revocable: Add Kunit test cases

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.
- Try Access Macro: Same as "Revocation" but uses the
  REVOCABLE_TRY_ACCESS_WITH() and REVOCABLE_TRY_ACCESS_SCOPED().

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>
Link: https://patch.msgid.link/20260116080235.350305-3-tzungbi@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -22373,6 +22373,7 @@ 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

drivers/base/Kconfig

@@ -250,3 +250,11 @@ 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.

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

drivers/base/revocable_test.c

@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2026 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.
+ *
+ * - Try Access Macro: Same as "Revocation" but uses the
+ *   REVOCABLE_TRY_ACCESS_WITH() and REVOCABLE_TRY_ACCESS_SCOPED().
+ */
+
+#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_try_access_macro(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);
+
+	{
+		REVOCABLE_TRY_ACCESS_WITH(rev, res);
+		KUNIT_EXPECT_PTR_EQ(test, res, real_res);
+	}
+
+	revocable_provider_revoke(rp);
+
+	{
+		REVOCABLE_TRY_ACCESS_WITH(rev, res);
+		KUNIT_EXPECT_PTR_EQ(test, res, NULL);
+	}
+
+	revocable_free(rev);
+}
+
+static void revocable_test_try_access_macro2(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_SCOPED(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_SCOPED(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_try_access_macro),
+	KUNIT_CASE(revocable_test_try_access_macro2),
+	{}
+};
+
+static struct kunit_suite revocable_test_suite = {
+	.name = "revocable_test",
+	.test_cases = revocable_test_cases,
+};
+
+kunit_test_suite(revocable_test_suite);