drm/ttm: Use the hashtab _rcu interface for ttm_objects

Also move a kref_init() out of spinlocked region
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_object.c

@@ -157,9 +157,9 @@ int ttm_base_object_init(struct ttm_object_file *tfile,
 	base->refcount_release = refcount_release;
 	base->ref_obj_release = ref_obj_release;
 	base->object_type = object_type;
-	spin_lock(&tdev->object_lock);
 	kref_init(&base->refcount);
-	ret = drm_ht_just_insert_please(&tdev->object_hash,
+	spin_lock(&tdev->object_lock);
+	ret = drm_ht_just_insert_please_rcu(&tdev->object_hash,
 					    &base->hash,
 					    (unsigned long)base, 31, 0, 0);
 	spin_unlock(&tdev->object_lock);
@@ -175,7 +175,7 @@ int ttm_base_object_init(struct ttm_object_file *tfile,
 	return 0;
 out_err1:
 	spin_lock(&tdev->object_lock);
-	(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
+	(void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 	spin_unlock(&tdev->object_lock);
 out_err0:
 	return ret;
@@ -189,8 +189,15 @@ static void ttm_release_base(struct kref *kref)
 	struct ttm_object_device *tdev = base->tfile->tdev;
 
 	spin_lock(&tdev->object_lock);
-	(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
+	(void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 	spin_unlock(&tdev->object_lock);
+
+	/*
+	 * Note: We don't use synchronize_rcu() here because it's far
+	 * too slow. It's up to the user to free the object using
+	 * call_rcu() or ttm_base_object_kfree().
+	 */
+
 	if (base->refcount_release) {
 		ttm_object_file_unref(&base->tfile);
 		base->refcount_release(&base);
@@ -216,7 +223,7 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
 	int ret;
 
 	rcu_read_lock();
-	ret = drm_ht_find_item(&tdev->object_hash, key, &hash);
+	ret = drm_ht_find_item_rcu(&tdev->object_hash, key, &hash);
 
 	if (likely(ret == 0)) {
 		base = drm_hash_entry(hash, struct ttm_base_object, hash);