[PATCH v5] resource: add a simple test for walk_iomem_res_desc()

[Chia-I Wu]

This mainly tests that find_next_iomem_res() does not miss resources.

Signed-off-by: Chia-I Wu <olvaffe@xxxxxxxxx>

---
v2: update subject, use DEFINE_RES_NAMED and hardcoded offsets
v3: really hardcode offsets, with 4KB intervals since 0x1000 is easier
    to read than 0x400
v4: use RESOURCE_SIZE_MAX, split allocate_resource and KUNIT_ASSERT_EQ,
    and other cosmetic changes
v5: include linux/limits.h, add a comment on the resource layout, and
    add more negative tests for holes
---
 kernel/resource_kunit.c | 99 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/kernel/resource_kunit.c b/kernel/resource_kunit.c
index 58ab9f914602b..b13f01f290606 100644
--- a/kernel/resource_kunit.c
+++ b/kernel/resource_kunit.c
@@ -6,6 +6,7 @@
 #include <kunit/test.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
+#include <linux/limits.h>
 #include <linux/string.h>
 
 #define R0_START	0x0000
@@ -137,9 +138,107 @@ static void resource_test_intersection(struct kunit *test)
 	} while (++i < ARRAY_SIZE(results_for_intersection));
 }
 
+static int resource_walk_count(struct resource *res, void *data)
+{
+	int *count = data;
+
+	(*count)++;
+	return 0;
+}
+
+static void resource_test_walk_iomem_res_desc(struct kunit *test)
+{
+	struct resource root = {
+		.name = "Resource Walk Test",
+	};
+	struct resource res[8];
+	int count;
+	int ret;
+
+	ret = allocate_resource(&iomem_resource, &root, 0x100000,
+			0, RESOURCE_SIZE_MAX, 0x100000, NULL, NULL);
+	KUNIT_ASSERT_EQ(test, 0, ret);
+
+	/* build the resource tree under the test root:
+	 *
+	 *   0x0000-0x0fff: res[0], a match
+	 *   0x1000-0x1fff: res[1], a non-match
+	 *   0x2000-0x2fff: a hole
+	 *   0x3000-0x3fff: res[2], a non-match
+	 *     0x3800-0x3bff: res[3], a match
+	 *   0x4000-0x4fff: res[4], a match
+	 */
+	res[0] = DEFINE_RES_NAMED(root.start + 0x0000, 0x1000, "SYSRAM 1",
+			IORESOURCE_SYSTEM_RAM);
+	res[1] = DEFINE_RES_NAMED(root.start + 0x1000, 0x1000, "OTHER", 0);
+
+	res[2] = DEFINE_RES_NAMED(root.start + 0x3000, 0x1000, "NESTED", 0);
+	res[3] = DEFINE_RES_NAMED(root.start + 0x3800, 0x0400, "SYSRAM 2",
+			IORESOURCE_SYSTEM_RAM);
+
+	res[4] = DEFINE_RES_NAMED(root.start + 0x4000, 0x1000, "SYSRAM 3",
+			IORESOURCE_SYSTEM_RAM);
+
+	KUNIT_EXPECT_EQ(test, 0, request_resource(&root, &res[0]));
+	KUNIT_EXPECT_EQ(test, 0, request_resource(&root, &res[1]));
+	KUNIT_EXPECT_EQ(test, 0, request_resource(&root, &res[2]));
+	KUNIT_EXPECT_EQ(test, 0, request_resource(&res[2], &res[3]));
+	KUNIT_EXPECT_EQ(test, 0, request_resource(&root, &res[4]));
+
+	/* walk the entire region */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			root.start, root.end, &count, resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 3);
+
+	/* walk the region requested by res[0] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[0].start, res[0].end, &count, resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 1);
+
+	/* walk the region requested by res[1] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[1].start, res[1].end, &count, resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 0);
+
+	/* walk the hole between res[1] and res[2] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[1].end + 1, res[2].start - 1, &count,
+			resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 0);
+
+	/* walk the region requested by res[2] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[2].start, res[2].end, &count, resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 1);
+
+	/* walk the holes before and after res[3] nested under res[2] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[2].start, res[3].start - 1, &count,
+			resource_walk_count);
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[2].end + 1, res[3].end, &count,
+			resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 0);
+
+	/* walk the region requested by res[4] */
+	count = 0;
+	walk_iomem_res_desc(IORES_DESC_NONE, IORESOURCE_SYSTEM_RAM,
+			res[4].start, res[4].end, &count, resource_walk_count);
+	KUNIT_EXPECT_EQ(test, count, 1);
+
+	release_resource(&root);
+}
+
 static struct kunit_case resource_test_cases[] = {
 	KUNIT_CASE(resource_test_union),
 	KUNIT_CASE(resource_test_intersection),
+	KUNIT_CASE(resource_test_walk_iomem_res_desc),
 	{}
 };
 
-- 
2.45.1.467.gbab1589fc0-goog