3 files changed, 158 insertions, 5 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 6c9f19911be0..dddf51266719 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_HAS_IOMEM) += iomem.o
 obj-$(CONFIG_RSEQ) += rseq.o
 obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o
 
+obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o
 obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
 
 CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN)
diff --git a/kernel/resource.c b/kernel/resource.c
index 3ae2f56cc79d..82df80417489 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -557,13 +557,13 @@ int region_intersects(resource_size_t start, size_t size, unsigned long flags,
 	}
 	read_unlock(&resource_lock);
 
-	if (other == 0)
-		return type ? REGION_INTERSECTS : REGION_DISJOINT;
+	if (type == 0)
+		return REGION_DISJOINT;
 
-	if (type)
-		return REGION_MIXED;
+	if (other == 0)
+		return REGION_INTERSECTS;
 
-	return REGION_DISJOINT;
+	return REGION_MIXED;
 }
 EXPORT_SYMBOL_GPL(region_intersects);
 
diff --git a/kernel/resource_kunit.c b/kernel/resource_kunit.c
new file mode 100644
index 000000000000..58ab9f914602
--- /dev/null
+++ b/kernel/resource_kunit.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Test cases for API provided by resource.c and ioport.h
+ */
+
+#include <kunit/test.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+
+#define R0_START	0x0000
+#define R0_END		0xffff
+#define R1_START	0x1234
+#define R1_END		0x2345
+#define R2_START	0x4567
+#define R2_END		0x5678
+#define R3_START	0x6789
+#define R3_END		0x789a
+#define R4_START	0x2000
+#define R4_END		0x7000
+
+static struct resource r0 = { .start = R0_START, .end = R0_END };
+static struct resource r1 = { .start = R1_START, .end = R1_END };
+static struct resource r2 = { .start = R2_START, .end = R2_END };
+static struct resource r3 = { .start = R3_START, .end = R3_END };
+static struct resource r4 = { .start = R4_START, .end = R4_END };
+
+struct result {
+	struct resource *r1;
+	struct resource *r2;
+	struct resource r;
+	bool ret;
+};
+
+static struct result results_for_union[] = {
+	{
+		.r1 = &r1, .r2 = &r0, .r.start = R0_START, .r.end = R0_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r0, .r.start = R0_START, .r.end = R0_END, .ret = true,
+	}, {
+		.r1 = &r3, .r2 = &r0, .r.start = R0_START, .r.end = R0_END, .ret = true,
+	}, {
+		.r1 = &r4, .r2 = &r0, .r.start = R0_START, .r.end = R0_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r1, .ret = false,
+	}, {
+		.r1 = &r3, .r2 = &r1, .ret = false,
+	}, {
+		.r1 = &r4, .r2 = &r1, .r.start = R1_START, .r.end = R4_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r3, .ret = false,
+	}, {
+		.r1 = &r2, .r2 = &r4, .r.start = R4_START, .r.end = R4_END, .ret = true,
+	}, {
+		.r1 = &r3, .r2 = &r4, .r.start = R4_START, .r.end = R3_END, .ret = true,
+	},
+};
+
+static struct result results_for_intersection[] = {
+	{
+		.r1 = &r1, .r2 = &r0, .r.start = R1_START, .r.end = R1_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r0, .r.start = R2_START, .r.end = R2_END, .ret = true,
+	}, {
+		.r1 = &r3, .r2 = &r0, .r.start = R3_START, .r.end = R3_END, .ret = true,
+	}, {
+		.r1 = &r4, .r2 = &r0, .r.start = R4_START, .r.end = R4_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r1, .ret = false,
+	}, {
+		.r1 = &r3, .r2 = &r1, .ret = false,
+	}, {
+		.r1 = &r4, .r2 = &r1, .r.start = R4_START, .r.end = R1_END, .ret = true,
+	}, {
+		.r1 = &r2, .r2 = &r3, .ret = false,
+	}, {
+		.r1 = &r2, .r2 = &r4, .r.start = R2_START, .r.end = R2_END, .ret = true,
+	}, {
+		.r1 = &r3, .r2 = &r4, .r.start = R3_START, .r.end = R4_END, .ret = true,
+	},
+};
+
+static void resource_do_test(struct kunit *test, bool ret, struct resource *r,
+			     bool exp_ret, struct resource *exp_r,
+			     struct resource *r1, struct resource *r2)
+{
+	KUNIT_EXPECT_EQ_MSG(test, ret, exp_ret, "Resources %pR %pR", r1, r2);
+	KUNIT_EXPECT_EQ_MSG(test, r->start, exp_r->start, "Start elements are not equal");
+	KUNIT_EXPECT_EQ_MSG(test, r->end, exp_r->end, "End elements are not equal");
+}
+
+static void resource_do_union_test(struct kunit *test, struct result *r)
+{
+	struct resource result;
+	bool ret;
+
+	memset(&result, 0, sizeof(result));
+	ret = resource_union(r->r1, r->r2, &result);
+	resource_do_test(test, ret, &result, r->ret, &r->r, r->r1, r->r2);
+
+	memset(&result, 0, sizeof(result));
+	ret = resource_union(r->r2, r->r1, &result);
+	resource_do_test(test, ret, &result, r->ret, &r->r, r->r2, r->r1);
+}
+
+static void resource_test_union(struct kunit *test)
+{
+	struct result *r = results_for_union;
+	unsigned int i = 0;
+
+	do {
+		resource_do_union_test(test, &r[i]);
+	} while (++i < ARRAY_SIZE(results_for_union));
+}
+
+static void resource_do_intersection_test(struct kunit *test, struct result *r)
+{
+	struct resource result;
+	bool ret;
+
+	memset(&result, 0, sizeof(result));
+	ret = resource_intersection(r->r1, r->r2, &result);
+	resource_do_test(test, ret, &result, r->ret, &r->r, r->r1, r->r2);
+
+	memset(&result, 0, sizeof(result));
+	ret = resource_intersection(r->r2, r->r1, &result);
+	resource_do_test(test, ret, &result, r->ret, &r->r, r->r2, r->r1);
+}
+
+static void resource_test_intersection(struct kunit *test)
+{
+	struct result *r = results_for_intersection;
+	unsigned int i = 0;
+
+	do {
+		resource_do_intersection_test(test, &r[i]);
+	} while (++i < ARRAY_SIZE(results_for_intersection));
+}
+
+static struct kunit_case resource_test_cases[] = {
+	KUNIT_CASE(resource_test_union),
+	KUNIT_CASE(resource_test_intersection),
+	{}
+};
+
+static struct kunit_suite resource_test_suite = {
+	.name = "resource",
+	.test_cases = resource_test_cases,
+};
+kunit_test_suite(resource_test_suite);
+
+MODULE_LICENSE("GPL");