[bug report] net/mlx5: E-switch, Allow setting share/max tx rate limits of rate groups

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Dmytro Linkin,

The patch f47e04eb96e0: "net/mlx5: E-switch, Allow setting share/max
tx rate limits of rate groups" from May 31, 2021, leads to the
following Smatch static checker warning:

	drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c:483 esw_qos_create_rate_group()
	warn: passing zero to 'ERR_PTR'

drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c
    434 static struct mlx5_esw_rate_group *
    435 esw_qos_create_rate_group(struct mlx5_eswitch *esw, struct netlink_ext_ack *extack)
    436 {
    437 	u32 tsar_ctx[MLX5_ST_SZ_DW(scheduling_context)] = {};
    438 	struct mlx5_esw_rate_group *group;
    439 	u32 divider;
    440 	int err;
    441 
    442 	if (!MLX5_CAP_QOS(esw->dev, log_esw_max_sched_depth))
    443 		return ERR_PTR(-EOPNOTSUPP);
    444 
    445 	group = kzalloc(sizeof(*group), GFP_KERNEL);
    446 	if (!group)
    447 		return ERR_PTR(-ENOMEM);
    448 
    449 	MLX5_SET(scheduling_context, tsar_ctx, parent_element_id,
    450 		 esw->qos.root_tsar_ix);
    451 	err = mlx5_create_scheduling_element_cmd(esw->dev,
    452 						 SCHEDULING_HIERARCHY_E_SWITCH,
    453 						 tsar_ctx,
    454 						 &group->tsar_ix);
    455 	if (err) {
    456 		NL_SET_ERR_MSG_MOD(extack, "E-Switch create TSAR for group failed");
    457 		goto err_sched_elem;
    458 	}
    459 
    460 	list_add_tail(&group->list, &esw->qos.groups);
    461 
    462 	divider = esw_qos_calculate_min_rate_divider(esw, group, true);
    463 	if (divider) {
    464 		err = esw_qos_normalize_groups_min_rate(esw, divider, extack);
    465 		if (err) {
    466 			NL_SET_ERR_MSG_MOD(extack, "E-Switch groups normalization failed");
    467 			goto err_min_rate;

Wouldn't we want to we want to propagate this error code


    468 		}
    469 	}
    470 	trace_mlx5_esw_group_qos_create(esw->dev, group, group->tsar_ix);
    471 
    472 	return group;
    473 
    474 err_min_rate:
    475 	list_del(&group->list);
    476 	err = mlx5_destroy_scheduling_element_cmd(esw->dev,
    477 						  SCHEDULING_HIERARCHY_E_SWITCH,
    478 						  group->tsar_ix);

instead of this one?  Also if this succeeds we return succeess?

    479 	if (err)
    480 		NL_SET_ERR_MSG_MOD(extack, "E-Switch destroy TSAR for group failed");
    481 err_sched_elem:
    482 	kfree(group);
--> 483 	return ERR_PTR(err);
    484 }

regards,
dan carpenter