drm: kselftest for drm_mm and bottom-up allocation

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

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170202114434.3060-2-chris@chris-wilson.co.uk

drivers/gpu/drm/selftests/drm_mm_selftests.h

@@ -17,6 +17,7 @@ selftest(align32, igt_align32)
 selftest(align64, igt_align64)
 selftest(evict, igt_evict)
 selftest(evict_range, igt_evict_range)
+selftest(bottomup, igt_bottomup)
 selftest(topdown, igt_topdown)
 selftest(color, igt_color)
 selftest(color_evict, igt_color_evict)

drivers/gpu/drm/selftests/test-drm_mm.c

@@ -1697,6 +1697,106 @@ err:
 	return ret;
 }
 
+static int igt_bottomup(void *ignored)
+{
+	const struct insert_mode *bottomup = &insert_modes[BOTTOMUP];
+	DRM_RND_STATE(prng, random_seed);
+	const unsigned int count = 8192;
+	unsigned int size;
+	unsigned long *bitmap;
+	struct drm_mm mm;
+	struct drm_mm_node *nodes, *node, *next;
+	unsigned int *order, n, m, o = 0;
+	int ret;
+
+	/* Like igt_topdown, but instead of searching for the last hole,
+	 * we search for the first.
+	 */
+
+	ret = -ENOMEM;
+	nodes = vzalloc(count * sizeof(*nodes));
+	if (!nodes)
+		goto err;
+
+	bitmap = kzalloc(count / BITS_PER_LONG * sizeof(unsigned long),
+			 GFP_TEMPORARY);
+	if (!bitmap)
+		goto err_nodes;
+
+	order = drm_random_order(count, &prng);
+	if (!order)
+		goto err_bitmap;
+
+	ret = -EINVAL;
+	for (size = 1; size <= 64; size <<= 1) {
+		drm_mm_init(&mm, 0, size*count);
+		for (n = 0; n < count; n++) {
+			if (!expect_insert(&mm, &nodes[n],
+					   size, 0, n,
+					   bottomup)) {
+				pr_err("bottomup insert failed, size %u step %d\n", size, n);
+				goto out;
+			}
+
+			if (!assert_one_hole(&mm, size*(n + 1), size*count))
+				goto out;
+		}
+
+		if (!assert_continuous(&mm, size))
+			goto out;
+
+		drm_random_reorder(order, count, &prng);
+		for_each_prime_number_from(n, 1, min(count, max_prime)) {
+			for (m = 0; m < n; m++) {
+				node = &nodes[order[(o + m) % count]];
+				drm_mm_remove_node(node);
+				__set_bit(node_index(node), bitmap);
+			}
+
+			for (m = 0; m < n; m++) {
+				unsigned int first;
+
+				node = &nodes[order[(o + m) % count]];
+				if (!expect_insert(&mm, node,
+						   size, 0, 0,
+						   bottomup)) {
+					pr_err("insert failed, step %d/%d\n", m, n);
+					goto out;
+				}
+
+				first = find_first_bit(bitmap, count);
+				if (node_index(node) != first) {
+					pr_err("node %d/%d not inserted into bottom hole, expected %d, found %d\n",
+					       m, n, first, node_index(node));
+					goto out;
+				}
+				__clear_bit(first, bitmap);
+			}
+
+			DRM_MM_BUG_ON(find_first_bit(bitmap, count) != count);
+
+			o += n;
+		}
+
+		drm_mm_for_each_node_safe(node, next, &mm)
+			drm_mm_remove_node(node);
+		DRM_MM_BUG_ON(!drm_mm_clean(&mm));
+	}
+
+	ret = 0;
+out:
+	drm_mm_for_each_node_safe(node, next, &mm)
+		drm_mm_remove_node(node);
+	drm_mm_takedown(&mm);
+	kfree(order);
+err_bitmap:
+	kfree(bitmap);
+err_nodes:
+	vfree(nodes);
+err:
+	return ret;
+}
+
 static void separate_adjacent_colors(const struct drm_mm_node *node,
 				     unsigned long color,
 				     u64 *start,