linux-kernel - [PATCH v2 5/5] kunit: make kunit_kfree(NULL) a no-op to match kfree()

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Date:   Fri, 22 Jul 2022 17:15:34 +0000
From:   Daniel Latypov <dlatypov@...gle.com>
To:     brendanhiggins@...gle.com, davidgow@...gle.com
Cc:     linux-kernel@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kselftest@...r.kernel.org, skhan@...uxfoundation.org,
        Daniel Latypov <dlatypov@...gle.com>
Subject: [PATCH v2 5/5] kunit: make kunit_kfree(NULL) a no-op to match kfree()

The real kfree() function will silently return when given a NULL.
So a user might reasonably think they can write the following code:
  char *buffer = NULL;
  if (param->use_buffer) buffer = kunit_kzalloc(test, 10, GFP_KERNEL);
  ...
  kunit_kfree(test, buffer);

As-is, kunit_kfree() will mark the test as FAILED when buffer is NULL.
(And in earlier times, it would segfault).

Let's match the semantics of kfree().

Suggested-by: David Gow <davidgow@...gle.com>
Signed-off-by: Daniel Latypov <dlatypov@...gle.com>
---
v1 -> v2: add this patch to the series.
---
 lib/kunit/test.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index c7ca87484968..879c8db36cb5 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -698,6 +698,9 @@ static inline bool kunit_kfree_match(struct kunit *test,
 
 void kunit_kfree(struct kunit *test, const void *ptr)
 {
+	if (!ptr)
+		return;
+
 	if (kunit_destroy_resource(test, kunit_kfree_match, (void *)ptr))
 		KUNIT_FAIL(test, "kunit_kfree: %px already freed or not allocated by kunit", ptr);
 }
-- 
2.37.1.359.gd136c6c3e2-goog