netdev - Re: [PATCH net] vmxnet3: Don't enable vlan filters in promiscuous mode.

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Date:	Wed, 10 Aug 2011 08:16:20 +0800
From:	Jesse Gross <jesse@...ira.com>
To:	Shreyas Bhatewara <sbhatewara@...are.com>
Cc:	David Miller <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Scott Goldman <scottjg@...are.com>,
	VMware PV-Drivers <pv-drivers@...are.com>
Subject: Re: [PATCH net] vmxnet3: Don't enable vlan filters in promiscuous mode.

On Wed, Aug 10, 2011 at 5:32 AM, Shreyas Bhatewara
<sbhatewara@...are.com> wrote:
>
>
> On Mon, 8 Aug 2011, Jesse Gross wrote:
>
>> @@ -1929,14 +1929,17 @@ static void
>>  vmxnet3_vlan_rx_add_vid(struct net_device *netdev, u16 vid)
>>  {
>>       struct vmxnet3_adapter *adapter = netdev_priv(netdev);
>> -     u32 *vfTable = adapter->shared->devRead.rxFilterConf.vfTable;
>> -     unsigned long flags;
>>
>> -     VMXNET3_SET_VFTABLE_ENTRY(vfTable, vid);
>> -     spin_lock_irqsave(&adapter->cmd_lock, flags);
>> -     VMXNET3_WRITE_BAR1_REG(adapter, VMXNET3_REG_CMD,
>> -                            VMXNET3_CMD_UPDATE_VLAN_FILTERS);
>> -     spin_unlock_irqrestore(&adapter->cmd_lock, flags);
>> +     if (!(netdev->flags & IFF_PROMISC)) {
>> +             u32 *vfTable = adapter->shared->devRead.rxFilterConf.vfTable;
>> +             unsigned long flags;
>> +
>> +             VMXNET3_SET_VFTABLE_ENTRY(vfTable, vid);
>> +             spin_lock_irqsave(&adapter->cmd_lock, flags);
>> +             VMXNET3_WRITE_BAR1_REG(adapter, VMXNET3_REG_CMD,
>> +                                    VMXNET3_CMD_UPDATE_VLAN_FILTERS);
>> +             spin_unlock_irqrestore(&adapter->cmd_lock, flags);
>> +     }
>>
>
> If this is done, the driver will ignore all vlan tag registrations (and
> deletions) while the interface is in promiscuous mode. Better solution
> would be to send UPDATE_VLAN_FILTERS command alone inside the promiscuous
> condition. vfTable can be set/unset unconditionally as before. By doing
> this, when the interface comes out of promiscuous mode, the restored vlan
> state will have all the added/removed vlan tags into effect.

Adds and removes are not ignored when in promiscuous mode because the
active_vlans bitfield is still being updated (this is in the context
that you clipped out).  When we come out of promiscuous mode,
vmxnet3_restore_vlan() is called which will update the hardware with
the vlans that have been registered.  This is much safer than directly
updating vfTable because it will get overwritten if vmxnet3_set_mc()
is called again and is potentially very error prone to have it not
reflect what we actually want programmed in the hardware.
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