drm: Add locking around cursor gem operations.

We need to hold the struct_mutex around pinning and the phys object
operations.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/intel_display.c

@@ -1043,18 +1043,19 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 	}
 
 	/* we only need to pin inside GTT if cursor is non-phy */
+	mutex_lock(&dev->struct_mutex);
 	if (!dev_priv->cursor_needs_physical) {
 		ret = i915_gem_object_pin(bo, PAGE_SIZE);
 		if (ret) {
 			DRM_ERROR("failed to pin cursor bo\n");
-			goto fail;
+			goto fail_locked;
 		}
 		addr = obj_priv->gtt_offset;
 	} else {
 		ret = i915_gem_attach_phys_object(dev, bo, (pipe == 0) ? I915_GEM_PHYS_CURSOR_0 : I915_GEM_PHYS_CURSOR_1);
 		if (ret) {
 			DRM_ERROR("failed to attach phys object\n");
-			goto fail;
+			goto fail_locked;
 		}
 		addr = obj_priv->phys_obj->handle->busaddr;
 	}
@@ -1074,17 +1075,17 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 				i915_gem_detach_phys_object(dev, intel_crtc->cursor_bo);
 		} else
 			i915_gem_object_unpin(intel_crtc->cursor_bo);
-		mutex_lock(&dev->struct_mutex);
 		drm_gem_object_unreference(intel_crtc->cursor_bo);
-		mutex_unlock(&dev->struct_mutex);
 	}
+	mutex_unlock(&dev->struct_mutex);
 
 	intel_crtc->cursor_addr = addr;
 	intel_crtc->cursor_bo = bo;
 
 	return 0;
 fail:
 	mutex_lock(&dev->struct_mutex);
+fail_locked:
 	drm_gem_object_unreference(bo);
 	mutex_unlock(&dev->struct_mutex);
 	return ret;