Re: [PATCH 1/2] ixgb: Don't check for vlan group on transmit.

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

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On Fri, 2010-11-05 at 12:56 -0700, Jesse Gross wrote:
> On Fri, Nov 5, 2010 at 12:11 PM, Jeff Kirsher
> <jeffrey.t.kirsher@intel.com> wrote:
> > On Sat, 2010-10-30 at 11:49 -0700, Jesse Gross wrote:
> >> On transmit, the ixgb driver will only use vlan acceleration if a
> >> vlan group is configured.  This can lead to tags getting dropped
> >> when bridging because the networking core assumes that a driver
> >> that claims vlan acceleration support can do it at all times.  This
> >> change should have been part of commit eab6d18d "vlan: Don't check for
> >> vlan group before vlan_tx_tag_present." but was missed.
> >>
> >> Signed-off-by: Jesse Gross <jesse@nicira.com>
> >> CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> >> CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
> >> CC: PJ Waskiewicz <peter.p.waskiewicz.jr@intel.com>
> >> ---
> >>  drivers/net/ixgb/ixgb_main.c |    2 +-
> >>  1 files changed, 1 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c
> >> index caa8192..d18194e 100644
> >> --- a/drivers/net/ixgb/ixgb_main.c
> >> +++ b/drivers/net/ixgb/ixgb_main.c
> >> @@ -1498,7 +1498,7 @@ ixgb_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
> >>                       DESC_NEEDED)))
> >>               return NETDEV_TX_BUSY;
> >>
> >> -     if (adapter->vlgrp && vlan_tx_tag_present(skb)) {
> >> +     if (vlan_tx_tag_present(skb)) {
> >>               tx_flags |= IXGB_TX_FLAGS_VLAN;
> >>               vlan_id = vlan_tx_tag_get(skb);
> >>       }
> >
> > After further review, NAK because this will cause a bug.  With this
> > patch it would be possible to overrun the buffers, so the correct fix is
> > to increase max_frame_size by VLAN_TAG_SIZE in ixgb/igb_change_mtu.
> 
> Hmm, I didn't see any other place where it made changes to the
> handling of packets on transmit if a vlan group is configured.  Maybe
> the buffer is extended when a group is registered and stripping is
> enabled?
> 
> In any case, you might want to check the other Intel drivers for
> similar problems.  I did a pass and made a mass conversion of this
> type a little while ago.  Those changes have already been merged, I
> just missed this one by accident.

I will get with Alex and review the other Intel drivers, thanks Jesse.

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