kunit: Use string_stream for test log

Replace the fixed-size log buffer with a string_stream so that the
log can grow as lines are added.

The existing kunit log tests have been updated for using a
string_stream as the log. No new test have been added because there
are already tests for the underlying string_stream.

As the log tests now depend on string_stream functions they cannot
build when kunit-test is a module. They have been surrounded by
a #if to replace them with skipping version when the test is
build as a module. Though this isn't pretty, it avoids moving
code to another file while that code is also being changed.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

3 files changed, 75 insertions, 61 deletions

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/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/test.c b/lib/kunit/test.c
index bd1ef86fcd71..651cbda9f250 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);
 
@@ -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';
 }