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

[Vlad Dumitrescu <vdumitrescu@nvidia.com>]

On 9/12/25 05:47, Dan Carpenter wrote:
> 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 }

Dan, thank you for the report!

Saeed, it seems like this was introduced all the way back in v2.

Vlad