netdev - Re: [PATCH v2 10/14] ixgbe: Update ixgbe to use new vlan accleration.

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Date:	Mon, 25 Oct 2010 10:50:09 -0700
From:	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
To:	Michał Mirosław <mirqus@...il.com>
Cc:	Jesse Gross <jesse@...ira.com>, David Miller <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Tantilov, Emil S" <emil.s.tantilov@...el.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
Subject: Re: [PATCH v2 10/14] ixgbe: Update ixgbe to use new vlan
 accleration.

On Fri, 2010-10-22 at 06:24 -0700, Michał Mirosław wrote:
> 2010/10/21 Jesse Gross <jesse@...ira.com>:
> > Make the ixgbe driver use the new vlan accleration model.
> [...]
> > --- a/drivers/net/ixgbe/ixgbe_main.c
> > +++ b/drivers/net/ixgbe/ixgbe_main.c
> > @@ -954,17 +954,13 @@ static void ixgbe_receive_skb(struct ixgbe_q_vector *q_vector,
> >        bool is_vlan = (status & IXGBE_RXD_STAT_VP);
> >        u16 tag = le16_to_cpu(rx_desc->wb.upper.vlan);
> >
> > -       if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL)) {
> > -               if (adapter->vlgrp && is_vlan && (tag & VLAN_VID_MASK))
> > -                       vlan_gro_receive(napi, adapter->vlgrp, tag, skb);
> > -               else
> > -                       napi_gro_receive(napi, skb);
> > -       } else {
> > -               if (adapter->vlgrp && is_vlan && (tag & VLAN_VID_MASK))
> > -                       vlan_hwaccel_rx(skb, adapter->vlgrp, tag);
> > -               else
> > -                       netif_rx(skb);
> > -       }
> > +       if (is_vlan && (tag & VLAN_VID_MASK))
> > +               __vlan_hwaccel_put_tag(skb, tag);
> 
> I know that this is carried over from the driver, but why tag == 0 is
> treated differently here? VID0 is somewhat special, as normally it
> means 802.1p packet, but i.e. in embedded world people are using it as
> normal VID. It would be nice to have this handled consistently in the
> VLAN core - deliver to base dev (tag stripped) if vlan 0 is not
> configured and to vlan dev if it is.

ixgbe handles VLAN 0 differently because that's the tag that's used when
DCB is enabled, and no VLAN is configured.  We have to insert the 802.1p
tag for DCB to work, but the OS won't know about the 802.1q tag, and
ends up dropping the frame.  So we enable VLAN ID 0 in the HW and tell
it to strip the tag, so we can still pass the frame up the stack.

> 
> > +
> > +       if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
> > +               napi_gro_receive(napi, skb);
> > +       else
> > +               netif_rx(skb);
> >  }
> >
> >  /**
> 
> Best Regards,
> Michał Mirosław

-- 
-----------------------------------------------------------
Peter P Waskiewicz Jr                   LAN Access Division
peter.p.waskiewicz.jr@...el.com         Intel Corp.

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