[dpdk-dev] [PATCH] net/tap: add support for fixed mac addresses

[Pascal Mazon]

Hi Keith,

I have a few comments on your patch, see inline.

On Mon, 10 Apr 2017 13:18:50 -0500
Keith Wiles <keith.wiles at intel.com> wrote:

> Support for a fixed MAC address for testing with the last octet
> incrementing by one for each interface defined with the new 'mac=fixed'
> string on the --vdev option. The default option is still to randomize
> the MAC address for each tap interface.
> 
> Signed-off-by: Keith Wiles <keith.wiles at intel.com>
> ---
>  doc/guides/nics/tap.rst       | 13 +++++++++++-
>  drivers/net/tap/rte_eth_tap.c | 49 ++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 58 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst
> index 5c5ba5357..e3819836a 100644
> --- a/doc/guides/nics/tap.rst
> +++ b/doc/guides/nics/tap.rst
> @@ -46,7 +46,7 @@ These TAP interfaces can be used with Wireshark or tcpdump or Pktgen-DPDK
>  along with being able to be used as a network connection to the DPDK
>  application. The method enable one or more interfaces is to use the
>  ``--vdev=net_tap0`` option on the DPDK application command line. Each
> -``--vdev=net_tap1`` option give will create an interface named dtap0, dtap1,
> +``--vdev=net_tap1`` option given will create an interface named dtap0, dtap1,
>  and so on.
>  
>  The interface name can be changed by adding the ``iface=foo0``, for example::
> @@ -58,6 +58,17 @@ needed, but the interface does not enforce that speed, for example::
>  
>     --vdev=net_tap0,iface=foo0,speed=25000
>  
> +Normally the PMD will generate random MAC address, but when testing or with

"random MAC" -> "a random MAC"

> +a static configurations the developer may need a fixed MAC address style.

"configurations" -> "configuration"

> +Using the option ``mac=fixed`` you can create a fixed known MAC address::
> +
> +   --vdev=net_tap0,mac=fixed
> +
> +The MAC address will be fixed value with the last octet incrementing by one

"be" -> "have a"

> +each time for each interface string containing ``mac=fixed``. The MAC address

"each time" -> ""

> +is formatted as 00:'d':'t':'a':'p':[00-FF] convert the characters to hex

" convert" -> ". Convert"

> +and you get ``00:64:74:61:70:[00-FF]``.
> +
>  It is possible to specify a remote netdevice to capture packets from by adding
>  ``remote=foo1``, for example::
>  
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index 347a80741..7a676c588 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -1,7 +1,7 @@
>  /*-
>   *   BSD LICENSE
>   *
> - *   Copyright(c) 2016 Intel Corporation. All rights reserved.
> + *   Copyright(c) 2017 Intel Corporation. All rights reserved.

Shouldn't it be "2016-2017"?

>   *   All rights reserved.
>   *
>   *   Redistribution and use in source and binary forms, with or without
> @@ -71,6 +71,13 @@
>  #define ETH_TAP_IFACE_ARG       "iface"
>  #define ETH_TAP_SPEED_ARG       "speed"
>  #define ETH_TAP_REMOTE_ARG      "remote"
> +#define ETH_TAP_MAC_ARG		"mac"

You used tabs instead of spaces.

> +
> +#ifdef IFF_MULTI_QUEUE
> +#define RTE_PMD_TAP_MAX_QUEUES	16
> +#else
> +#define RTE_PMD_TAP_MAX_QUEUES	1
> +#endif

Remove this IFF_MULTI_QUEUE definition as it is done in rte_eth_tap.h now (needed for pmd_internals).

>  
>  #define FLOWER_KERNEL_VERSION KERNEL_VERSION(4, 2, 0)
>  #define FLOWER_VLAN_KERNEL_VERSION KERNEL_VERSION(4, 9, 0)
> @@ -81,10 +88,12 @@ static const char *valid_arguments[] = {
>  	ETH_TAP_IFACE_ARG,
>  	ETH_TAP_SPEED_ARG,
>  	ETH_TAP_REMOTE_ARG,
> +	ETH_TAP_MAC_ARG,
>  	NULL
>  };
>  
>  static int tap_unit;
> +static int fixed_mac_type;

There is no need for a global variable, especially as the value should not be the same for each driver instance.
Typically when one tap uses "mac=fixed" and the next one doesn't.
More comments bellow for that.

>  
>  static volatile uint32_t tap_trigger;	/* Rx trigger */
>  
> @@ -1230,7 +1239,17 @@ eth_dev_tap_create(const char *name, char *tap_name, char *remote_iface)
>  		rte_memcpy(&pmd->eth_addr, ifr.ifr_hwaddr.sa_data,
>  			   ETHER_ADDR_LEN);
>  	} else {
> -		eth_random_addr((uint8_t *)&pmd->eth_addr);
> +		if (fixed_mac_type) {
> +			static int iface_idx;
> +
> +			pmd->eth_addr.addr_bytes[0] = 0x00;
> +			pmd->eth_addr.addr_bytes[1] = 'd';
> +			pmd->eth_addr.addr_bytes[2] = 't';
> +			pmd->eth_addr.addr_bytes[3] = 'a';
> +			pmd->eth_addr.addr_bytes[4] = 'p';
> +			pmd->eth_addr.addr_bytes[5] = 0 + iface_idx++;
> +		} else
> +			eth_random_addr((uint8_t *)&pmd->eth_addr);

To avoid checkpatch warning, use else { }.

>  	}
>  
>  	return 0;
> @@ -1285,6 +1304,16 @@ set_remote_iface(const char *key __rte_unused,
>  	return 0;
>  }
>  
> +static int
> +set_mac_type(const char *key __rte_unused, const char *value, void *extra_args)
> +{
> +	/* Assume random mac address */
> +	*(int *)extra_args = 0;

With an automatic variable for fixed_mac_type in rte_pmd_tap_probe(), no need for setting it to 0 here.

> +	if (value && !strcasecmp("fixed", value))

I think a macro for "fixed" would be better. Maybe a ETH_TAP_MAC_FIXED "fixed" at the top?

> +		*(int *)extra_args = 1;
> +	return 0;
> +}
> +
>  /* Open a TAP interface device.
>   */
>  static int
> @@ -1301,6 +1330,7 @@ rte_pmd_tap_probe(const char *name, const char *params)
>  		 DEFAULT_TAP_NAME, tap_unit++);
>  	memset(remote_iface, 0, RTE_ETH_NAME_MAX_LEN);
>  
> +	fixed_mac_type = 0;

Turn fixed_mac_type to an automatic variable, local to this function.
And add the argument to eth_dev_tap_create().

>  	if (params && (params[0] != '\0')) {
>  		RTE_LOG(DEBUG, PMD, "paramaters (%s)\n", params);
>  
> @@ -1332,6 +1362,15 @@ rte_pmd_tap_probe(const char *name, const char *params)
>  				if (ret == -1)
>  					goto leave;
>  			}
> +
> +			if (rte_kvargs_count(kvlist, ETH_TAP_MAC_ARG) == 1) {
> +				ret = rte_kvargs_process(kvlist,
> +							 ETH_TAP_MAC_ARG,
> +							 &set_mac_type,
> +							 &fixed_mac_type);
> +				if (ret == -1)
> +					goto leave;
> +			}
>  		}
>  	}
>  	pmd_link.link_speed = speed;
> @@ -1394,4 +1433,8 @@ static struct rte_vdev_driver pmd_tap_drv = {
>  };
>  RTE_PMD_REGISTER_VDEV(net_tap, pmd_tap_drv);
>  RTE_PMD_REGISTER_ALIAS(net_tap, eth_tap);
> -RTE_PMD_REGISTER_PARAM_STRING(net_tap, "iface=<string>,speed=N");
> +RTE_PMD_REGISTER_PARAM_STRING(net_tap,
> +			      "iface=<string>,"
> +			      "speed=N,"
> +			      "remote=<string>,"
> +			      "mac=fixed");

Indeed, I forgot to update that when I introduced the remote!

That's it for me,
Thank you.

Pascal