[PATCH v2 11/17] drm/display/dp_mst: Add helpers to query for payload allocation errors

[Imre Deak]

Hi,

On Thu, Feb 02, 2023 at 03:15:46PM +0300, Dan Carpenter wrote:
> Hi Imre,
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Imre-Deak/drm-i915-dp_mst-Add-the-MST-topology-state-for-modesetted-CRTCs/20230131-230853
> base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
> patch link:    https://lore.kernel.org/r/20230131150548.1614458-12-imre.deak%40intel.com
> patch subject: [PATCH v2 11/17] drm/display/dp_mst: Add helpers to query for payload allocation errors
> config: x86_64-randconfig-m001 (https://download.01.org/0day-ci/archive/20230202/202302021855.yyqIeQ2o-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp at intel.com>
> | Reported-by: Dan Carpenter <error27 at gmail.com>
> 
> smatch warnings:
> drivers/gpu/drm/display/drm_dp_mst_topology.c:3316 drm_dp_add_payload_part1() warn: missing error code 'ret'
> 
> vim +/ret +3316 drivers/gpu/drm/display/drm_dp_mst_topology.c
> 
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3304  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3305  			     struct drm_dp_mst_topology_state *mst_state,
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3306  			     struct drm_dp_mst_atomic_payload *payload)
> ad7f8a1f9ced7f drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-06-05  3307  {
> ad7f8a1f9ced7f drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-06-05  3308  	struct drm_dp_mst_port *port;
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3309  	int ret = 0;
> 706246c761ddd3 drivers/gpu/drm/drm_dp_mst_topology.c         Lyude Paul       2018-12-13  3310  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3311  	port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
> 33f960e23c29d1 drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2022-12-14  3312  	if (!port) {
> 33f960e23c29d1 drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2022-12-14  3313  		drm_dbg_kms(mgr->dev,
> 33f960e23c29d1 drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2022-12-14  3314  			    "VCPI %d for port %p not in topology, not creating a payload\n",
> 33f960e23c29d1 drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2022-12-14  3315  			    payload->vcpi, payload->port);
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31 @3316  		goto alloc_fail;
> 
> Hard to tell if this is an error path or a success path.

thanks for the report. The function before the change in this patchset
returned 0 in this case, so I didn't want to change that. Looking at the
callers none of them uses the return value (except for printing an error
message). I think returning an error code in this case as well would be
more consistent, but that change should be a follow-up.

> 33f960e23c29d1 drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2022-12-14  3317  	}
> cfe9f90358d97a drivers/gpu/drm/drm_dp_mst_topology.c         Lyude Paul       2019-01-10  3318  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3319  	if (mgr->payload_count == 0)
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3320  		mgr->next_start_slot = mst_state->start_slot;
> 3769e4c0af5b82 drivers/gpu/drm/drm_dp_mst_topology.c         Wayne Lin        2021-06-16  3321  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3322  	payload->vc_start_slot = mgr->next_start_slot;
> cfe9f90358d97a drivers/gpu/drm/drm_dp_mst_topology.c         Lyude Paul       2019-01-10  3323  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3324  	ret = drm_dp_create_payload_step1(mgr, payload);
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3325  	drm_dp_mst_topology_put_port(port);
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3326  	if (ret < 0) {
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3327  		drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3328  			 payload->port, ret);
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3329  		goto alloc_fail;
> ad7f8a1f9ced7f drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-06-05  3330  	}
> dfda0df3426483 drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-08-06  3331  
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3332  	payload->alloc_failed = false;
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3333  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3334  	mgr->payload_count++;
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3335  	mgr->next_start_slot += payload->time_slots;
> ad7f8a1f9ced7f drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-06-05  3336  
> 4d07b0bc403403 drivers/gpu/drm/display/drm_dp_mst_topology.c Lyude Paul       2022-08-17  3337  	return 0;
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3338  
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3339  alloc_fail:
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3340  	payload->vc_start_slot = -1;
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3341  	payload->alloc_failed = true;
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3342  
> 5c4df7ffba973b drivers/gpu/drm/display/drm_dp_mst_topology.c Imre Deak        2023-01-31  3343  	return ret;
> ad7f8a1f9ced7f drivers/gpu/drm/drm_dp_mst_topology.c         Dave Airlie      2014-06-05  3344  }
> 
> -- 
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