Re: [PATCH 4/6] net/tap: add MTU management

[Pascal Mazon <pascal.mazon@6wind.com>]

On Fri, 3 Mar 2017 15:23:28 +0000
"Wiles, Keith" <keith.wiles@intel.com> wrote:

> 
> > On Mar 3, 2017, at 3:46 AM, Pascal Mazon <pascal.mazon@6wind.com>
> > wrote:
> > 
> > The MTU is assigned to the tap netdevice according to the argument,
> > but packet transmission and reception just write/read on an fd with
> > the default limit being the socket buffer size.
> > 
> > Signed-off-by: Pascal Mazon <pascal.mazon@6wind.com>
> > ---
> > doc/guides/nics/features/tap.ini |  1 +
> > drivers/net/tap/rte_eth_tap.c    | 37
> > +++++++++++++++++++++++++++++++++++++ 2 files changed, 38
> > insertions(+)
> > 
> > diff --git a/doc/guides/nics/features/tap.ini
> > b/doc/guides/nics/features/tap.ini index 6878a9b8fd17..6aa11874e2bc
> > 100644 --- a/doc/guides/nics/features/tap.ini
> > +++ b/doc/guides/nics/features/tap.ini
> > @@ -9,6 +9,7 @@ Jumbo frame          = Y
> > Promiscuous mode     = Y
> > Allmulticast mode    = Y
> > Basic stats          = Y
> > +MTU update           = Y
> > Multicast MAC filter = Y
> > Speed capabilities   = Y
> > Unicast MAC filter   = Y
> > diff --git a/drivers/net/tap/rte_eth_tap.c
> > b/drivers/net/tap/rte_eth_tap.c index 131c09fbc1a5..64b84cd76321
> > 100644 --- a/drivers/net/tap/rte_eth_tap.c
> > +++ b/drivers/net/tap/rte_eth_tap.c
> > @@ -724,6 +724,42 @@ tap_set_mc_addr_list(struct rte_eth_dev *dev
> > __rte_unused, return 0;
> > }
> > 
> > +static int
> > +tap_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> > +{
> > +	struct pmd_internals *pmd = dev->data->dev_private;
> > +	struct ifreq ifr;
> > +	int err, s;
> > +
> > +	s = socket(AF_INET, SOCK_DGRAM, 0);
> > +	if (s < 0) {
> > +		RTE_LOG(ERR, PMD,
> > +			"Unable to get a socket for %s to set
> > flags: %s\n",
> > +			pmd->name, strerror(errno));
> > +		return -1;
> > +	}
> > +	memset(&ifr, 0, sizeof(ifr));
> > +	strncpy(ifr.ifr_name, pmd->name, IFNAMSIZ);
> 
> This needs to be converted to a snprintf() to avoid overflow.
> 

Ok, I'll do that in version 2.

Regards,
Pascal

> > +	err = ioctl(s, SIOCGIFMTU, &ifr);
> > +	if (err < 0) {
> > +		RTE_LOG(WARNING, PMD, "Unable to get %s device
> > MTU: %s\n",
> > +			pmd->name, strerror(errno));
> > +		close(s);
> > +		return -1;
> > +	}
> > +	ifr.ifr_mtu = mtu;
> > +	err = ioctl(s, SIOCSIFMTU, &ifr);
> > +	if (err < 0) {
> > +		RTE_LOG(WARNING, PMD, "Unable to set %s mtu %d:
> > %s\n",
> > +			pmd->name, mtu, strerror(errno));
> > +		close(s);
> > +		return -1;
> > +	}
> > +	close(s);
> > +	dev->data->mtu = mtu;
> > +	return 0;
> > +}
> > +
> > static const struct eth_dev_ops ops = {
> > 	.dev_start              = tap_dev_start,
> > 	.dev_stop               = tap_dev_stop,
> > @@ -745,6 +781,7 @@ static const struct eth_dev_ops ops = {
> > 	.mac_addr_add           = tap_mac_add,
> > 	.mac_addr_set           = tap_mac_set,
> > 	.set_mc_addr_list       = tap_set_mc_addr_list,
> > +	.mtu_set                = tap_mtu_set,
> > 	.stats_get              = tap_stats_get,
> > 	.stats_reset            = tap_stats_reset,
> > };
> > -- 
> > 2.8.0.rc0
> > 
> 
> Regards,
> Keith
>