Re: [PATCH v3 6/8] net/vdev_netvsc: skip routed netvsc probing

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue,  9 Jan 2018 14:47:31 +0000
Matan Azrad <matan@mellanox.com> wrote:

> NetVSC netdevices which are already routed should not be probed because
> they are used for management purposes by the HyperV.
> 
> prevent routed netvsc devices probing.
> 
> Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  doc/guides/nics/vdev_netvsc.rst       |  2 +-
>  drivers/net/vdev_netvsc/vdev_netvsc.c | 46 +++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/nics/vdev_netvsc.rst b/doc/guides/nics/vdev_netvsc.rst
> index fde1fb8..f779862 100644
> --- a/doc/guides/nics/vdev_netvsc.rst
> +++ b/doc/guides/nics/vdev_netvsc.rst
> @@ -87,4 +87,4 @@ The following device parameters are supported:
>    MAC address.
>  
>  Not specifying either ``iface`` or ``mac`` makes this driver attach itself to
> -all NetVSC interfaces found on the system.
> +all unrouted NetVSC interfaces found on the system.
> diff --git a/drivers/net/vdev_netvsc/vdev_netvsc.c b/drivers/net/vdev_netvsc/vdev_netvsc.c
> index 3d8895b..4295b92 100644
> --- a/drivers/net/vdev_netvsc/vdev_netvsc.c
> +++ b/drivers/net/vdev_netvsc/vdev_netvsc.c
> @@ -38,6 +38,7 @@
>  #define VDEV_NETVSC_PROBE_MS 1000
>  
>  #define NETVSC_CLASS_ID "{f8615163-df3e-46c5-913f-f2d2f965ed0e}"
> +#define NETVSC_MAX_ROUTE_LINE_SIZE 300
>  
>  #define DRV_LOG(level, ...) \
>  	rte_log(RTE_LOG_ ## level, \
> @@ -192,6 +193,44 @@ static LIST_HEAD(, vdev_netvsc_ctx) vdev_netvsc_ctx_list =
>  }
>  
>  /**
> + * Determine if a network interface has a route.
> + *
> + * @param[in] name
> + *   Network device name.
> + *
> + * @return
> + *   A nonzero value when interface has an route. In case of error,
> + *   rte_errno is updated and 0 returned.
> + */
> +static int
> +vdev_netvsc_has_route(const char *name)
> +{
> +	FILE *fp;
> +	int ret = 0;
> +	char route[NETVSC_MAX_ROUTE_LINE_SIZE];
> +	char *netdev;
> +
> +	fp = fopen("/proc/net/route", "r");
> +	if (!fp) {
> +		rte_errno = errno;
> +		return 0;
> +	}
> +	while (fgets(route, NETVSC_MAX_ROUTE_LINE_SIZE, fp) != NULL) {
> +		netdev = strtok(route, "\t");
> +		if (strcmp(netdev, name) == 0) {
> +			ret = 1;
> +			break;
> +		}
> +		/* Move file pointer to the next line. */
> +		while (strchr(route, '\n') == NULL &&
> +		       fgets(route, NETVSC_MAX_ROUTE_LINE_SIZE, fp) != NULL)
> +			;
> +	}
> +	fclose(fp);
> +	return ret;
> +}

In many ways /proc/net/route is legacy intervace.
And system may have 1 M routes.

Maybe there is faster way to do this with netlink by looking to see if
there is an address associated with the interface.