drm: Move drm_mode_setcrtc() local re-init to failure path

Instead of always re-initializing the variables we need to clean up on
out, move the re-initialization into the branch that goes back to retry
label.

This is a lateral move right now, but will allow us to pull out the
modeset locking into common code. I kept this change separate to make
things easier to review.

Changes in v2:
- None

Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181129150423.239081-2-sean@poorly.run

drivers/gpu/drm/drm_crtc.c

@@ -570,9 +570,9 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 	struct drm_mode_crtc *crtc_req = data;
 	struct drm_crtc *crtc;
 	struct drm_plane *plane;
-	struct drm_connector **connector_set, *connector;
-	struct drm_framebuffer *fb;
-	struct drm_display_mode *mode;
+	struct drm_connector **connector_set = NULL, *connector;
+	struct drm_framebuffer *fb = NULL;
+	struct drm_display_mode *mode = NULL;
 	struct drm_mode_set set;
 	uint32_t __user *set_connectors_ptr;
 	struct drm_modeset_acquire_ctx ctx;
@@ -601,10 +601,6 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 	mutex_lock(&crtc->dev->mode_config.mutex);
 	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
 retry:
-	connector_set = NULL;
-	fb = NULL;
-	mode = NULL;
-
 	ret = drm_modeset_lock_all_ctx(crtc->dev, &ctx);
 	if (ret)
 		goto out;
@@ -766,6 +762,12 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 	}
 	kfree(connector_set);
 	drm_mode_destroy(dev, mode);
+
+	/* In case we need to retry... */
+	connector_set = NULL;
+	fb = NULL;
+	mode = NULL;
+
 	if (ret == -EDEADLK) {
 		ret = drm_modeset_backoff(&ctx);
 		if (!ret)