Subject: Re: [PATCH net-next RFC v2] switchdev: bridge: drop hardware forwarded packets

From: roopa <[email-masked]>
Date: Tue, 24 Mar 2015 10:45:03 -0700

On 3/24/15, 9:01 AM, Guenter Roeck wrote:
> On Tue, Mar 24, 2015 at 03:29:21PM +0100, Jiri Pirko wrote:
>>> diff --git a/drivers/net/ethernet/rocker/rocker.c
>>> b/drivers/net/ethernet/rocker/rocker.c
>>> index aab962c..0f7217f7 100644
>>> --- a/drivers/net/ethernet/rocker/rocker.c
>>> +++ b/drivers/net/ethernet/rocker/rocker.c
>>> @@ -3931,15 +3931,28 @@ unmap_frag:
>>>         return -EMSGSIZE;
>>> }
>>>
>>> +static bool rocker_port_dev_check(struct net_device *dev);
>>> +
>>> static netdev_tx_t rocker_port_xmit(struct sk_buff *skb, struct
>>> net_device *dev)
>>> {
>>>         struct rocker_port *rocker_port = netdev_priv(dev);
>>>         struct rocker *rocker = rocker_port->rocker;
>>>         struct rocker_desc_info *desc_info;
>>>         struct rocker_tlv *frags;
>>> +       struct net_device *in_dev;
>>>         int i;
>>>         int err;
>>>
>>> +       if (rocker_port_is_bridged(rocker_port)) {
>>> +               rcu_read_lock();
>>> +               in_dev = dev_get_by_index_rcu(dev_net(dev), skb->skb_iif);
>> Hmm, you iterate over all ports for every xmit call :/
>> Would be nicer if skb_iif would be netdev poiter. Not sure it is doable.
>>
> It may be easier (and faster) to loop through all rocker ports and try to find
> one with the same ifindex. Then the dev_check call would not be necessary.
>
This is still overhead for every packet on the switches we support. The 
number of ports can go close to 128
(40G ports can be broken into 4x10G ports).