Hi Fangzhi, kernel test robot noticed the following build warnings: https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Fangzhi-Zuo/drm-display-dsc-Refactor-MST-DSC-Determination-Policy/20240920-014114 base: git://anongit.freedesktop.org/drm-intel for-linux-next patch link: https://lore.kernel.org/r/20240919173944.256887-1-Jerry.Zuo%40amd.com patch subject: [PATCH] drm/display/dsc: Refactor MST DSC Determination Policy config: microblaze-randconfig-r071-20240922 (https://download.01.org/0day-ci/archive/20240923/202409231002.bMP89Ipm-lkp@xxxxxxxxx/config) compiler: microblaze-linux-gcc (GCC) 14.1.0 If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> | Closes: https://lore.kernel.org/r/202409231002.bMP89Ipm-lkp@xxxxxxxxx/ smatch warnings: drivers/gpu/drm/display/drm_dp_mst_topology.c:6046 drm_dp_mst_dsc_aux_for_port() warn: variable dereferenced before check 'port' (see line 6035) vim +/port +6046 drivers/gpu/drm/display/drm_dp_mst_topology.c cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6033 void drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port) c2bc1b6eabe65d drivers/gpu/drm/drm_dp_mst_topology.c David Francis 2019-08-26 6034 { cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 @6035 struct drm_dp_mst_topology_mgr *mgr = port->mgr; ^^^^^^^^^ The patch adds an unchecked dereference cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6036 struct drm_dp_mst_port *immediate_upstream_port = NULL; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6037 struct drm_dp_mst_port *fec_port = NULL; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6038 struct drm_dp_mst_port *dsc_port = NULL; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6039 struct drm_dp_aux *upstream_aux; 53965dbe5396d2 drivers/gpu/drm/drm_dp_mst_topology.c Paul E. McKenney 2020-02-19 6040 struct drm_dp_desc desc = {}; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6041 bool end_has_dpcd = (port->dpcd_rev > 0); cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6042 u8 endpoint_dsc = 0; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6043 u8 upstream_dsc; cc707186414576 drivers/gpu/drm/display/drm_dp_mst_topology.c Fangzhi Zuo 2024-09-19 6044 u8 fec_cap; c2bc1b6eabe65d drivers/gpu/drm/drm_dp_mst_topology.c David Francis 2019-08-26 6045 c2bc1b6eabe65d drivers/gpu/drm/drm_dp_mst_topology.c David Francis 2019-08-26 @6046 if (!port) ^^^^^ But the old code assumed port could be NULL. -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
