drm/vblank: Register drmm cleanup action once per drm_vblank_crtc

Since we'll be allocating resources for kthread_create_worker() in the
next commit (which could fail and require us to clean up the mess),
let's simplify the cleanup process a bit by registering a
drm_vblank_init_release() action for each drm_vblank_crtc so they're
still cleaned up if we fail to initialize one of them.

Changes since v3:
* Use drmm_add_action_or_reset() - Daniel Vetter

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200627194657.156514-2-lyude@redhat.com

drivers/gpu/drm/drm_vblank.c

@@ -492,16 +492,12 @@ static void vblank_disable_fn(struct timer_list *t)
 
 static void drm_vblank_init_release(struct drm_device *dev, void *ptr)
 {
-	unsigned int pipe;
+	struct drm_vblank_crtc *vblank = ptr;
 
-	for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
-		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+	drm_WARN_ON(dev, READ_ONCE(vblank->enabled) &&
+		    drm_core_check_feature(dev, DRIVER_MODESET));
 
-		drm_WARN_ON(dev, READ_ONCE(vblank->enabled) &&
-			    drm_core_check_feature(dev, DRIVER_MODESET));
-
-		del_timer_sync(&vblank->disable_timer);
-	}
+	del_timer_sync(&vblank->disable_timer);
 }
 
 /**
@@ -511,7 +507,7 @@ static void drm_vblank_init_release(struct drm_device *dev, void *ptr)
  *
  * This function initializes vblank support for @num_crtcs display pipelines.
  * Cleanup is handled automatically through a cleanup function added with
- * drmm_add_action().
+ * drmm_add_action_or_reset().
  *
  * Returns:
  * Zero on success or a negative error code on failure.
@@ -530,10 +526,6 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
 
 	dev->num_crtcs = num_crtcs;
 
-	ret = drmm_add_action(dev, drm_vblank_init_release, NULL);
-	if (ret)
-		return ret;
-
 	for (i = 0; i < num_crtcs; i++) {
 		struct drm_vblank_crtc *vblank = &dev->vblank[i];
 
@@ -542,6 +534,11 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
 		init_waitqueue_head(&vblank->queue);
 		timer_setup(&vblank->disable_timer, vblank_disable_fn, 0);
 		seqlock_init(&vblank->seqlock);
+
+		ret = drmm_add_action_or_reset(dev, drm_vblank_init_release,
+					       vblank);
+		if (ret)
+			return ret;
 	}
 
 	return 0;