[PATCH v4 2/7] revocable: Add Kunit test cases

[Tzung-Bi Shih <tzungbi@kernel.org>]

Add Kunit test cases for the revocable API.

The test cases cover the following scenarios:
- Basic: Verifies that a consumer can successfully access the resource
  provided via the provider.
- Revocation: Verifies that after the provider revokes the resource,
  the consumer correctly receives a NULL pointer on a subsequent access.
- Macro: Same as "Revocation" but uses the REVOCABLE().

A way to run the test:
$ ./tools/testing/kunit/kunit.py run \
        --kconfig_add CONFIG_REVOCABLE_KUNIT_TEST=y \
        revocable_test

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
---
v4:
- REVOCABLE() -> REVOCABLE_TRY_ACCESS_WITH().
- revocable_release() -> revocable_withdraw_access().

v3: https://lore.kernel.org/chrome-platform/20250912081718.3827390-3-tzungbi@kernel.org
- No changes.

v2: https://lore.kernel.org/chrome-platform/20250820081645.847919-3-tzungbi@kernel.org
- New in the series.

 MAINTAINERS                   |   1 +
 drivers/base/Kconfig          |   8 +++
 drivers/base/Makefile         |   3 +
 drivers/base/revocable_test.c | 110 ++++++++++++++++++++++++++++++++++
 4 files changed, 122 insertions(+)
 create mode 100644 drivers/base/revocable_test.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 15d45289fda6..1f12100d1ab7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21957,6 +21957,7 @@ M:	Tzung-Bi Shih <tzungbi@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 F:	drivers/base/revocable.c
+F:	drivers/base/revocable_test.c
 F:	include/linux/revocable.h
 
 RFKILL
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 064eb52ff7e2..a6488035f63d 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -244,3 +244,11 @@ config FW_DEVLINK_SYNC_STATE_TIMEOUT
 	  work on.
 
 endmenu
+
+# Kunit test cases
+config REVOCABLE_KUNIT_TEST
+	tristate "Kunit tests for revocable" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Kunit tests for the revocable API.
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index bdf854694e39..4185aaa9bbb9 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -35,3 +35,6 @@ ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
 # define_trace.h needs to know how to find our header
 CFLAGS_trace.o		:= -I$(src)
 obj-$(CONFIG_TRACING)	+= trace.o
+
+# Kunit test cases
+obj-$(CONFIG_REVOCABLE_KUNIT_TEST)	+= revocable_test.o
diff --git a/drivers/base/revocable_test.c b/drivers/base/revocable_test.c
new file mode 100644
index 000000000000..1c3e08ba0505
--- /dev/null
+++ b/drivers/base/revocable_test.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Kunit tests for the revocable API.
+ *
+ * The test cases cover the following scenarios:
+ *
+ * - Basic: Verifies that a consumer can successfully access the resource
+ *   provided via the provider.
+ *
+ * - Revocation: Verifies that after the provider revokes the resource,
+ *   the consumer correctly receives a NULL pointer on a subsequent access.
+ *
+ * - Macro: Same as "Revocation" but uses the REVOCABLE_TRY_ACCESS_WITH().
+ */
+
+#include <kunit/test.h>
+#include <linux/revocable.h>
+
+static void revocable_test_basic(struct kunit *test)
+{
+	struct revocable_provider *rp;
+	struct revocable *rev;
+	void *real_res = (void *)0x12345678, *res;
+
+	rp = revocable_provider_alloc(real_res);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rp);
+
+	rev = revocable_alloc(rp);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rev);
+
+	res = revocable_try_access(rev);
+	KUNIT_EXPECT_PTR_EQ(test, res, real_res);
+	revocable_withdraw_access(rev);
+
+	revocable_free(rev);
+	revocable_provider_revoke(rp);
+}
+
+static void revocable_test_revocation(struct kunit *test)
+{
+	struct revocable_provider *rp;
+	struct revocable *rev;
+	void *real_res = (void *)0x12345678, *res;
+
+	rp = revocable_provider_alloc(real_res);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rp);
+
+	rev = revocable_alloc(rp);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rev);
+
+	res = revocable_try_access(rev);
+	KUNIT_EXPECT_PTR_EQ(test, res, real_res);
+	revocable_withdraw_access(rev);
+
+	revocable_provider_revoke(rp);
+
+	res = revocable_try_access(rev);
+	KUNIT_EXPECT_PTR_EQ(test, res, NULL);
+	revocable_withdraw_access(rev);
+
+	revocable_free(rev);
+}
+
+static void revocable_test_macro(struct kunit *test)
+{
+	struct revocable_provider *rp;
+	struct revocable *rev;
+	void *real_res = (void *)0x12345678, *res;
+	bool accessed;
+
+	rp = revocable_provider_alloc(real_res);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rp);
+
+	rev = revocable_alloc(rp);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, rev);
+
+	accessed = false;
+	REVOCABLE_TRY_ACCESS_WITH(rev, res) {
+		KUNIT_EXPECT_PTR_EQ(test, res, real_res);
+		accessed = true;
+	}
+	KUNIT_EXPECT_TRUE(test, accessed);
+
+	revocable_provider_revoke(rp);
+
+	accessed = false;
+	REVOCABLE_TRY_ACCESS_WITH(rev, res) {
+		KUNIT_EXPECT_PTR_EQ(test, res, NULL);
+		accessed = true;
+	}
+	KUNIT_EXPECT_TRUE(test, accessed);
+
+	revocable_free(rev);
+}
+
+static struct kunit_case revocable_test_cases[] = {
+	KUNIT_CASE(revocable_test_basic),
+	KUNIT_CASE(revocable_test_revocation),
+	KUNIT_CASE(revocable_test_macro),
+	{}
+};
+
+static struct kunit_suite revocable_test_suite = {
+	.name = "revocable_test",
+	.test_cases = revocable_test_cases,
+};
+
+kunit_test_suite(revocable_test_suite);
-- 
2.51.0.534.gc79095c0ca-goog