Re: [dpdk-dev] [v3] net/i40e: fix vlan packets drop

[Thomas Monjalon <thomas@monjalon.net>]

08/11/2019 20:28, Kevin Traynor:
> Hi Xiao,
> 
> On 29/10/2019 05:12, Xiao Zhang wrote:
> > VLAN packets with ip length bigger than 1496 will not be received by
> > i40e/i40evf due to wrong packets size checking. This patch fixes the
> > issue by correcting the maximum frame size during checking.
> > 
> > Fixes: 43e5488c0ac6 ("net/i40e: support MTU configuration")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Xiao Zhang <xiao.zhang@intel.com>
> > ---
> > v3
> > Checking more places using max packet len.
> > v2
> > Add fix for i40evf and correct the checking when using the max_pkt_len.
> > ---
> >  drivers/net/i40e/i40e_ethdev.c    |  2 +-
> >  drivers/net/i40e/i40e_ethdev_vf.c | 11 +++++++----
> >  drivers/net/i40e/i40e_fdir.c      |  2 +-
> >  drivers/net/i40e/i40e_rxtx.c      |  9 ++++++---
> >  lib/librte_ethdev/rte_ethdev.c    | 10 ++++++++--
> >  lib/librte_net/rte_ether.h        |  1 +
> >  6 files changed, 24 insertions(+), 11 deletions(-)
> > 
> > --- a/lib/librte_ethdev/rte_ethdev.c
> > +++ b/lib/librte_ethdev/rte_ethdev.c
> > @@ -1257,11 +1257,17 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
> >  			goto rollback;
> >  		}
> >  	} else {
> > +		/**
> > +		 * The overhead from MTU to max frame size.
> > +		 * Considering VLAN and QinQ packet, the VLAN tag size
> > +		 * needs to be added to RTE_ETHER_MAX_LEN.
> > +		 */
> >  		if (dev_conf->rxmode.max_rx_pkt_len < RTE_ETHER_MIN_LEN ||
> > -			dev_conf->rxmode.max_rx_pkt_len > RTE_ETHER_MAX_LEN)
> > +			dev_conf->rxmode.max_rx_pkt_len > RTE_ETHER_MAX_LEN
> > +				+ RTE_ETHER_VLAN_LEN * 2)
> >  			/* Use default value */
> >  			dev->data->dev_conf.rxmode.max_rx_pkt_len =
> > -							RTE_ETHER_MAX_LEN;
> > +				RTE_ETHER_MAX_LEN + RTE_ETHER_VLAN_LEN * 2;
> 
> +cc ethdev maintainers
> 
> This looks ok to me for i40e case, but I don't know if there is a
> consequence for other PMDs. It seems late to change this, so maybe you
> can live without this part for now.
> 
> Even on the i40e parts, there can be some subtle bug and I requested
> i40e maintainers to review carefully but it has not happened, so for me
> it shouldn't be merged at present.

I would nack for another, simpler, reason:
No ethdev behaviour change should be submitted if title does not start
with "ethdev:" and if ethdev maintainers are not Cc'ed.