[PATCH 30/34] drm: pre allocate node for create_block

[Ben Widawsky <ben@bwidawsk.net>]

For an upcoming patch where we introduce the i915 VMA, it's ideal to
have the drm_mm_node as part of the VMA struct (ie. it's pre-allocated).
Part of the conversion to VMAs is to kill off obj->gtt_space. Doing this
will break a bunch of code, but amongst them are 2 callers of
drm_mm_create_block(), both related to stolen memory.

As a side note, this patch has is able to leverage all the existing
drm_mm_put_block because the node is still kzalloc'd. When the
aforementioned VMA code comes into play, that too has to change.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/drm_mm.c               | 16 +++++-----------
 drivers/gpu/drm/i915/i915_drv.h        |  2 +-
 drivers/gpu/drm/i915/i915_gem_gtt.c    | 20 ++++++++++++++-----
 drivers/gpu/drm/i915/i915_gem_stolen.c | 35 +++++++++++++++++++++++-----------
 include/drm/drm_mm.h                   |  9 ++++-----
 5 files changed, 49 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 7095328..a2dcfdb 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -158,12 +158,10 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 	}
 }
 
-struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
-					unsigned long start,
-					unsigned long size,
-					enum drm_mm_allocator_flags flags)
+int drm_mm_create_block(struct drm_mm *mm, struct drm_mm_node *node,
+			unsigned long start, unsigned long size)
 {
-	struct drm_mm_node *hole, *node;
+	struct drm_mm_node *hole;
 	unsigned long end = start + size;
 	unsigned long hole_start;
 	unsigned long hole_end;
@@ -172,10 +170,6 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
 		if (hole_start > start || hole_end < end)
 			continue;
 
-		node = drm_mm_kmalloc(mm, flags & DRM_MM_CREATE_ATOMIC);
-		if (unlikely(node == NULL))
-			return NULL;
-
 		node->start = start;
 		node->size = size;
 		node->mm = mm;
@@ -195,11 +189,11 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
 			node->hole_follows = 1;
 		}
 
-		return node;
+		return 0;
 	}
 
 	WARN(1, "no hole found for block 0x%lx + 0x%lx\n", start, size);
-	return NULL;
+	return -ENOSPC;
 }
 EXPORT_SYMBOL(drm_mm_create_block);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 36f7d41..af1c797 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1123,7 +1123,7 @@ enum hdmi_force_audio {
 	HDMI_AUDIO_ON,			/* force turn on HDMI audio */
 };
 
-#define I915_GTT_RESERVED ((struct drm_mm_node *)0x1)
+#define I915_GTT_RESERVED 0x1
 
 struct drm_i915_gem_object_ops {
 	/* Interface between the GEM object and its backing storage.
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 17b846f..253d6e4 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -657,14 +657,24 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
 
 	/* Mark any preallocated objects as occupied */
 	list_for_each_entry(obj, &i915_gtt_vm->bound_list, gtt_list) {
+		uintptr_t gtt_offset = (uintptr_t)obj->gtt_space;
+		int ret;
 		DRM_DEBUG_KMS("reserving preallocated space: %lx + %zx\n",
 			      obj->gtt_space->start, obj->base.size);
 
-		BUG_ON(obj->gtt_space != I915_GTT_RESERVED);
-		obj->gtt_space = drm_mm_create_block(&i915_gtt_vm->mm,
-						     obj->gtt_space->start,
-						     obj->base.size,
-						     false);
+		BUG_ON((gtt_offset & I915_GTT_RESERVED) == 0);
+		gtt_offset = gtt_offset & ~I915_GTT_RESERVED;
+		obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
+		if (!obj->gtt_space) {
+			DRM_ERROR("Failed to preserve all objects\n");
+			break;
+		}
+		ret = drm_mm_create_block(&i915_gtt_vm->mm,
+					  obj->gtt_space,
+					  gtt_offset,
+					  obj->base.size);
+		if (ret)
+			DRM_DEBUG_KMS("Reservation failed\n");
 		obj->has_global_gtt_mapping = 1;
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index e494002..86c8feb 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -322,6 +322,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
 	struct drm_mm_node *stolen;
+	int ret;
 
 	if (dev_priv->gtt.stolen_base == 0)
 		return NULL;
@@ -337,11 +338,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	if (WARN_ON(size == 0))
 		return NULL;
 
-	stolen = drm_mm_create_block(&dev_priv->gtt.stolen,
-				     stolen_offset, size,
-				     false);
-	if (stolen == NULL) {
+	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
+	if (!stolen)
+		return NULL;
+
+	ret = drm_mm_create_block(&dev_priv->gtt.stolen, stolen, stolen_offset,
+				  size);
+	if (ret) {
 		DRM_DEBUG_KMS("failed to allocate stolen space\n");
+		kfree(stolen);
 		return NULL;
 	}
 
@@ -358,18 +363,26 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	 * later.
 	 */
 	if (drm_mm_initialized(&i915_gtt_vm->mm)) {
-		obj->gtt_space = drm_mm_create_block(&i915_gtt_vm->mm,
-						     gtt_offset, size,
-						     false);
-		if (obj->gtt_space == NULL) {
+		obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
+		if (!obj->gtt_space) {
+			drm_gem_object_unreference(&obj->base);
+			return NULL;
+		}
+		ret = drm_mm_create_block(&i915_gtt_vm->mm, obj->gtt_space,
+					  gtt_offset, size);
+		if (ret) {
 			DRM_DEBUG_KMS("failed to allocate stolen GTT space\n");
 			drm_gem_object_unreference(&obj->base);
+			kfree(obj->gtt_space);
 			return NULL;
 		}
-	} else
-		obj->gtt_space = I915_GTT_RESERVED;
+		obj->gtt_space->start = gtt_offset;
+	} else {
+		/* NB: Safe because we assert page alignment */
+		obj->gtt_space = (struct drm_mm_node *)
+			((uintptr_t)gtt_offset | I915_GTT_RESERVED);
+	}
 
-	obj->gtt_space->start = gtt_offset;
 	obj->has_global_gtt_mapping = 1;
 
 	list_add_tail(&obj->gtt_list, &i915_gtt_vm->bound_list);
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 8935710..0cfb06c 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -161,11 +161,10 @@ static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
 /*
  * Basic range manager support (drm_mm.c)
  */
-extern struct drm_mm_node *
-drm_mm_create_block(struct drm_mm *mm,
-		    unsigned long start,
-		    unsigned long size,
-		    enum drm_mm_allocator_flags flags);
+extern int drm_mm_create_block(struct drm_mm *mm,
+			       struct drm_mm_node *node,
+			       unsigned long start,
+			       unsigned long size);
 extern struct drm_mm_node *
 drm_mm_get_block_generic(struct drm_mm_node *node,
 			 unsigned long size,
-- 
1.8.2.3