[PATCH] mm/damon/core-test: Add a kunit test case for ops registration

[SeongJae Park <sj@xxxxxxxxxx>]

This commit adds a simple kunit test case for DAMON operations
registration feature.

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 mm/damon/core-test.h | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/mm/damon/core-test.h b/mm/damon/core-test.h
index b4085deb9fa0..573669566f84 100644
--- a/mm/damon/core-test.h
+++ b/mm/damon/core-test.h
@@ -232,6 +232,41 @@ static void damon_test_split_regions_of(struct kunit *test)
 	damon_destroy_ctx(c);
 }
 
+static void damon_test_ops_registration(struct kunit *test)
+{
+	struct damon_ctx *c = damon_new_ctx();
+	struct damon_operations ops, bak;
+
+	/* DAMON_OPS_{V,P}ADDR are registered on subsys_initcall */
+	KUNIT_EXPECT_EQ(test, damon_select_ops(c, DAMON_OPS_VADDR), 0);
+	KUNIT_EXPECT_EQ(test, damon_select_ops(c, DAMON_OPS_PADDR), 0);
+
+	/* Double-registration is prohibited */
+	ops.id = DAMON_OPS_VADDR;
+	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), -EINVAL);
+	ops.id = DAMON_OPS_PADDR;
+	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), -EINVAL);
+
+	/* Unknown ops id cannot be registered */
+	KUNIT_EXPECT_EQ(test, damon_select_ops(c, NR_DAMON_OPS), -EINVAL);
+
+	/* Registration should success after unregistration */
+	mutex_lock(&damon_ops_lock);
+	bak = damon_registered_ops[DAMON_OPS_VADDR];
+	damon_registered_ops[DAMON_OPS_VADDR] = (struct damon_operations){};
+	mutex_unlock(&damon_ops_lock);
+
+	ops.id = DAMON_OPS_VADDR;
+	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), 0);
+
+	mutex_lock(&damon_ops_lock);
+	damon_registered_ops[DAMON_OPS_VADDR] = bak;
+	mutex_unlock(&damon_ops_lock);
+
+	/* Check double-registration failure again */
+	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), -EINVAL);
+}
+
 static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_target),
 	KUNIT_CASE(damon_test_regions),
@@ -240,6 +275,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_merge_two),
 	KUNIT_CASE(damon_test_merge_regions_of),
 	KUNIT_CASE(damon_test_split_regions_of),
+	KUNIT_CASE(damon_test_ops_registration),
 	{},
 };
 
-- 
2.25.1