netdev - Re: [patch net-next v3 02/17] net: make vid as a parameter for ndo_fdb_add/ndo_fdb

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Date:	Fri, 28 Nov 2014 02:14:53 -0800
From:	Roopa Prabhu <roopa@...ulusnetworks.com>
To:	Scott Feldman <sfeldma@...il.com>
CC:	Jamal Hadi Salim <jhs@...atatu.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Jiri Pirko <jiri@...nulli.us>, Netdev <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	"nhorman@...driver.com" <nhorman@...driver.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	Thomas Graf <tgraf@...g.ch>,
	"dborkman@...hat.com" <dborkman@...hat.com>,
	"ogerlitz@...lanox.com" <ogerlitz@...lanox.com>,
	"jesse@...ira.com" <jesse@...ira.com>,
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	"ben@...adent.org.uk" <ben@...adent.org.uk>,
	"stephen@...workplumber.org" <stephen@...workplumber.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"vyasevic@...hat.com" <vyasevic@...hat.com>,
	Cong Wang <xiyou.wangcong@...il.com>,
	Eric Dumazet <edumazet@...gle.com>,
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	John Linville <linville@...driver.com>,
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	Shrijeet Mukherjee <shrijeet@...il.com>,
	Andy Gospodarek <gospo@...ulusnetworks.com>,
	Benjamin LaHaise <bcrl@...ck.org>
Subject: Re: [patch net-next v3 02/17] net: make vid as a parameter for ndo_fdb_add/ndo_fdb_del

On 11/25/14, 6:36 PM, Scott Feldman wrote:
> On Tue, Nov 25, 2014 at 6:50 AM, Jamal Hadi Salim <jhs@...atatu.com> wrote:
>> On 11/25/14 11:30, John Fastabend wrote:
>>> On 11/25/2014 08:18 AM, Jamal Hadi Salim wrote:
>>>> On 11/25/14 11:01, John Fastabend wrote:
>>>>> On 11/25/2014 07:38 AM, Jamal Hadi Salim wrote:
>>>>>> On 11/25/14 05:28, Jiri Pirko wrote:
>>>>>>> Do the work of parsing NDA_VLAN directly in rtnetlink code, pass
>>>>>>> simple
>>>>>>> u16 vid to drivers from there.
>>>>>>>
>>
>>> Actually (after having some coffee) this becomes much more useful
>>> if you return which items failed. Then you can slam the hardware
>>> with your 100 entries, probably a lot more then that, and come back
>>> later and clean it up.
>>>
>> Yes, that is the general use case.
>> Unfortunately at the moment we only return codes on a netlink set
>> direction - but would be a beauty if we could return what succeeded
>> and didnt in some form of vector.
>> Note: all is not lost because you can always do a get afterwards and
>> find what is missing if you got a return code of "partial success".
>> Just a little less efficient..
>>
>>
>>> We return a bitmask of which operations were successful. So if SW fails
>>> we have both bits cleared and we abort. When SW is successful we set the
>>> SW bit and try to program the HW. If its sucessful we set the HW bit if
>>> its not we abort with an err. Converting this to (1) is not much work
>>> just skip the abort.
>>>
>> Ok, guess i am gonna have to go stare at the code some more.
>> I thought we returned one of the error codes?
>> A bitmask would work for a single entry - because you have two
>> options add to h/ware and/or s/ware. So response is easy to encode.
>> But if i have 1000 and they are sparsely populated (think an indexed
>> table and i have indices 1, 23, 45, etc), then a bitmask would be
>> hard to use.
> I'm confused by this discussion.  Do I have this right: You want to
> send 1000 RTM_NEWNEIGHs to PF_BRIDGE with both NTF_MASTER and NTF_SELF
> set such that 1000 new FBD entries are installed in both (SW) the
> bridge's FDB and (HW) the port driver's FDB.  My first confusion is
> why do you want these FBD entries in bridge's FDB?  We're offloading
> the switching to HW so HW should be handling fwd plane.  If ctrl pkt
> make it to SW, it can learn those FDB entries; no need for manual
> install of FDB entry in SW.  It seems to me you only want to use
> NTF_SELF to install the FDB entry in HW using the port driver.  And an
> error code is returned for that install.  Since there is only one
> target (NTF_SELF) there is no need for bitmask return.
>
scott, we do have such usecase today. ie , a fdb entry with both 
NTF_MASTER and NTF_SELF set.
And these fdb entries can come from an external controller. The path to 
get them to the hw is via the kernel.
The controller can use `bridge fdb add` to add the fdb entries to the 
kernel (with NTF_MASTER) and also indicate in the same message to add 
the fdb entry to hw (with NTF_SELF). And in this model it is assumed 
that the kernel fdb and hw fdb are in sync.
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