[PATCH v5 08/10] kunit: string-stream: Add tests for freeing resource-managed string_stream

[Richard Fitzgerald]

string_stream_managed_free_test() allocates a resource-managed
string_stream and tests that kunit_free_string_stream() calls
string_stream_destroy().

string_stream_resource_free_test() allocates a resource-managed
string_stream and tests that string_stream_destroy() is called
when the test resources are cleaned up.

The old string_stream_init_test() has been split into two tests,
one for kunit_alloc_string_stream() and the other for
alloc_string_stream().

Signed-off-by: Richard Fitzgerald <r...@opensource.cirrus.com>
---
Changes since V4:
- Added test case for kunit_free_string_stream().
- Split the initialization test into separate tests for managed and
unmanaged allocations.
---
lib/kunit/string-stream-test.c | 135 ++++++++++++++++++++++++++++++++-
lib/kunit/string-stream.c | 3 +
2 files changed, 134 insertions(+), 4 deletions(-)

diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c
index 45a2d221f1b5..6897c57e0db7 100644
--- a/lib/kunit/string-stream-test.c
+++ b/lib/kunit/string-stream-test.c
@@ -6,11 +6,25 @@
* Author: Brendan Higgins <brendan...@google.com>
*/

+#include <kunit/static_stub.h>
#include <kunit/test.h>
#include <linux/slab.h>

#include "string-stream.h"

+struct string_stream_test_priv {
+ /* For testing resource-managed free. */
+ struct string_stream *freed_stream;
+ bool stream_free_again;
+};
+
+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);
@@ -21,11 +35,12 @@ static char *get_concatenated_string(struct kunit *test, struct string_stream *s
return str;
}

-/* string_stream object is initialized correctly. */
-static void string_stream_init_test(struct kunit *test)
+/* 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);

@@ -37,6 +52,101 @@ static void string_stream_init_test(struct kunit *test)
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;
+
+ if (priv->freed_stream)
+ priv->stream_free_again = true;
+
+ priv->freed_stream = stream;
+
+ /*
+ * Avoid calling deactivate_static_stub() or changing
+ * current->kunit_test during cleanup. Leave the stream to
+ * be freed during the test exit.
+ */
+}
+
+/* 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;
+ struct string_stream *stream;
+
+ priv->freed_stream = NULL;
+ priv->stream_free_again = false;
+ kunit_activate_static_stub(test,
+ string_stream_destroy,
+ string_stream_destroy_stub);
+
+ stream = kunit_alloc_string_stream(test, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
+
+ /* This should call the stub function. */
+ kunit_free_string_stream(test, stream);
+
+ KUNIT_EXPECT_PTR_EQ(test, priv->freed_stream, stream);
+ 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;
+ struct string_stream *stream;
+
+ 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->freed_stream = NULL;
+ priv->stream_free_again = false;
+ kunit_activate_static_stub(fake_test,
+ string_stream_destroy,
+ string_stream_destroy_stub);
+
+ stream = kunit_alloc_string_stream(fake_test, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, 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_PTR_EQ(test, priv->freed_stream, stream);
+ 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.
@@ -327,8 +437,24 @@ static void string_stream_auto_newline_test(struct kunit *test)
"One\nTwo\nThree\nFour\nFive\nSix\nSeven\n\nEight\n");
}

+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;
+
+ test->priv = priv;
+
+ return 0;
+}
+
static struct kunit_case string_stream_test_cases[] = {
- KUNIT_CASE(string_stream_init_test),
+ 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),
@@ -341,6 +467,7 @@ static struct kunit_case string_stream_test_cases[] = {

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 c39f1cba3bcd..d2ded5207e9e 100644
--- a/lib/kunit/string-stream.c
+++ b/lib/kunit/string-stream.c
@@ -6,6 +6,7 @@
* Author: Brendan Higgins <brendan...@google.com>
*/

+#include <kunit/static_stub.h>
#include <kunit/test.h>
#include <linux/list.h>
#include <linux/slab.h>
@@ -170,6 +171,8 @@ struct string_stream *alloc_string_stream(gfp_t gfp)

void string_stream_destroy(struct string_stream *stream)
{
+ KUNIT_STATIC_STUB_REDIRECT(string_stream_destroy, stream);
+
if (!stream)
return;

--
2.30.2

[David Gow]

On Thu, 24 Aug 2023 at 22:32, 'Richard Fitzgerald' via KUnit
Development <kuni...@googlegroups.com> wrote:
>
> string_stream_managed_free_test() allocates a resource-managed
> string_stream and tests that kunit_free_string_stream() calls
> string_stream_destroy().
>
> string_stream_resource_free_test() allocates a resource-managed
> string_stream and tests that string_stream_destroy() is called
> when the test resources are cleaned up.
>
> The old string_stream_init_test() has been split into two tests,
> one for kunit_alloc_string_stream() and the other for
> alloc_string_stream().
>
> Signed-off-by: Richard Fitzgerald <r...@opensource.cirrus.com>
> ---
> Changes since V4:
> - Added test case for kunit_free_string_stream().
> - Split the initialization test into separate tests for managed and
> unmanaged allocations.
> ---

Looking over this again, I'm not convinced the streams are actually
getting freed. Once the stub has finished, the stream is removed from
the list of deferred actions / resources.

I'll have another look tomorrow in case I missed anything, but if so,
this might need to be explained further / made more obvious.

-- David

Is this worth having here? It's only used once, and it could easily be
replaced with a manual call to string_stream_destroy() at the end of
the function.

If it were likely that list_empty() or string_stream_is_empty() would
crash, it would be more worthwhile to make sure the cleanup happens
anyway, but as-is, I think it's safe enough either way.

Are we ever actually freeing this during test exit? I don't think so.

I think you'd need to either free 'stream' here, or free it (either
manually or with a deferred action) at the end of every test which
uses this stub.

That being said, I'd agree it's best to avoid manually calling
deactivate_static_stub() and/or changin current->kunit_test during
cleanup. While it should actually be safe, as far as I can tell, it'd
be very confusing.

> +}
> +
> +/* 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;
> + struct string_stream *stream;
> +
> + priv->freed_stream = NULL;
> + priv->stream_free_again = false;
> + kunit_activate_static_stub(test,
> + string_stream_destroy,
> + string_stream_destroy_stub);
> +
> + stream = kunit_alloc_string_stream(test, GFP_KERNEL);
> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
> +
> + /* This should call the stub function. */
> + kunit_free_string_stream(test, stream);
> +
> + KUNIT_EXPECT_PTR_EQ(test, priv->freed_stream, stream);
> + KUNIT_EXPECT_FALSE(test, priv->stream_free_again);

Stream is never freed here?

We need to free stream here.

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[Richard Fitzgerald]

On 25/08/2023 07:49, David Gow wrote:
> On Thu, 24 Aug 2023 at 22:32, 'Richard Fitzgerald' via KUnit
> Development <kuni...@googlegroups.com> wrote:
>>
>> string_stream_managed_free_test() allocates a resource-managed
>> string_stream and tests that kunit_free_string_stream() calls
>> string_stream_destroy().
>>
>> string_stream_resource_free_test() allocates a resource-managed
>> string_stream and tests that string_stream_destroy() is called
>> when the test resources are cleaned up.
>>
>> The old string_stream_init_test() has been split into two tests,
>> one for kunit_alloc_string_stream() and the other for
>> alloc_string_stream().
>>
>> Signed-off-by: Richard Fitzgerald <r...@opensource.cirrus.com>
>> ---
>> Changes since V4:
>> - Added test case for kunit_free_string_stream().
>> - Split the initialization test into separate tests for managed and
>> unmanaged allocations.
>> ---
>
> Looking over this again, I'm not convinced the streams are actually
> getting freed. Once the stub has finished, the stream is removed from
> the list of deferred actions / resources.
>

Argh, I think you're right. My original version stashed the stream into
the private data and freed it in a test exit() function so that it was
guaranteed to be freed even if the resource cleanup wasn't called and
the test function aborted before it could do a manual cleanup.
I decided to simplify that but actually that original implementation was
better.