On Tue, Jan 11, 2022 at 2:42 PM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote:
>
> This is per Linus's suggestion in [1].
>
> The issue there is that every KUNIT_EXPECT/KUNIT_ASSERT puts a
> kunit_assert object onto the stack. Normally we rely on compilers to
> elide this, but when that doesn't work out, this blows up the stack
> usage of kunit test functions.
>
> We can move some data off the stack by making it static.
> This change introduces a new `struct kunit_loc` to hold the file and
> line number and then just passing assert_type (EXPECT or ASSERT) as an
> argument.
>
> In [1], it was suggested to also move out the format string as well, but
> users could theoretically craft a format string at runtime, so we can't.
>
> This change leaves a copy of `assert_type` in kunit_assert for now
> because cleaning up all the macros to not pass it around is a bit more
> involved.
>
> Here's an example of the expanded code for KUNIT_FAIL():
> if (__builtin_expect(!!(!(false)), 0)) {
> static const struct kunit_loc loc = { .file = ... };
> struct kunit_fail_assert __assertion = { .assert = { .type ... };
> kunit_do_failed_assertion(test, &loc, KUNIT_EXPECTATION, &__assertion.assert, ...);
> };
>
> [1] https://groups.google.com/g/kunit-dev/c/i3fZXgvBrfA/m/VULQg1z6BAAJ
>
> Signed-off-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: David Gow <davidgow@xxxxxxxxxx>
One question below, but other than that,
Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
> ---
> include/kunit/assert.h | 25 ++++++++++++++++---------
> include/kunit/test.h | 12 +++++++++++-
> lib/kunit/assert.c | 9 +++++----
> lib/kunit/test.c | 15 +++++++++------
> 4 files changed, 41 insertions(+), 20 deletions(-)
>
> diff --git a/include/kunit/assert.h b/include/kunit/assert.h
> index 3da6c792496c..4f91dbdb886a 100644
> --- a/include/kunit/assert.h
> +++ b/include/kunit/assert.h
> @@ -28,11 +28,21 @@ enum kunit_assert_type {
> KUNIT_EXPECTATION,
> };
>
> +/**
> + * struct kunit_loc - Identifies the source location of a line of code.
> + * @line: the line number in the file.
> + * @file: the file name.
> + */
> +struct kunit_loc {
> + int line;
> + const char *file;
> +};
> +
> +#define KUNIT_CURRENT_LOC { .file = __FILE__, .line = __LINE__ }
> +
> /**
> * struct kunit_assert - Data for printing a failed assertion or expectation.
> * @type: the type (either an expectation or an assertion) of this kunit_assert.
> - * @line: the source code line number that the expectation/assertion is at.
> - * @file: the file path of the source file that the expectation/assertion is in.
> * @message: an optional message to provide additional context.
> * @format: a function which formats the data in this kunit_assert to a string.
> *
> @@ -40,9 +50,7 @@ enum kunit_assert_type {
> * format a string to a user reporting the failure.
> */
> struct kunit_assert {
> - enum kunit_assert_type type;
> - int line;
> - const char *file;
> + enum kunit_assert_type type; // TODO(dlatypov@xxxxxxxxxx): delete this
Can you provide some context for this?
> struct va_format message;
> void (*format)(const struct kunit_assert *assert,
> struct string_stream *stream);
> @@ -65,14 +73,13 @@ struct kunit_assert {
> */
> #define KUNIT_INIT_ASSERT_STRUCT(assert_type, fmt) { \
> .type = assert_type, \
> - .file = __FILE__, \
> - .line = __LINE__, \
> .message = KUNIT_INIT_VA_FMT_NULL, \
> .format = fmt \
> }
>
> -void kunit_base_assert_format(const struct kunit_assert *assert,
> - struct string_stream *stream);
> +void kunit_assert_prologue(const struct kunit_loc *loc,
> + enum kunit_assert_type type,
> + struct string_stream *stream);
>
> void kunit_assert_print_msg(const struct kunit_assert *assert,
> struct string_stream *stream);
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 25ea3bce6663..7b752175e614 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
