[bug report] net/mlx5: Implement devlink total_vfs parameter

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello Vlad Dumitrescu,

Commit a4c49611cf4f ("net/mlx5: Implement devlink total_vfs
parameter") from Sep 6, 2025 (linux-next), leads to the following
Smatch static checker warning:

	drivers/net/ethernet/mellanox/mlx5/core/lib/nv_param.c:494 mlx5_devlink_total_vfs_set()
	warn: duplicate check 'per_pf_support' (previous on line 479)

drivers/net/ethernet/mellanox/mlx5/core/lib/nv_param.c
    455 static int mlx5_devlink_total_vfs_set(struct devlink *devlink, u32 id,
    456                                       struct devlink_param_gset_ctx *ctx,
    457                                       struct netlink_ext_ack *extack)
    458 {
    459         struct mlx5_core_dev *dev = devlink_priv(devlink);
    460         u32 mnvda[MLX5_ST_SZ_DW(mnvda_reg)];
    461         bool per_pf_support;
    462         void *data;
    463         int err;
    464 
    465         err = mlx5_nv_param_read_global_pci_cap(dev, mnvda, sizeof(mnvda));
    466         if (err) {
    467                 NL_SET_ERR_MSG_MOD(extack, "Failed to read global pci cap");
    468                 return err;
    469         }
    470 
    471         data = MLX5_ADDR_OF(mnvda_reg, mnvda, configuration_item_data);
    472         if (!MLX5_GET(nv_global_pci_cap, data, sriov_support)) {
    473                 NL_SET_ERR_MSG_MOD(extack, "Not configurable on this device");
    474                 return -EOPNOTSUPP;
    475         }
    476 
    477         per_pf_support = MLX5_GET(nv_global_pci_cap, data,
    478                                   per_pf_total_vf_supported);
    479         if (!per_pf_support) {
    480                 /* We don't allow global SRIOV setting on per PF devlink */
    481                 NL_SET_ERR_MSG_MOD(extack,
    482                                    "SRIOV is not per PF on this device");
    483                 return -EOPNOTSUPP;

!per_pf_support is not supported.

    484         }
    485 
    486         memset(mnvda, 0, sizeof(mnvda));
    487         err = mlx5_nv_param_read_global_pci_conf(dev, mnvda, sizeof(mnvda));
    488         if (err)
    489                 return err;
    490 
    491         MLX5_SET(nv_global_pci_conf, data, sriov_valid, 1);
    492         MLX5_SET(nv_global_pci_conf, data, per_pf_total_vf, per_pf_support);
    493 
--> 494         if (!per_pf_support) {
    495                 MLX5_SET(nv_global_pci_conf, data, total_vfs, ctx->val.vu32);
    496                 return mlx5_nv_param_write(dev, mnvda, sizeof(mnvda));

Dead code.

    497         }
    498 
    499         /* SRIOV is per PF */
    500         err = mlx5_nv_param_write(dev, mnvda, sizeof(mnvda));
    501         if (err)
    502                 return err;
    503 
    504         memset(mnvda, 0, sizeof(mnvda));
    505         err = mlx5_nv_param_read_per_host_pf_conf(dev, mnvda, sizeof(mnvda));
    506         if (err)
    507                 return err;
    508 
    509         data = MLX5_ADDR_OF(mnvda_reg, mnvda, configuration_item_data);
    510         MLX5_SET(nv_pf_pci_conf, data, total_vf, ctx->val.vu32);
    511         return mlx5_nv_param_write(dev, mnvda, sizeof(mnvda));
    512 }

regards,
dan carpenter