On 2/9/12 9:36 AM, "John Fastabend" <john.r.fastabend@xxxxxxxxx> wrote:
> On 2/8/2012 8:36 PM, Stephen Hemminger wrote:
>> On Wed, 08 Feb 2012 19:22:06 -0800
>> John Fastabend <john.r.fastabend@xxxxxxxxx> wrote:
>>
>>> Propagate software FDB table into hardware uc, mc lists when
>>> the NETIF_F_HW_FDB is set.
>>>
>>> This resolves the case below where an embedded switch is used
>>> in hardware to do inter-VF or VF-PF switching. This patch
>>> pushes the FDB entry (specifically the MAC address) into the
>>> embedded switch with dev_add_uc and dev_add_mc so the switch
>>> "learns" about the software bridge.
>>>
>>>
>>> veth0 veth2
>>> | |
>>> ------------
>>> | bridge0 | <---- software bridging
>>> ------------
>>> /
>>> /
>>> ethx.y ethx
>>> VF PF
>>> \ \ <---- propagate FDB entries to HW
>>> \ \
>>> --------------------
>>> | Embedded Bridge | <---- hardware offloaded switching
>>> --------------------
>>>
>>> This is only an RFC couple more changes are needed.
>>>
>>> (1) Optimize HW FDB set/del to only walk list if an FDB offloaded
>>> device is attached. Or decide it doesn't matter from unlikely()
>>> path.
>>>
>>> (2) Is it good enough to just call dev_uc_{add|del} or
>>> dev_mc_{add|del}? Or do some devices really need a new netdev
>>> callback to do this operation correctly. I think it should be
>>> good enough as is.
>>>
>>> (3) wrapped list walk in rcu_read_lock() just in case maybe every
>>> case is already inside rcu_read_lock()/unlock().
>>>
>>> Also this is in response to this thread regarding the macvlan and
>>> exposing rx filters posting now to see if folks think this is the
>>> right idea and if it will resolve at least the bridge case.
>>>
>>> http://lists.openwall.net/netdev/2011/11/08/135
>>>
>>> Signed-off-by: John Fastabend <john.r.fastabend@xxxxxxxxx>
>>> ---
>>>
>>> include/linux/netdev_features.h | 2 ++
>>> net/bridge/br_fdb.c | 34 ++++++++++++++++++++++++++++++++++
>>> 2 files changed, 36 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/include/linux/netdev_features.h
>>> b/include/linux/netdev_features.h
>>> index 77f5202..5936fae 100644
>>
>> Rather than yet another device feature, I would rather use netlink_notifier
>> callback. The notifier is more general and generic without messing with
>> internals
>> of bridge.
>>
>
> But the device features makes it easy for user space to learn that the device
> supports this sort of offload. Now if all SR-IOV devices support this then it
> doesn't matter but I thought there were SR-IOV devices that didn't do any
> switching? I'll dig through the SR-IOV drivers to check there are not too
> many of them.
Correct. Our 802.1Qbh sriov device (enic) does not do local switching.
>
> By netlink_notifier do you mean adding a notifier_block and using
> atomic_notifier_call_chain()
> probably in rtnl_notify()? Then drivers could register with the notifier chain
> with
> atomic_notifier_chain_register() and receive the events correctly. Or did I
> miss
> some notifier chain that already exists?
>
> Thanks,
> John
>
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