Subject: Re: [RFC PATCH] macvlan: add FDB bridge ops

From: John Fastabend <[email-masked]>
Date: Wed, 28 Mar 2012 08:58:49 -0700

On 3/28/2012 8:52 AM, Michael S. Tsirkin wrote:
> On Wed, Mar 28, 2012 at 08:43:56AM -0700, Roopa Prabhu wrote:
>> On 3/20/12 5:26 PM, "John Fastabend" <[email-masked]> wrote:
>>
>>> Add support to add/del and dump the forwarding database
>>> for macvlan passthru mode. The macvlan driver acts like
>>> a Two Port Mac Relay (TPMR 802.1Q-2011) in the passthru
>>> case so adding forwarding rules is just adding the addr
>>> to the uc or mc lists.
>>>
>>> By default the passthru mode puts the lowerdev into a
>>> promiscuous mode to receive all packets. This behavior
>>> is not changed by this patch. This is a bit problematic
>>> and needs to be solved without IMHO breaking existing
>>> mechanics. Maybe on the first add_fdb we can decrement
>>> the promisc mode? That seems to work reasonable well and
>>> keep existing functionality in place... but requires
>>> an initial add to set things up which is a bit annoying
>>> so maybe a flag is better. I haven't thought too hard
>>> about it yet so any ideas welcome
> 
> 
> ...
> 
>> Thanks John. Looks good.
>> I added a few things to your patch below. Yes, I think the promisc check is
>> required. Made an attempt to add a flag below (I did not get a chance to
>> think about other approaches there too). Briefly tested it with the br
>> command.
>>
>>
>> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
>> index f975afd..9bc70ad 100644
>> --- a/drivers/net/macvlan.c
>> +++ b/drivers/net/macvlan.c
>> @@ -34,6 +34,9 @@
>>  
>>  #define MACVLAN_HASH_SIZE    (1 << BITS_PER_BYTE)
>>  
>> +/* macvlan port flags */
>> +#define MACVLAN_FLAG_PROMISC    0x1
>> +
>>  struct macvlan_port {
>>      struct net_device    *dev;
>>      struct hlist_head    vlan_hash[MACVLAN_HASH_SIZE];
>> @@ -41,6 +44,7 @@ struct macvlan_port {
>>      struct rcu_head        rcu;
>>      bool             passthru;
>>      int            count;
>> +    unsigned int        flags;
>>  };
>>  
>>  static void macvlan_port_destroy(struct net_device *dev);
>> @@ -313,6 +317,7 @@ static int macvlan_open(struct net_device *dev)
>>  
>>      if (vlan->port->passthru) {
>>          dev_set_promiscuity(lowerdev, 1);
>> +        vlan->port->flags |= MACVLAN_FLAG_PROMISC;
>>          goto hash_add;
>>      }
>>  
>> @@ -345,10 +350,14 @@ static int macvlan_stop(struct net_device *dev)
>>      struct net_device *lowerdev = vlan->lowerdev;
>>  
>>      if (vlan->port->passthru) {
>> -        dev_set_promiscuity(lowerdev, -1);
>> +        if (vlan->port->flags & MACVLAN_FLAG_PROMISC) {
>> +            dev_set_promiscuity(lowerdev, -1);
>> +            vlan->port->flags &= ~MACVLAN_FLAG_PROMISC;
>> +        }
>>          goto hash_del;
>>      }
>>  
>> +    dev_uc_unsync(lowerdev, dev);
>>      dev_mc_unsync(lowerdev, dev);
>>      if (dev->flags & IFF_ALLMULTI)
>>          dev_set_allmulti(lowerdev, -1);
>> @@ -403,6 +412,7 @@ static void macvlan_set_multicast_list(struct net_device
>> *dev)
>>  {
>>      struct macvlan_dev *vlan = netdev_priv(dev);
>>  
>> +    dev_uc_sync(vlan->lowerdev, dev);
>>      dev_mc_sync(vlan->lowerdev, dev);
>>  }
>>  
>> @@ -542,6 +552,58 @@ static int macvlan_vlan_rx_kill_vid(struct net_device
>> *dev,
>>      return 0;
>>  }
>>  
>> +static int macvlan_fdb_add(struct ndmsg *ndm,
>> +               struct net_device *dev,
>> +               unsigned char *addr,
>> +               u16 flags)
>> +{
>> +    struct macvlan_dev *vlan = netdev_priv(dev);
>> +    struct net_device *lowerdev = vlan->lowerdev;
>> +    const struct net_device_ops *ops = lowerdev->netdev_ops;
>> +    int err = -EINVAL;
>> +
>> +    if (!vlan->port->passthru)
>> +        return -EOPNOTSUPP;
>> +
>> +    if (vlan->port->flags & MACVLAN_FLAG_PROMISC) {
>> +        dev_set_promiscuity (lowerdev, -1);
>> +        vlan->port->flags &= ~MACVLAN_FLAG_PROMISC;
>> +    }
>> +
>> +    if (ops->ndo_fdb_add)
>> +        return ops->ndo_fdb_add(ndm, lowerdev, addr, flags);
>> +
>> +    if (is_unicast_ether_addr(addr))
>> +        err = dev_uc_add_excl(lowerdev, addr);
>> +    else if (is_multicast_ether_addr(addr))
>> +        err = dev_mc_add(lowerdev, addr);
>> +
>> +    return err;
>> +}
>> +
>> +static int macvlan_fdb_del(struct ndmsg *ndm,
>> +               struct net_device *dev,
>> +               unsigned char *addr)
>> +{
>> +    struct macvlan_dev *vlan = netdev_priv(dev);
>> +    struct net_device *lowerdev = vlan->lowerdev;
>> +    const struct net_device_ops *ops = lowerdev->netdev_ops;
>> +    int err = -EINVAL;
>> +
>> +    if (!vlan->port->passthru)
>> +        return -EOPNOTSUPP;
>> +
>> +    if (ops->ndo_fdb_del)
>> +        return ops->ndo_fdb_del(ndm, lowerdev, addr);
>> +
>> +    if (is_unicast_ether_addr(addr))
>> +        err = dev_uc_del(lowerdev, addr);
>> +    else if (is_multicast_ether_addr(addr))
>> +        err = dev_mc_del(lowerdev, addr);
>> +
>> +    return err;
>> +}
>> +
>>  static void macvlan_ethtool_get_drvinfo(struct net_device *dev,
>>                      struct ethtool_drvinfo *drvinfo)
>>  {
>> @@ -577,6 +639,9 @@ static const struct net_device_ops macvlan_netdev_ops =
>> {
>>      .ndo_validate_addr    = eth_validate_addr,
>>      .ndo_vlan_rx_add_vid    = macvlan_vlan_rx_add_vid,
>>      .ndo_vlan_rx_kill_vid    = macvlan_vlan_rx_kill_vid,
>> +    .ndo_fdb_add        = macvlan_fdb_add,
>> +    .ndo_fdb_del        = macvlan_fdb_del,
>> +    .ndo_fdb_dump        = ndo_dflt_fdb_dump,
>>  };
>>  
>>  void macvlan_common_setup(struct net_device *dev)
>>
> 
> 
> So this clears the promisc on the first add which
> is a bit annoying. How about a simple flag, set when
> we create the macvlan?
> 

Agreed. This probably needs a new attrib maybe IFLA_MACVLAN_FLAGS unless
there already exists a per "kind" (rtnl_link_ops) flags field we can use.
I scanned the code briefly and didn't see any such thing so likely we need
the new attribute.

.John