[1/2] drm: Return EBUSY if the framebuffer is unbound when flipping.

Commit Message

Chris Wilson July 17, 2010, 7:23 p.m. UTC

None

Patch

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 0371a2f..d9d5e9f 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -2610,6 +2610,15 @@  int drm_mode_page_flip_ioctl(struct drm_device *dev,
 		goto out;
 	crtc = obj_to_crtc(obj);
 
+	if (crtc->fb == NULL) {
+		/* The framebuffer is currently unbound, presumably
+		 * due to a hotplug event, that userspace has not
+		 * yet discovered.
+		 */
+		ret = -EBUSY;
+		goto out;
+	}
+
 	if (crtc->funcs->page_flip == NULL)
 		goto out;