From 0d67356de4e0c9e0d068ea9c16cf33df4fd13776 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>
Date: Mon, 28 Aug 2006 16:36:37 +0200
Subject: Proper TTM dereferencing Initial buffer object creation.

---
 linux-core/drm_ttm.c | 56 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 15 deletions(-)

(limited to 'linux-core/drm_ttm.c')

diff --git a/linux-core/drm_ttm.c b/linux-core/drm_ttm.c
index e76b41fb..cda3ec29 100644
--- a/linux-core/drm_ttm.c
+++ b/linux-core/drm_ttm.c
@@ -752,7 +752,6 @@ int drm_user_create_region(drm_device_t * dev, unsigned long start, int len,
 /*
  * dev->struct_mutex locked.
  */
-
 static void drm_ttm_object_remove(drm_device_t *dev, drm_ttm_object_t *object)
 {
 	drm_map_list_t *list = &object->map_list;
@@ -777,17 +776,24 @@ static void drm_ttm_object_remove(drm_device_t *dev, drm_ttm_object_t *object)
 	drm_free(object, sizeof(*object), DRM_MEM_TTM);
 }
 
+
+void drm_ttm_object_deref_locked(drm_device_t *dev, drm_ttm_object_t *to)
+{
+	if (atomic_dec_and_test(&to->usage)) {
+		drm_ttm_object_remove(dev, to);
+	}
+}
+
+
 /*
  * dev->struct_mutex locked.
  */
-static void drm_ttm_user_object_remove(drm_file_t *priv, drm_user_object_t *base)
+static void drm_ttm_user_deref_locked(drm_file_t *priv, drm_user_object_t *base)
 {
-	drm_ttm_object_t *object;
-	drm_device_t *dev = priv->head->dev;
-
-	object = drm_user_object_entry(base, drm_ttm_object_t, base);
-	if (atomic_dec_and_test(&object->usage)) 
-		drm_ttm_object_remove(dev, object);
+	DRM_ERROR("User deref ttm\n");
+	drm_ttm_object_deref_locked(priv->head->dev,
+				    drm_user_object_entry(base, drm_ttm_object_t, 
+							  base));
 }
 
 	
@@ -840,16 +846,33 @@ int drm_ttm_object_create(drm_device_t *dev, unsigned long size,
 	}
 
 	list->user_token = list->hash.key;
-	object->base.remove = drm_ttm_user_object_remove;
-	object->base.type = drm_ttm_type;
-	object->base.ref_struct_locked = NULL;
-	object->base.unref = NULL;
 
 	atomic_set(&object->usage, 1);
 	*ttm_object = object;
 	return 0;
 }
 
+drm_ttm_object_t *drm_lookup_ttm_object(drm_file_t *priv, uint32_t handle, 
+					int check_owner)
+{
+	drm_user_object_t *uo;
+	drm_ttm_object_t *to;
+
+	uo = drm_lookup_user_object(priv, handle);
+
+	if (!uo || (uo->type != drm_ttm_type)) 
+		return NULL;
+
+	if (check_owner && priv != uo->owner) {
+		if (!drm_lookup_ref_object(priv, uo, _DRM_REF_USE))
+			return NULL;
+	}
+
+	to = drm_user_object_entry(uo, drm_ttm_object_t, base);
+	atomic_inc(&to->usage);
+	return to;
+}
+
 
 int drm_ttm_ioctl(DRM_IOCTL_ARGS)
 {
@@ -878,6 +901,10 @@ int drm_ttm_ioctl(DRM_IOCTL_ARGS)
 			mutex_unlock(&dev->struct_mutex);
 			return ret;
 		}
+		entry->base.remove = drm_ttm_user_deref_locked;
+		entry->base.type = drm_ttm_type;
+		entry->base.ref_struct_locked = NULL;
+		entry->base.unref = NULL;
 		atomic_inc(&entry->usage);
 		break;
 	case drm_ttm_reference:
@@ -885,8 +912,7 @@ int drm_ttm_ioctl(DRM_IOCTL_ARGS)
 		if (ret)
 			return ret;
 		mutex_lock(&dev->struct_mutex);
-		uo = drm_lookup_user_object(priv, arg.handle);
-		entry = drm_user_object_entry(uo, drm_ttm_object_t, base);
+		entry = drm_lookup_ttm_object(priv, arg.handle , 0);
 		break;
 	case drm_ttm_unreference:
 		return drm_user_object_unref(priv, arg.handle, drm_ttm_type);
@@ -904,7 +930,7 @@ int drm_ttm_ioctl(DRM_IOCTL_ARGS)
 	arg.handle = entry->base.hash.key;
 	arg.user_token = entry->map_list.user_token;
 	arg.size = drm_u64(entry->map_list.map->size);
-	atomic_dec(&entry->usage);
+	drm_ttm_object_deref_locked(dev, entry);
 	mutex_unlock(&dev->struct_mutex);
 
 	DRM_COPY_TO_USER_IOCTL((void __user *)data, arg, sizeof(arg));
-- 
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