drm/i915: take struct mutex around fb unref

Need to do this in case the unref ends up doing a free.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 13f9b6667c94..4d2baf7b00be 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1606,7 +1606,9 @@ intel_user_framebuffer_create(struct drm_device *dev,
 
         ret = intel_framebuffer_create(dev, mode_cmd, &fb, obj);
         if (ret) {
+                mutex_lock(&dev->struct_mutex);
                 drm_gem_object_unreference(obj);
+                mutex_unlock(&dev->struct_mutex);
                 return NULL;
         }