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>

1 files changed, 7 insertions, 5 deletions

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);