[PATCH] net/mlx5: fix interface name parameter definition

[Etelson, Gregory]

Hello Stephen,

>> The patch fixes `ifname` parameter as a character buffer.
>>
>> Fixes: 1256805dd54d ("net/mlx5: move Linux-specific functions")
>>
>> Signed-off-by: Gregory Etelson <getelson at nvidia.com>
>> Acked-by: Dariusz Sosnowski <dsosnowski at nvidia.com>
>> ---
>
> This looks better but did you know that the ifname can never be as big as MLX5_NAMESIZE.
> Kernel limits to IFNAMSIZ (ie 16). The largest allowable interface name in Linux is 15 characters.
>
> Looks like:
>        MLX5_NAMESIZE := MXL5_FS_NAME_MAX := IBV_SYSFS_NAME_MAX + 1 = 64 + 1 = 65
>
> Because Linux interface name length is fixed by BSD legacy ABI's it will never be longer.
>

The MLX5 PMD defines MLX5_NAMESIZE macro for Linux and Windows.

The Linux definition is in the drivers/net/mlx5/linux/mlx5_os.h:
#define MLX5_NAMESIZE IF_NAMESIZE

Linux API sets IF_NAMESIZE to 16.

The Windows definition is in the drivers/net/mlx5/windows/mlx5_os.h:
#define MLX5_NAMESIZE MLX5_FS_NAME_MAX.

The MLX5_FS_NAME_MAX macro also has different definitions for Linux and Windows:

drivers/common/mlx5/linux/mlx5_common_os.h
MLX5_FS_NAME_MAX = IBV_SYSFS_NAME_MAX + 1

IB verbs API sets IBV_SYSFS_NAME_MAX to 265.

drivers/common/mlx5/windows/mlx5_common_os.h: 
MLX5_FS_NAME_MAX = MLX5_DEVX_DEVICE_NAME_SIZE + 1

MLX5_DEVX_DEVICE_NAME_SIZE is defined by NVIDIA/Mellanox’s DevX (WinOF2) 
user-space headers for Windows and is set to 64.

Regards,
Gregory