[PATCH 7/9] drm: kselftest for drm_mm and top-down allocation

[Chris Wilson]

Check that if we request top-down allocation from drm_mm_insert_node()
we receive the next available hole from the top.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_mm_selftests.h |  1 +
 drivers/gpu/drm/test-drm_mm.c      | 96 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)

diff --git a/drivers/gpu/drm/drm_mm_selftests.h b/drivers/gpu/drm/drm_mm_selftests.h
index a3ee623b5f59..d435234e0e86 100644
--- a/drivers/gpu/drm/drm_mm_selftests.h
+++ b/drivers/gpu/drm/drm_mm_selftests.h
@@ -5,6 +5,7 @@
  *
  * Tests are executed in reverse order by igt/drm_mm
  */
+selftest(topdown, igt_topdown)
 selftest(evict, igt_evict)
 selftest(align64, igt_align64)
 selftest(align32, igt_align32)
diff --git a/drivers/gpu/drm/test-drm_mm.c b/drivers/gpu/drm/test-drm_mm.c
index ab9ddfba5cf5..270d0732f1ab 100644
--- a/drivers/gpu/drm/test-drm_mm.c
+++ b/drivers/gpu/drm/test-drm_mm.c
@@ -942,6 +942,102 @@ static int igt_evict(void *ignored)
 	return ret;
 }
 
+static int igt_topdown(void *ignored)
+{
+	const int size = 8192;
+	unsigned long *bitmap;
+	struct drm_mm mm;
+	struct drm_mm_node *nodes, *node, *next;
+	int *order, n, m, o = 0;
+	int ret;
+
+	ret = -ENOMEM;
+	nodes = vzalloc(size * sizeof(*nodes));
+	if (!nodes)
+		goto err;
+
+	bitmap = kzalloc(size / BITS_PER_LONG * sizeof(unsigned long),
+			 GFP_TEMPORARY);
+	if (!bitmap)
+		goto err_nodes;
+
+	order = random_order(size);
+	if (!order)
+		goto err_bitmap;
+
+	ret = -EINVAL;
+	drm_mm_init(&mm, 0, size);
+	for (n = 0; n < size; n++) {
+		int err;
+
+		err = drm_mm_insert_node_generic(&mm, &nodes[n], 1, 0, 0,
+						 DRM_MM_SEARCH_BELOW,
+						 DRM_MM_CREATE_TOP);
+		if (err) {
+			pr_err("insert failed, step %d\n", n);
+			ret = err;
+			goto out;
+		}
+
+		if (nodes[n].hole_follows) {
+			pr_err("hole after topdown insert %d, start=%llx\n",
+			       n, nodes[n].start);
+			goto out;
+		}
+	}
+
+	for_each_prime(n, size) {
+		for (m = 0; m < n; m++) {
+			node = &nodes[order[(o + m) % size]];
+			drm_mm_remove_node(node);
+			__set_bit(node->start, bitmap);
+		}
+
+		for (m = 0; m < n; m++) {
+			int err, last;
+
+			node = &nodes[order[(o + m) % size]];
+			err = drm_mm_insert_node_generic(&mm, node, 1, 0, 0,
+							 DRM_MM_SEARCH_BELOW,
+							 DRM_MM_CREATE_TOP);
+			if (err) {
+				pr_err("insert failed, step %d/%d\n", m, n);
+				ret = err;
+				goto out;
+			}
+
+			if (node->hole_follows) {
+				pr_err("hole after topdown insert %d/%d, start=%llx\n",
+				       m, n, node->start);
+				goto out;
+			}
+
+			last = find_last_bit(bitmap, size);
+			if (node->start != last) {
+				pr_err("node %d/%d not inserted into upmost hole, expected %d, found %lld\n",
+				       m, n, last, node->start);
+				goto out;
+			}
+			__clear_bit(last, bitmap);
+		}
+
+		o += n;
+	}
+
+	ret = 0;
+out:
+	list_for_each_entry_safe(node, next, &mm.head_node.node_list, node_list)
+		drm_mm_remove_node(node);
+	drm_mm_takedown(&mm);
+	kfree(order);
+err_bitmap:
+	kfree(bitmap);
+err_nodes:
+	vfree(nodes);
+err:
+	return ret;
+}
+
 #include "drm_selftest.c"
 
 static int __init test_drm_mm_init(void)
-- 
2.11.0