
+	struct kunit *fake_test;
+
+	fake_test = kunit_kzalloc(test, sizeof(*fake_test), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fake_test);
+
+	kunit_init_test(fake_test, "string_stream_fake_test", NULL);
+	fake_test->priv = priv;
+
+	/*
+	 * Activate stub before creating string_stream so the
+	 * string_stream will be cleaned up first.
+	 */
+	priv->expected_free_stream = NULL;
+	priv->stream_was_freed = false;
+	priv->stream_free_again = false;
+
+	kunit_activate_static_stub(fake_test,
+				   string_stream_destroy,
+				   string_stream_destroy_stub);
+
+	priv->expected_free_stream = kunit_alloc_string_stream(fake_test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->expected_free_stream);
+
+	/* Set current->kunit_test to fake_test so the static stub will be called. */
+	current->kunit_test = fake_test;
+
+	/* Cleanup test - the stub function should be called */
+	kunit_cleanup(fake_test);
+
+	/* Set current->kunit_test back to current test. */
+	current->kunit_test = test;
+
+	KUNIT_EXPECT_TRUE(test, priv->stream_was_freed);
+	KUNIT_EXPECT_FALSE(test, priv->stream_free_again);
+}
+
+/*
+ * Add a series of lines to a string_stream. Check that all lines
+ * appear in the correct order and no characters are dropped.
+ */
+static void string_stream_line_add_test(struct kunit *test)
+{
+	struct string_stream *stream;
+	char line[60];
+	char *concat_string, *pos, *string_end;
+	size_t len, total_len;
+	int num_lines, i;
+
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	/* Add series of sequence numbered lines */
+	total_len = 0;
+	for (i = 0; i < 100; ++i) {
+		len = snprintf(line, sizeof(line),
+			"The quick brown fox jumps over the lazy penguin %d\n", i);
+
+		/* Sanity-check that our test string isn't truncated */
+		KUNIT_ASSERT_LT(test, len, sizeof(line));
+
+		string_stream_add(stream, line);
+		total_len += len;
+	}
+	num_lines = i;
+
+	concat_string = get_concatenated_string(test, stream);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, concat_string);
+	KUNIT_EXPECT_EQ(test, strlen(concat_string), total_len);
+
+	/*
+	 * Split the concatenated string at the newlines and check that
+	 * all the original added strings are present.
+	 */
+	pos = concat_string;
+	for (i = 0; i < num_lines; ++i) {
+		string_end = strchr(pos, '\n');
+		KUNIT_EXPECT_NOT_NULL(test, string_end);
+
+		/* Convert to NULL-terminated string */
+		*string_end = '\0';
+
+		snprintf(line, sizeof(line),
+			 "The quick brown fox jumps over the lazy penguin %d", i);
+		KUNIT_EXPECT_STREQ(test, pos, line);
+
+		pos = string_end + 1;
+	}
+
+	/* There shouldn't be any more data after this */
+	KUNIT_EXPECT_EQ(test, strlen(pos), 0);
+}
+
+/* Add a series of lines of variable length to a string_stream. */
+static void string_stream_variable_length_line_test(struct kunit *test)
+{
+	static const char line[] =
+		"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+		" 0123456789!$%^&*()_-+={}[]:;@'~#<>,.?/|";
+	struct string_stream *stream;
+	struct rnd_state rnd;
+	char *concat_string, *pos, *string_end;
+	size_t offset, total_len;
+	int num_lines, i;
+
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	/*
+	 * Log many lines of varying lengths until we have created
+	 * many fragments.
+	 * The "randomness" must be repeatable.
+	 */
+	prandom_seed_state(&rnd, 3141592653589793238ULL);
+	total_len = 0;
+	for (i = 0; i < 100; ++i) {
+		offset = prandom_u32_state(&rnd) % (sizeof(line) - 1);
+		string_stream_add(stream, "%s\n", &line[offset]);
+		total_len += sizeof(line) - offset;
+	}
+	num_lines = i;
+
+	concat_string = get_concatenated_string(test, stream);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, concat_string);
+	KUNIT_EXPECT_EQ(test, strlen(concat_string), total_len);
+
+	/*
+	 * Split the concatenated string at the newlines and check that
+	 * all the original added strings are present.
+	 */
+	prandom_seed_state(&rnd, 3141592653589793238ULL);
+	pos = concat_string;
+	for (i = 0; i < num_lines; ++i) {
+		string_end = strchr(pos, '\n');
+		KUNIT_EXPECT_NOT_NULL(test, string_end);
+
+		/* Convert to NULL-terminated string */
+		*string_end = '\0';
+
+		offset = prandom_u32_state(&rnd) % (sizeof(line) - 1);
+		KUNIT_EXPECT_STREQ(test, pos, &line[offset]);
+
+		pos = string_end + 1;
+	}
+
+	/* There shouldn't be any more data after this */
+	KUNIT_EXPECT_EQ(test, strlen(pos), 0);
+}
+
+/* Appending the content of one string stream to another. */
+static void string_stream_append_test(struct kunit *test)
+{
+	static const char * const strings_1[] = {
+		"one", "two", "three", "four", "five", "six",
+		"seven", "eight", "nine", "ten",
+	};
+	static const char * const strings_2[] = {
+		"Apple", "Pear", "Orange", "Banana", "Grape", "Apricot",
+	};
+	struct string_stream *stream_1, *stream_2;
+	const char *stream1_content_before_append, *stream_2_content;
+	char *combined_content;
+	size_t combined_length;
+	int i;
+
+	stream_1 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_1);
+
+	stream_2 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_2);
+
+	/* Append content of empty stream to empty stream */
+	string_stream_append(stream_1, stream_2);
+	KUNIT_EXPECT_EQ(test, strlen(get_concatenated_string(test, stream_1)), 0);
+
+	/* Add some data to stream_1 */
+	for (i = 0; i < ARRAY_SIZE(strings_1); ++i)
+		string_stream_add(stream_1, "%s\n", strings_1[i]);
+
+	stream1_content_before_append = get_concatenated_string(test, stream_1);
+
+	/* Append content of empty stream to non-empty stream */
+	string_stream_append(stream_1, stream_2);
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream_1),
+			   stream1_content_before_append);
+
+	/* Add some data to stream_2 */
+	for (i = 0; i < ARRAY_SIZE(strings_2); ++i)
+		string_stream_add(stream_2, "%s\n", strings_2[i]);
+
+	/* Append content of non-empty stream to non-empty stream */
+	string_stream_append(stream_1, stream_2);
+
+	/*
+	 * End result should be the original content of stream_1 plus
+	 * the content of stream_2.
+	 */
+	stream_2_content = get_concatenated_string(test, stream_2);
+	combined_length = strlen(stream1_content_before_append) + strlen(stream_2_content);
+	combined_length++; /* for terminating \0 */
+	combined_content = kunit_kmalloc(test, combined_length, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, combined_content);
+	snprintf(combined_content, combined_length, "%s%s",
+		 stream1_content_before_append, stream_2_content);
+
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream_1), combined_content);
+
+	/* Append content of non-empty stream to empty stream */
+	kunit_free_string_stream(test, stream_1);
+
+	stream_1 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_1);
+
+	string_stream_append(stream_1, stream_2);
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream_1), stream_2_content);
+}
+
+/* Appending the content of one string stream to one with auto-newlining. */
+static void string_stream_append_auto_newline_test(struct kunit *test)
+{
+	struct string_stream *stream_1, *stream_2;
+
+	/* Stream 1 has newline appending enabled */
+	stream_1 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_1);
+	string_stream_set_append_newlines(stream_1, true);
+	KUNIT_EXPECT_TRUE(test, stream_1->append_newlines);
+
+	/* Stream 2 does not append newlines */
+	stream_2 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_2);
+
+	/* Appending a stream with a newline should not add another newline */
+	string_stream_add(stream_1, "Original string\n");
+	string_stream_add(stream_2, "Appended content\n");
+	string_stream_add(stream_2, "More stuff\n");
+	string_stream_append(stream_1, stream_2);
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream_1),
+			   "Original string\nAppended content\nMore stuff\n");
+
+	kunit_free_string_stream(test, stream_2);
+	stream_2 = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream_2);
+
+	/*
+	 * Appending a stream without newline should add a final newline.
+	 * The appended string_stream is treated as a single string so newlines
+	 * should not be inserted between fragments.
+	 */
+	string_stream_add(stream_2, "Another");
+	string_stream_add(stream_2, "And again");
+	string_stream_append(stream_1, stream_2);
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream_1),
+			   "Original string\nAppended content\nMore stuff\nAnotherAnd again\n");
+}
+
+/* Adding an empty string should not create a fragment. */
+static void string_stream_append_empty_string_test(struct kunit *test)
 {
-	struct string_stream *stream = alloc_string_stream(test, GFP_KERNEL);
+	struct string_stream *stream;
+	int original_frag_count;
+
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
 
+	/* Formatted empty string */
+	string_stream_add(stream, "%s", "");
 	KUNIT_EXPECT_TRUE(test, string_stream_is_empty(stream));
+	KUNIT_EXPECT_TRUE(test, list_empty(&stream->fragments));
+
+	/* Adding an empty string to a non-empty stream */
+	string_stream_add(stream, "Add this line");
+	original_frag_count = list_count_nodes(&stream->fragments);
+
+	string_stream_add(stream, "%s", "");
+	KUNIT_EXPECT_EQ(test, list_count_nodes(&stream->fragments), original_frag_count);
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream), "Add this line");
 }
 
-static void string_stream_test_not_empty_after_add(struct kunit *test)
+/* Adding strings without automatic newline appending */
+static void string_stream_no_auto_newline_test(struct kunit *test)
 {
-	struct string_stream *stream = alloc_string_stream(test, GFP_KERNEL);
+	struct string_stream *stream;
 
-	string_stream_add(stream, "Foo");
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
 
-	KUNIT_EXPECT_FALSE(test, string_stream_is_empty(stream));
+	/*
+	 * Add some strings with and without newlines. All formatted newlines
+	 * should be preserved. It should not add any extra newlines.
+	 */
+	string_stream_add(stream, "One");
+	string_stream_add(stream, "Two\n");
+	string_stream_add(stream, "%s\n", "Three");
+	string_stream_add(stream, "%s", "Four\n");
+	string_stream_add(stream, "Five\n%s", "Six");
+	string_stream_add(stream, "Seven\n\n");
+	string_stream_add(stream, "Eight");
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream),
+			   "OneTwo\nThree\nFour\nFive\nSixSeven\n\nEight");
 }
 
-static void string_stream_test_get_string(struct kunit *test)
+/* Adding strings with automatic newline appending */
+static void string_stream_auto_newline_test(struct kunit *test)
 {
-	struct string_stream *stream = alloc_string_stream(test, GFP_KERNEL);
-	char *output;
+	struct string_stream *stream;
+
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	string_stream_set_append_newlines(stream, true);
+	KUNIT_EXPECT_TRUE(test, stream->append_newlines);
+
+	/*
+	 * Add some strings with and without newlines. Newlines should
+	 * be appended to lines that do not end with \n, but newlines
+	 * resulting from the formatting should not be changed.
+	 */
+	string_stream_add(stream, "One");
+	string_stream_add(stream, "Two\n");
+	string_stream_add(stream, "%s\n", "Three");
+	string_stream_add(stream, "%s", "Four\n");
+	string_stream_add(stream, "Five\n%s", "Six");
+	string_stream_add(stream, "Seven\n\n");
+	string_stream_add(stream, "Eight");
+	KUNIT_EXPECT_STREQ(test, get_concatenated_string(test, stream),
+			   "One\nTwo\nThree\nFour\nFive\nSix\nSeven\n\nEight\n");
+}
+
+/*
+ * This doesn't actually "test" anything. It reports time taken
+ * and memory used for logging a large number of lines.
+ */
+static void string_stream_performance_test(struct kunit *test)
+{
+	struct string_stream_fragment *frag_container;
+	struct string_stream *stream;
+	char test_line[101];
+	ktime_t start_time, end_time;
+	size_t len, bytes_requested, actual_bytes_used, total_string_length;
+	int offset, i;
+
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+	memset(test_line, 'x', sizeof(test_line) - 1);
+	test_line[sizeof(test_line) - 1] = '\0';
+
+	start_time = ktime_get();
+	for (i = 0; i < 10000; i++) {
+		offset = i % (sizeof(test_line) - 1);
+		string_stream_add(stream, "%s: %d\n", &test_line[offset], i);
+	}
+	end_time = ktime_get();
+
+	/*
+	 * Calculate memory used. This doesn't include invisible
+	 * overhead due to kernel allocator fragment size rounding.
+	 */
+	bytes_requested = sizeof(*stream);
+	actual_bytes_used = ksize(stream);
+	total_string_length = 0;
+
+	list_for_each_entry(frag_container, &stream->fragments, node) {
+		bytes_requested += sizeof(*frag_container);
+		actual_bytes_used += ksize(frag_container);
+
+		len = strlen(frag_container->fragment);
+		total_string_length += len;
+		bytes_requested += len + 1; /* +1 for '\0' */
+		actual_bytes_used += ksize(frag_container->fragment);
+	}
+
+	kunit_info(test, "Time elapsed:           %lld us\n",
+		   ktime_us_delta(end_time, start_time));
+	kunit_info(test, "Total string length:    %zu\n", total_string_length);
+	kunit_info(test, "Bytes requested:        %zu\n", bytes_requested);
+	kunit_info(test, "Actual bytes allocated: %zu\n", actual_bytes_used);
+}
+
+static int string_stream_test_init(struct kunit *test)
+{
+	struct string_stream_test_priv *priv;
+
+	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
 
-	string_stream_add(stream, "Foo");
-	string_stream_add(stream, " %s", "bar");
+	test->priv = priv;
 
-	output = string_stream_get_string(stream);
-	KUNIT_ASSERT_STREQ(test, output, "Foo bar");
+	return 0;
 }
 
 static struct kunit_case string_stream_test_cases[] = {
-	KUNIT_CASE(string_stream_test_empty_on_creation),
-	KUNIT_CASE(string_stream_test_not_empty_after_add),
-	KUNIT_CASE(string_stream_test_get_string),
+	KUNIT_CASE(string_stream_managed_init_test),
+	KUNIT_CASE(string_stream_unmanaged_init_test),
+	KUNIT_CASE(string_stream_managed_free_test),
+	KUNIT_CASE(string_stream_resource_free_test),
+	KUNIT_CASE(string_stream_line_add_test),
+	KUNIT_CASE(string_stream_variable_length_line_test),
+	KUNIT_CASE(string_stream_append_test),
+	KUNIT_CASE(string_stream_append_auto_newline_test),
+	KUNIT_CASE(string_stream_append_empty_string_test),
+	KUNIT_CASE(string_stream_no_auto_newline_test),
+	KUNIT_CASE(string_stream_auto_newline_test),
+	KUNIT_CASE(string_stream_performance_test),
 	{}
 };
 
 static struct kunit_suite string_stream_test_suite = {
 	.name = "string-stream-test",
-	.test_cases = string_stream_test_cases
+	.test_cases = string_stream_test_cases,
+	.init = string_stream_test_init,
 };
 kunit_test_suites(&string_stream_test_suite);
diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
index cc32743c1171..a6f3616c2048 100644
--- a/lib/kunit/string-stream.c
+++ b/lib/kunit/string-stream.c
@@ -6,6 +6,7 @@
  * Author: Brendan Higgins <brendanhiggins@google.com>
  */
 
+#include <kunit/static_stub.h>
 #include <kunit/test.h>
 #include <linux/list.h>
 #include <linux/slab.h>
@@ -13,30 +14,28 @@
 #include "string-stream.h"
 
 
-static struct string_stream_fragment *alloc_string_stream_fragment(
-		struct kunit *test, int len, gfp_t gfp)
+static struct string_stream_fragment *alloc_string_stream_fragment(int len, gfp_t gfp)
 {
 	struct string_stream_fragment *frag;
 
-	frag = kunit_kzalloc(test, sizeof(*frag), gfp);
+	frag = kzalloc(sizeof(*frag), gfp);
 	if (!frag)
 		return ERR_PTR(-ENOMEM);
 
-	frag->fragment = kunit_kmalloc(test, len, gfp);
+	frag->fragment = kmalloc(len, gfp);
 	if (!frag->fragment) {
-		kunit_kfree(test, frag);
+		kfree(frag);
 		return ERR_PTR(-ENOMEM);
 	}
 
 	return frag;
 }
 
-static void string_stream_fragment_destroy(struct kunit *test,
-					   struct string_stream_fragment *frag)
+static void string_stream_fragment_destroy(struct string_stream_fragment *frag)
 {
 	list_del(&frag->node);
-	kunit_kfree(test, frag->fragment);
-	kunit_kfree(test, frag);
+	kfree(frag->fragment);
+	kfree(frag);
 }
 
 int string_stream_vadd(struct string_stream *stream,
@@ -44,26 +43,44 @@ int string_stream_vadd(struct string_stream *stream,
 		       va_list args)
 {
 	struct string_stream_fragment *frag_container;
-	int len;
+	int buf_len, result_len;
 	va_list args_for_counting;
 
 	/* Make a copy because `vsnprintf` could change it */
 	va_copy(args_for_counting, args);
 
-	/* Need space for null byte. */
-	len = vsnprintf(NULL, 0, fmt, args_for_counting) + 1;
+	/* Evaluate length of formatted string */
+	buf_len = vsnprintf(NULL, 0, fmt, args_for_counting);
 
 	va_end(args_for_counting);
 
-	frag_container = alloc_string_stream_fragment(stream->test,
-						      len,
-						      stream->gfp);
+	if (buf_len == 0)
+		return 0;
+
+	/* Reserve one extra for possible appended newline. */
+	if (stream->append_newlines)
+		buf_len++;
+
+	/* Need space for null byte. */
+	buf_len++;
+
+	frag_container = alloc_string_stream_fragment(buf_len, stream->gfp);
 	if (IS_ERR(frag_container))
 		return PTR_ERR(frag_container);
 
-	len = vsnprintf(frag_container->fragment, len, fmt, args);
+	if (stream->append_newlines) {
+		/* Don't include reserved newline byte in writeable length. */
+		result_len = vsnprintf(frag_container->fragment, buf_len - 1, fmt, args);
+
+		/* Append newline if necessary. */
+		if (frag_container->fragment[result_len - 1] != '\n')
+			result_len = strlcat(frag_container->fragment, "\n", buf_len);
+	} else {
+		result_len = vsnprintf(frag_container->fragment, buf_len, fmt, args);
+	}
+
 	spin_lock(&stream->lock);
-	stream->length += len;
+	stream->length += result_len;
 	list_add_tail(&frag_container->node, &stream->fragments);
 	spin_unlock(&stream->lock);
 
@@ -82,7 +99,7 @@ int string_stream_add(struct string_stream *stream, const char *fmt, ...)
 	return result;
 }
 
-static void string_stream_clear(struct string_stream *stream)
+void string_stream_clear(struct string_stream *stream)
 {
 	struct string_stream_fragment *frag_container, *frag_container_safe;
 
@@ -91,7 +108,7 @@ static void string_stream_clear(struct string_stream *stream)
 				 frag_container_safe,
 				 &stream->fragments,
 				 node) {
-		string_stream_fragment_destroy(stream->test, frag_container);
+		string_stream_fragment_destroy(frag_container);
 	}
 	stream->length = 0;
 	spin_unlock(&stream->lock);
@@ -103,7 +120,7 @@ char *string_stream_get_string(struct string_stream *stream)
 	size_t buf_len = stream->length + 1; /* +1 for null byte. */
 	char *buf;
 
-	buf = kunit_kzalloc(stream->test, buf_len, stream->gfp);
+	buf = kzalloc(buf_len, stream->gfp);
 	if (!buf)
 		return NULL;
 
@@ -119,13 +136,17 @@ int string_stream_append(struct string_stream *stream,
 			 struct string_stream *other)
 {
 	const char *other_content;
+	int ret;
 
 	other_content = string_stream_get_string(other);
 
 	if (!other_content)
 		return -ENOMEM;
 
-	return string_stream_add(stream, other_content);
+	ret = string_stream_add(stream, other_content);
+	kfree(other_content);
+
+	return ret;
 }
 
 bool string_stream_is_empty(struct string_stream *stream)
@@ -133,16 +154,15 @@ bool string_stream_is_empty(struct string_stream *stream)
 	return list_empty(&stream->fragments);
 }
 
-struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
+struct string_stream *alloc_string_stream(gfp_t gfp)
 {
 	struct string_stream *stream;
 
-	stream = kunit_kzalloc(test, sizeof(*stream), gfp);
+	stream = kzalloc(sizeof(*stream), gfp);
 	if (!stream)
 		return ERR_PTR(-ENOMEM);
 
 	stream->gfp = gfp;
-	stream->test = test;
 	INIT_LIST_HEAD(&stream->fragments);
 	spin_lock_init(&stream->lock);
 
@@ -151,5 +171,37 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
 
 void string_stream_destroy(struct string_stream *stream)
 {
+	KUNIT_STATIC_STUB_REDIRECT(string_stream_destroy, stream);
+
+	if (!stream)
+		return;
+
 	string_stream_clear(stream);
+	kfree(stream);
+}
+
+static void resource_free_string_stream(void *p)
+{
+	struct string_stream *stream = p;
+
+	string_stream_destroy(stream);
+}
+
+struct string_stream *kunit_alloc_string_stream(struct kunit *test, gfp_t gfp)
+{
+	struct string_stream *stream;
+
+	stream = alloc_string_stream(gfp);
+	if (IS_ERR(stream))
+		return stream;
+
+	if (kunit_add_action_or_reset(test, resource_free_string_stream, stream) != 0)
+		return ERR_PTR(-ENOMEM);
+
+	return stream;
+}
+
+void kunit_free_string_stream(struct kunit *test, struct string_stream *stream)
+{
+	kunit_release_action(test, resource_free_string_stream, (void *)stream);
 }
diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
index b669f9a75a94..7be2450c7079 100644
--- a/lib/kunit/string-stream.h
+++ b/lib/kunit/string-stream.h
@@ -23,13 +23,17 @@ struct string_stream {
 	struct list_head fragments;
 	/* length and fragments are protected by this lock */
 	spinlock_t lock;
-	struct kunit *test;
 	gfp_t gfp;
+	bool append_newlines;
 };
 
 struct kunit;
 
-struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp);
+struct string_stream *kunit_alloc_string_stream(struct kunit *test, gfp_t gfp);
+void kunit_free_string_stream(struct kunit *test, struct string_stream *stream);
+
+struct string_stream *alloc_string_stream(gfp_t gfp);
+void free_string_stream(struct string_stream *stream);
 
 int __printf(2, 3) string_stream_add(struct string_stream *stream,
 				     const char *fmt, ...);
@@ -38,6 +42,8 @@ int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
 				      const char *fmt,
 				      va_list args);
 
+void string_stream_clear(struct string_stream *stream);
+
 char *string_stream_get_string(struct string_stream *stream);
 
 int string_stream_append(struct string_stream *stream,
@@ -47,4 +53,10 @@ bool string_stream_is_empty(struct string_stream *stream);
 
 void string_stream_destroy(struct string_stream *stream);
 
+static inline void string_stream_set_append_newlines(struct string_stream *stream,
+						     bool append_newlines)
+{
+	stream->append_newlines = append_newlines;
+}
+
 #endif /* _KUNIT_STRING_STREAM_H */
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 421f13981412..f2eb71f1a66c 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -109,51 +109,17 @@ static void kunit_print_test_stats(struct kunit *test,
 		  stats.total);
 }
 
-/**
- * kunit_log_newline() - Add newline to the end of log if one is not
- * already present.
- * @log: The log to add the newline to.
- */
-static void kunit_log_newline(char *log)
-{
-	int log_len, len_left;
-
-	log_len = strlen(log);
-	len_left = KUNIT_LOG_SIZE - log_len - 1;
-
-	if (log_len > 0 && log[log_len - 1] != '\n')
-		strncat(log, "\n", len_left);
-}
-
-/*
- * Append formatted message to log, size of which is limited to
- * KUNIT_LOG_SIZE bytes (including null terminating byte).
- */
-void kunit_log_append(char *log, const char *fmt, ...)
+/* Append formatted message to log. */
+void kunit_log_append(struct string_stream *log, const char *fmt, ...)
 {
 	va_list args;
-	int len, log_len, len_left;
 
 	if (!log)
 		return;
 
-	log_len = strlen(log);
-	len_left = KUNIT_LOG_SIZE - log_len - 1;
-	if (len_left <= 0)
-		return;
-
-	/* Evaluate length of line to add to log */
 	va_start(args, fmt);
-	len = vsnprintf(NULL, 0, fmt, args) + 1;
+	string_stream_vadd(log, fmt, args);
 	va_end(args);
-
-	/* Print formatted line to the log */
-	va_start(args, fmt);
-	vsnprintf(log + log_len, min(len, len_left), fmt, args);
-	va_end(args);
-
-	/* Add newline to end of log if not already present. */
-	kunit_log_newline(log);
 }
 EXPORT_SYMBOL_GPL(kunit_log_append);
 
@@ -296,7 +262,7 @@ static void kunit_print_string_stream(struct kunit *test,
 		kunit_err(test, "\n");
 	} else {
 		kunit_err(test, "%s", buf);
-		kunit_kfree(test, buf);
+		kfree(buf);
 	}
 }
 
@@ -308,7 +274,7 @@ static void kunit_fail(struct kunit *test, const struct kunit_loc *loc,
 
 	kunit_set_failure(test);
 
-	stream = alloc_string_stream(test, GFP_KERNEL);
+	stream = kunit_alloc_string_stream(test, GFP_KERNEL);
 	if (IS_ERR(stream)) {
 		WARN(true,
 		     "Could not allocate stream to print failed assertion in %s:%d\n",
@@ -322,7 +288,7 @@ static void kunit_fail(struct kunit *test, const struct kunit_loc *loc,
 
 	kunit_print_string_stream(test, stream);
 
-	string_stream_destroy(stream);
+	kunit_free_string_stream(test, stream);
 }
 
 void __noreturn __kunit_abort(struct kunit *test)
@@ -359,14 +325,14 @@ void __kunit_do_failed_assertion(struct kunit *test,
 }
 EXPORT_SYMBOL_GPL(__kunit_do_failed_assertion);
 
-void kunit_init_test(struct kunit *test, const char *name, char *log)
+void kunit_init_test(struct kunit *test, const char *name, struct string_stream *log)
 {
 	spin_lock_init(&test->lock);
 	INIT_LIST_HEAD(&test->resources);
 	test->name = name;
 	test->log = log;
 	if (test->log)
-		test->log[0] = '\0';
+		string_stream_clear(log);
 	test->status = KUNIT_SUCCESS;
 	test->status_comment[0] = '\0';
 }
@@ -648,12 +614,14 @@ int kunit_run_tests(struct kunit_suite *suite)
 						      param_desc,
 						      test.status_comment);
 
+				kunit_update_stats(&param_stats, test.status);
+
 				/* Get next param. */
 				param_desc[0] = '\0';
 				test.param_value = test_case->generate_params(test.param_value, param_desc);
 				test.param_index++;
-
-				kunit_update_stats(&param_stats, test.status);
+				test.status = KUNIT_SUCCESS;
+				test.status_comment[0] = '\0';
 			}
 		}