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:	Tue, 25 Nov 2014 17:59:19 -1000
From:	Scott Feldman <sfeldma@...il.com>
To:	Jamal Hadi Salim <jhs@...atatu.com>
Cc:	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>,
	"pshelar@...ira.com" <pshelar@...ira.com>,
	"azhou@...ira.com" <azhou@...ira.com>,
	"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>,
	Florian Fainelli <f.fainelli@...il.com>,
	Roopa Prabhu <roopa@...ulusnetworks.com>,
	John Linville <linville@...driver.com>,
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	Aviad Raveh <aviadr@...lanox.com>,
	"nbd@...nwrt.org" <nbd@...nwrt.org>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Neil Jerram <Neil.Jerram@...aswitch.com>,
	"ronye@...lanox.com" <ronye@...lanox.com>,
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	"alexander.h.duyck@...hat.com" <alexander.h.duyck@...hat.com>,
	"Ronciak, John" <john.ronciak@...el.com>,
	"mleitner@...hat.com" <mleitner@...hat.com>,
	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 Tue, Nov 25, 2014 at 5:19 PM, Jamal Hadi Salim <jhs@...atatu.com> wrote:
> On 11/25/14 21:36, 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:
>
>
>>> 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.
>
>
> This is about the policy which states "install as many as you can, dont
> worry about failures". In such a case, how do you tell user space back
> "oh, btw you know your request #1, #23, and 45 went ok, but nothing else
> worked". A simple return code wont work. You could return a code to
> say "some worked". At which case user space could dump and find out only
> #1, #23 and #45 worked.

You request for what?  That's my confusion.  Are you trying to install
FDB entry into both SW and HW at same time?  And then do a bunch in a
batch?  I'm saying use MASTER for SW and SELF for HW in two steps, if
you want FDB entry installed in both Sw and HW.  Check your return
code each step.  Batch all to HW first, then batch all that PASSED to
SW.  I don't even know really why you're trying to install to both HW
and SW.  Install it to HW and be done. fdb_dump will set HW entries
via SELF.

> Your question below is a different context; Some people may want
> the policy where whats in hardware
> a) gets to be seen in software and b) allow for destination lookup
> failures in hardware to show up in the kernel, refresh the fdb in the
> kernel via learning
> and c) whats in s.ware gets synced to hardware just because there's
> space in the hardware
> I dont want any of the above;-> Which would work if we had policy knobs.
> Learning, flooding, sync from hardware. Speaking of the last one:
> Where is my cookie Scott? I want my cookie.

Ah, Jamal, look again at patches 13-17/17 in last v3 set.  That was a
big steaming snickerdoodle just for you!  Now you can push policy
knobs down to port driver and or bridge to fine tune what ever you
want.  You'll find knobs for learning, flooding, learning sync to hw,
etc.  I thought you even ACKed some of these.  a) above knob is 14/17
patch, b) above is using existing learning knob on bridge, c) above I
don't get...no point in syncing that direction.

> cheers,
> jamal
>
>
>
>> 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.
>
>
>
>
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