---

yaml
---
r: 358354
b: refs/heads/master
c: 8cf1e98
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c976cb37a95a8dcaf23d04d6487fbacc33d3c913
+refs/heads/master: 8cf1e9811471f2910fa38dc1b28e1789080ba961

trunk/Documentation/DocBook/drm.tmpl

@@ -1160,6 +1160,12 @@ int max_width, max_height;</synopsis>
             without waiting for rendering or page flip to complete and must block
             any new rendering to the frame buffer until the page flip completes.
           </para>
+          <para>
+            If a page flip can be successfully scheduled the driver must set the
+            <code>drm_crtc-&lt;fb</code> field to the new framebuffer pointed to
+            by <code>fb</code>. This is important so that the reference counting
+            on framebuffers stays balanced.
+          </para>
           <para>
             If a page flip is already pending, the
             <methodname>page_flip</methodname> operation must return

trunk/drivers/gpu/drm/drm_crtc.c

@@ -3792,6 +3792,13 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
 		/* Keep the old fb, don't unref it. */
 		old_fb = NULL;
 	} else {
+		/*
+		 * Warn if the driver hasn't properly updated the crtc->fb
+		 * field to reflect that the new framebuffer is now used.
+		 * Failing to do so will screw with the reference counting
+		 * on framebuffers.
+		 */
+		WARN_ON(crtc->fb != fb);
 		/* Unref only the old framebuffer. */
 		fb = NULL;
 	}