Insulate users from changed to the internal hole tracking within
struct drm_mm_node by using an accessor for hole_follows.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_mm.c                | 12 ++++++------
 drivers/gpu/drm/i915/i915_vma.c         |  4 ++--
 drivers/gpu/drm/selftests/test-drm_mm.c | 18 ++++++++++--------
 include/drm/drm_mm.h                    | 22 +++++++++++++++++++---
 4 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 22db356e3ebc..da9f98690e97 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -323,7 +323,7 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct 
drm_mm_node *node)
        }

        hole = list_last_entry(&hole->node_list, typeof(*hole), node_list);
-       if (!hole->hole_follows)
+       if (!drm_mm_hole_follows(hole))
                return -ENOSPC;

        adj_start = hole_start = __drm_mm_hole_node_start(hole);
@@ -408,7 +408,7 @@ static void drm_mm_insert_helper_range(struct drm_mm_node 
*hole_node,
        u64 adj_start = hole_start;
        u64 adj_end = hole_end;

-       DRM_MM_BUG_ON(!hole_node->hole_follows || node->allocated);
+       DRM_MM_BUG_ON(!drm_mm_hole_follows(hole_node) || node->allocated);

        if (adj_start < start)
                adj_start = start;
@@ -523,16 +523,16 @@ void drm_mm_remove_node(struct drm_mm_node *node)
        prev_node =
            list_entry(node->node_list.prev, struct drm_mm_node, node_list);

-       if (node->hole_follows) {
+       if (drm_mm_hole_follows(node)) {
                DRM_MM_BUG_ON(__drm_mm_hole_node_start(node) ==
                              __drm_mm_hole_node_end(node));
                list_del(&node->hole_stack);
-       } else
+       } else {
                DRM_MM_BUG_ON(__drm_mm_hole_node_start(node) !=
                              __drm_mm_hole_node_end(node));
+       }

-
-       if (!prev_node->hole_follows) {
+       if (!drm_mm_hole_follows(prev_node)) {
                prev_node->hole_follows = 1;
                list_add(&prev_node->hole_stack, &mm->hole_stack);
        } else
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index f709c9b76358..34374c4133b5 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -322,11 +322,11 @@ bool i915_gem_valid_gtt_space(struct i915_vma *vma, 
unsigned long cache_level)
        GEM_BUG_ON(list_empty(&node->node_list));

        other = list_prev_entry(node, node_list);
-       if (color_differs(other, cache_level) && !other->hole_follows)
+       if (color_differs(other, cache_level) && !drm_mm_hole_follows(other))
                return false;

        other = list_next_entry(node, node_list);
-       if (color_differs(other, cache_level) && !node->hole_follows)
+       if (color_differs(other, cache_level) && !drm_mm_hole_follows(node))
                return false;

        return true;
diff --git a/drivers/gpu/drm/selftests/test-drm_mm.c 
b/drivers/gpu/drm/selftests/test-drm_mm.c
index 9899e8364350..a9ed018aac12 100644
--- a/drivers/gpu/drm/selftests/test-drm_mm.c
+++ b/drivers/gpu/drm/selftests/test-drm_mm.c
@@ -42,7 +42,7 @@ static bool assert_no_holes(const struct drm_mm *mm)
        }

        drm_mm_for_each_node(hole, mm) {
-               if (hole->hole_follows) {
+               if (drm_mm_hole_follows(hole)) {
                        pr_err("Hole follows node, expected none!\n");
                        return false;
                }
@@ -104,7 +104,7 @@ static bool assert_continuous(const struct drm_mm *mm, u64 
size)
                        return false;
                }

-               if (node->hole_follows) {
+               if (drm_mm_hole_follows(node)) {
                        pr_err("node[%ld] is followed by a hole!\n", n);
                        return false;
                }
@@ -787,7 +787,8 @@ static bool assert_contiguous_in_range(struct drm_mm *mm,
                        return false;
                }

-               if (node->hole_follows && drm_mm_hole_node_end(node) < end) {
+               if (drm_mm_hole_follows(node) &&
+                   drm_mm_hole_node_end(node) < end) {
                        pr_err("node %d is followed by a hole!\n", n);
                        return false;
                }
@@ -1307,11 +1308,12 @@ static int evict_something(struct drm_mm *mm,
                err = -EINVAL;
        }

-       if (!assert_node(&tmp, mm, size, alignment, 0) || tmp.hole_follows) {
+       if (!assert_node(&tmp, mm, size, alignment, 0) ||
+           drm_mm_hole_follows(&tmp)) {
                pr_err("Inserted did not fill the eviction hole: size=%lld 
[%d], align=%d [rem=%lld], start=%llx, hole-follows?=%d\n",
                       tmp.size, size,
                       alignment, misaligned(&tmp, alignment),
-                      tmp.start, tmp.hole_follows);
+                      tmp.start, drm_mm_hole_follows(&tmp));
                err = -EINVAL;
        }

@@ -1590,7 +1592,7 @@ static int igt_topdown(void *ignored)
                                goto out;
                        }

-                       if (nodes[n].hole_follows) {
+                       if (drm_mm_hole_follows(&nodes[n])) {
                                pr_err("hole after topdown insert %d, 
start=%llx\n, size=%u",
                                       n, nodes[n].start, size);
                                goto out;
@@ -1624,7 +1626,7 @@ static int igt_topdown(void *ignored)
                                        goto out;
                                }

-                               if (node->hole_follows) {
+                               if (drm_mm_hole_follows(node)) {
                                        pr_err("hole after topdown insert 
%d/%d, start=%llx\n",
                                               m, n, node->start);
                                        goto out;
@@ -1679,7 +1681,7 @@ static void separate_adjacent_colors(const struct 
drm_mm_node *node,

 static bool colors_abutt(const struct drm_mm_node *node)
 {
-       if (!node->hole_follows &&
+       if (!drm_mm_hole_follows(node) &&
            list_next_entry(node, node_list)->allocated) {
                pr_err("colors abutt; %ld [%llx + %llx] is next to %ld [%llx + 
%llx]!\n",
                       node->color, node->start, node->size,
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 6e5911fa9018..e78c01cf1135 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -155,6 +155,22 @@ static inline bool drm_mm_initialized(const struct drm_mm 
*mm)
        return mm->hole_stack.next;
 }

+/**
+ * drm_mm_hole_follows - checks whether a hole follows this node
+ * @node: drm_mm_node to check
+ *
+ * Holes are embedded into the drm_mm using the tail of a drm_mm_node.
+ * If you wish to know whether a hole follows this particular node,
+ * query this function.
+ *
+ * Returns:
+ * True if a hole follows the @node.
+ */
+static inline bool drm_mm_hole_follows(const struct drm_mm_node *node)
+{
+       return node->hole_follows;
+}
+
 static inline u64 __drm_mm_hole_node_start(const struct drm_mm_node *hole_node)
 {
        return hole_node->start + hole_node->size;
@@ -166,14 +182,14 @@ static inline u64 __drm_mm_hole_node_start(const struct 
drm_mm_node *hole_node)
  *
  * This is useful for driver-specific debug dumpers. Otherwise drivers should
  * not inspect holes themselves. Drivers must check first whether a hole indeed
- * follows by looking at node->hole_follows.
+ * follows by looking at drm_mm_hole_follows()
  *
  * Returns:
  * Start of the subsequent hole.
  */
 static inline u64 drm_mm_hole_node_start(const struct drm_mm_node *hole_node)
 {
-       DRM_MM_BUG_ON(!hole_node->hole_follows);
+       DRM_MM_BUG_ON(!drm_mm_hole_follows(hole_node));
        return __drm_mm_hole_node_start(hole_node);
 }

@@ -188,7 +204,7 @@ static inline u64 __drm_mm_hole_node_end(const struct 
drm_mm_node *hole_node)
  *
  * This is useful for driver-specific debug dumpers. Otherwise drivers should
  * not inspect holes themselves. Drivers must check first whether a hole indeed
- * follows by looking at node->hole_follows.
+ * follows by looking at drm_mm_hole_follows().
  *
  * Returns:
  * End of the subsequent hole.
-- 
2.11.0

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