drm/atomic: Fix bookkeeping with TEST_ONLY, v3.

Commit ec9f932e
"drm/atomic: Cleanup on error properly in the atomic ioctl."
cleaned up some error paths, but didn't fix the TEST_ONLY path.
In the check only case plane->fb shouldn't be updated, and
the vblank events should be cleared as on failure.

Changes since v1:
- Fix -EDEADLK handling of vblank events too.
- Free state last with CHECK_ONLY.
Changes since v2:
- Add comment about freeing crtc_state->event with TEST_ONLY.
  (Daniel Stone)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/drm_atomic.c

@@ -1515,7 +1515,8 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 			copied_props++;
 		}
 
-		if (obj->type == DRM_MODE_OBJECT_PLANE && count_props) {
+		if (obj->type == DRM_MODE_OBJECT_PLANE && count_props &&
+		    !(arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)) {
 			plane = obj_to_plane(obj);
 			plane_mask |= (1 << drm_plane_index(plane));
 			plane->old_fb = plane->fb;
@@ -1537,10 +1538,11 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	}
 
 	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
+		/*
+		 * Unlike commit, check_only does not clean up state.
+		 * Below we call drm_atomic_state_free for it.
+		 */
 		ret = drm_atomic_check_only(state);
-		/* _check_only() does not free state, unlike _commit() */
-		if (!ret)
-			drm_atomic_state_free(state);
 	} else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
 		ret = drm_atomic_async_commit(state);
 	} else {
@@ -1567,14 +1569,13 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 		plane->old_fb = NULL;
 	}
 
-	if (ret == -EDEADLK) {
-		drm_atomic_state_clear(state);
-		drm_modeset_backoff(&ctx);
-		goto retry;
-	}
+	if (ret && arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
+		/*
+		 * TEST_ONLY and PAGE_FLIP_EVENT are mutually exclusive,
+		 * if they weren't, this code should be called on success
+		 * for TEST_ONLY too.
+		 */
 
-	if (ret) {
-		if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
 		for_each_crtc_in_state(state, crtc, crtc_state, i) {
 			if (!crtc_state->event)
 				continue;
@@ -1584,9 +1585,15 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 		}
 	}
 
-		drm_atomic_state_free(state);
+	if (ret == -EDEADLK) {
+		drm_atomic_state_clear(state);
+		drm_modeset_backoff(&ctx);
+		goto retry;
 	}
 
+	if (ret || arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)
+		drm_atomic_state_free(state);
+
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);