netdev - RE: [net-next 08/12] ixgb: convert to new VLAN model

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Date:	Sun, 23 Jan 2011 17:25:15 -0700
From:	"Tantilov, Emil S" <emil.s.tantilov@...el.com>
To:	Jesse Gross <jesse@...ira.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"gosp@...hat.com" <gosp@...hat.com>,
	"bphilips@...ell.com" <bphilips@...ell.com>,
	"Pieper, Jeffrey E" <jeffrey.e.pieper@...el.com>
Subject: RE: [net-next 08/12] ixgb: convert to new VLAN model

Jesse Gross wrote:
> On Thu, Jan 6, 2011 at 7:29 PM,  <jeffrey.t.kirsher@...el.com> wrote:
>> +static int ixgb_set_flags(struct net_device *netdev, u32 data) +{
>> +       struct ixgb_adapter *adapter = netdev_priv(netdev); +      
>> bool need_reset; +       int rc;
>> +
>> +       /*
>> +        * TX vlan insertion does not work per HW design when Rx
>> stripping is +        * disabled.  Disable txvlan when rxvlan is
>> off. +        */ +       if ((data & ETH_FLAG_RXVLAN) !=
>> (netdev->features & NETIF_F_HW_VLAN_RX)) +               data ^=
>> ETH_FLAG_TXVLAN; 
> 
> Does this really do the right thing?  If the RX vlan setting is
> changed, it will do the opposite of what the user requested for TX
> vlan?
> 
> So if I start with both on (the default) and turn them both off in one
> command (a valid setting), I will get RX off and TX on (an invalid
> setting).
> 
> Why not:
> 
> if (!(data & ETH_FLAG_RXVLAN))
>         data &= ~ETH_FLAG_TXVLAN;

Yeah that works for disabling rxvlan, but what if rxvlan is disabled, and the user attempts to enable txvlan? At least our validation argued that we should make it work both ways. Perhaps something like the following?

	if (!(data & ETH_FLAG_RXVLAN) && 
	   (netdev->features & NETIF_F_HW_VLAN_TX))
		data &= ~ETH_FLAG_TXVLAN;
	else if (data & ETH_FLAG_TXVLAN)
		data |= ETH_FLAG_RXVLAN;

Thanks,
Emil--
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