kunit: remove va_format from kunit_assert

The concern is that having a lot of redundant fields in kunit_assert can
blow up stack usage if the compiler doesn't optimize them away [1].

The comment on this field implies that it was meant to be initialized
when the expect/assert was declared, but this only happens when we run
kunit_do_failed_assertion().

We don't need to access it outside of that function, so move it out of
the struct and make it a local variable there.

This change also takes the chance to reduce the number of macros by
inlining the now simplified KUNIT_INIT_ASSERT_STRUCT() macro.

[1] https://groups.google.com/g/kunit-dev/c/i3fZXgvBrfA/m/VULQg1z6BAAJ

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

2 files changed, 23 insertions, 16 deletions

diff --git a/lib/kunit/assert.c b/lib/kunit/assert.c
index 9f4492a8e24e..c9c7ee0dfafa 100644
--- a/lib/kunit/assert.c
+++ b/lib/kunit/assert.c
@@ -30,22 +30,23 @@ void kunit_assert_prologue(const struct kunit_loc *loc,
 }
 EXPORT_SYMBOL_GPL(kunit_assert_prologue);
 
-void kunit_assert_print_msg(const struct kunit_assert *assert,
-			    struct string_stream *stream)
+static void kunit_assert_print_msg(const struct va_format *message,
+				   struct string_stream *stream)
 {
-	if (assert->message.fmt)
-		string_stream_add(stream, "\n%pV", &assert->message);
+	if (message->fmt)
+		string_stream_add(stream, "\n%pV", message);
 }
-EXPORT_SYMBOL_GPL(kunit_assert_print_msg);
 
 void kunit_fail_assert_format(const struct kunit_assert *assert,
+			      const struct va_format *message,
 			      struct string_stream *stream)
 {
-	string_stream_add(stream, "%pV", &assert->message);
+	string_stream_add(stream, "%pV", message);
 }
 EXPORT_SYMBOL_GPL(kunit_fail_assert_format);
 
 void kunit_unary_assert_format(const struct kunit_assert *assert,
+			       const struct va_format *message,
 			       struct string_stream *stream)
 {
 	struct kunit_unary_assert *unary_assert;
@@ -60,11 +61,12 @@ void kunit_unary_assert_format(const struct kunit_assert *assert,
 		string_stream_add(stream,
 				  KUNIT_SUBTEST_INDENT "Expected %s to be false, but is true\n",
 				  unary_assert->condition);
-	kunit_assert_print_msg(assert, stream);
+	kunit_assert_print_msg(message, stream);
 }
 EXPORT_SYMBOL_GPL(kunit_unary_assert_format);
 
 void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
+				     const struct va_format *message,
 				     struct string_stream *stream)
 {
 	struct kunit_ptr_not_err_assert *ptr_assert;
@@ -82,7 +84,7 @@ void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
 				  ptr_assert->text,
 				  PTR_ERR(ptr_assert->value));
 	}
-	kunit_assert_print_msg(assert, stream);
+	kunit_assert_print_msg(message, stream);
 }
 EXPORT_SYMBOL_GPL(kunit_ptr_not_err_assert_format);
 
@@ -110,6 +112,7 @@ static bool is_literal(struct kunit *test, const char *text, long long value,
 }
 
 void kunit_binary_assert_format(const struct kunit_assert *assert,
+				const struct va_format *message,
 				struct string_stream *stream)
 {
 	struct kunit_binary_assert *binary_assert;
@@ -132,11 +135,12 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
 		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld",
 				  binary_assert->right_text,
 				  binary_assert->right_value);
-	kunit_assert_print_msg(assert, stream);
+	kunit_assert_print_msg(message, stream);
 }
 EXPORT_SYMBOL_GPL(kunit_binary_assert_format);
 
 void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
+				    const struct va_format *message,
 				    struct string_stream *stream)
 {
 	struct kunit_binary_ptr_assert *binary_assert;
@@ -155,7 +159,7 @@ void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
 	string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %px",
 			  binary_assert->right_text,
 			  binary_assert->right_value);
-	kunit_assert_print_msg(assert, stream);
+	kunit_assert_print_msg(message, stream);
 }
 EXPORT_SYMBOL_GPL(kunit_binary_ptr_assert_format);
 
@@ -176,6 +180,7 @@ static bool is_str_literal(const char *text, const char *value)
 }
 
 void kunit_binary_str_assert_format(const struct kunit_assert *assert,
+				    const struct va_format *message,
 				    struct string_stream *stream)
 {
 	struct kunit_binary_str_assert *binary_assert;
@@ -196,6 +201,6 @@ void kunit_binary_str_assert_format(const struct kunit_assert *assert,
 		string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == \"%s\"",
 				  binary_assert->right_text,
 				  binary_assert->right_value);
-	kunit_assert_print_msg(assert, stream);
+	kunit_assert_print_msg(message, stream);
 }
 EXPORT_SYMBOL_GPL(kunit_binary_str_assert_format);
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 7dec3248562f..3bca3bf5c15b 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -241,7 +241,8 @@ static void kunit_print_string_stream(struct kunit *test,
 }
 
 static void kunit_fail(struct kunit *test, const struct kunit_loc *loc,
-		       enum kunit_assert_type type, struct kunit_assert *assert)
+		       enum kunit_assert_type type, struct kunit_assert *assert,
+		       const struct va_format *message)
 {
 	struct string_stream *stream;
 
@@ -257,7 +258,7 @@ static void kunit_fail(struct kunit *test, const struct kunit_loc *loc,
 	}
 
 	kunit_assert_prologue(loc, type, stream);
-	assert->format(assert, stream);
+	assert->format(assert, message, stream);
 
 	kunit_print_string_stream(test, stream);
 
@@ -284,12 +285,13 @@ void kunit_do_failed_assertion(struct kunit *test,
 			       const char *fmt, ...)
 {
 	va_list args;
+	struct va_format message;
 	va_start(args, fmt);
 
-	assert->message.fmt = fmt;
-	assert->message.va = &args;
+	message.fmt = fmt;
+	message.va = &args;
 
-	kunit_fail(test, loc, type, assert);
+	kunit_fail(test, loc, type, assert, &message);
 
 	va_end(args);