drm/mode: Add user blob-creation ioctl

Add an ioctl which allows users to create blob properties from supplied
data. Currently this only supports modes, creating a drm_display_mode from
the userspace drm_mode_modeinfo.

v2: Removed size/type checks.
    Rebased on new patches to allow error propagation from create_blob,
    as well as avoiding double-allocation.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@intel.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 0f6a5c8..c59ce4d 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -167,6 +167,7 @@
 	INIT_LIST_HEAD(&priv->lhead);
 	INIT_LIST_HEAD(&priv->fbs);
 	mutex_init(&priv->fbs_lock);
+	INIT_LIST_HEAD(&priv->blobs);
 	INIT_LIST_HEAD(&priv->event_list);
 	init_waitqueue_head(&priv->event_wait);
 	priv->event_space = 4096; /* set aside 4k for event buffer */
@@ -405,8 +406,10 @@
 
 	drm_events_release(file_priv);
 
-	if (drm_core_check_feature(dev, DRIVER_MODESET))
+	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
 		drm_fb_release(file_priv);
+		drm_property_destroy_user_blobs(dev, file_priv);
+	}
 
 	if (drm_core_check_feature(dev, DRIVER_GEM))
 		drm_gem_release(dev, file_priv);