RE: [RFC PATCH net-next 1/1] net: Support for switch port configuration

[Varlese, Marco]

> -----Original Message-----
> From: Roopa Prabhu [mailto:roopa@xxxxxxxxxxxxxxxxxxx]
> Sent: Saturday, December 13, 2014 7:06 AM
> To: Varlese, Marco
> Cc: Jiri Pirko; John Fastabend; netdev@xxxxxxxxxxxxxxx;
> stephen@xxxxxxxxxxxxxxxxxx; Fastabend, John R; sfeldma@xxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [RFC PATCH net-next 1/1] net: Support for switch port
> configuration
> 
> On 12/12/14, 1:19 AM, Varlese, Marco wrote:
> >> -----Original Message-----
> >> From: Roopa Prabhu [mailto:roopa@xxxxxxxxxxxxxxxxxxx]
> >> Sent: Thursday, December 11, 2014 5:41 PM
> >> To: Jiri Pirko
> >> Cc: Varlese, Marco; John Fastabend; netdev@xxxxxxxxxxxxxxx;
> >> stephen@xxxxxxxxxxxxxxxxxx; Fastabend, John R; sfeldma@xxxxxxxxx;
> >> linux-kernel@xxxxxxxxxxxxxxx
> >> Subject: Re: [RFC PATCH net-next 1/1] net: Support for switch port
> >> configuration
> >>
> >> On 12/11/14, 8:56 AM, Jiri Pirko wrote:
> >>> Thu, Dec 11, 2014 at 05:37:46PM CET, roopa@xxxxxxxxxxxxxxxxxxx
> wrote:
> >>>> On 12/11/14, 3:01 AM, Jiri Pirko wrote:
> >>>>> Thu, Dec 11, 2014 at 10:59:42AM CET, marco.varlese@xxxxxxxxx wrote:
> >>>>>>> -----Original Message-----
> >>>>>>> From: John Fastabend [mailto:john.fastabend@xxxxxxxxx]
> >>>>>>> Sent: Wednesday, December 10, 2014 5:04 PM
> >>>>>>> To: Jiri Pirko
> >>>>>>> Cc: Varlese, Marco; netdev@xxxxxxxxxxxxxxx;
> >>>>>>> stephen@xxxxxxxxxxxxxxxxxx; Fastabend, John R;
> >>>>>>> roopa@xxxxxxxxxxxxxxxxxxx; sfeldma@xxxxxxxxx; linux-
> >>>>>>> kernel@xxxxxxxxxxxxxxx
> >>>>>>> Subject: Re: [RFC PATCH net-next 1/1] net: Support for switch
> >>>>>>> port configuration
> >>>>>>>
> >>>>>>> On 12/10/2014 08:50 AM, Jiri Pirko wrote:
> >>>>>>>> Wed, Dec 10, 2014 at 05:23:40PM CET, marco.varlese@xxxxxxxxx
> >> wrote:
> >>>>>>>>> From: Marco Varlese <marco.varlese@xxxxxxxxx>
> >>>>>>>>>
> >>>>>>>>> Switch hardware offers a list of attributes that are
> >>>>>>>>> configurable on a per port basis.
> >>>>>>>>> This patch provides a mechanism to configure switch ports by
> >>>>>>>>> adding an NDO for setting specific values to specific attributes.
> >>>>>>>>> There will be a separate patch that extends iproute2 to call
> >>>>>>>>> the new NDO.
> >>>>>>>> What are these attributes? Can you give some examples. I'm
> >>>>>>>> asking because there is a plan to pass generic attributes to
> >>>>>>>> switch ports replacing current specific
> >>>>>>>> ndo_switch_port_stp_update. In this case, bridge is setting that
> attribute.
> >>>>>>>>
> >>>>>>>> Is there need to set something directly from userspace or does
> >>>>>>>> it make rather sense to use involved bridge/ovs/bond ? I think
> >>>>>>>> that both will be needed.
> >>>>>>> +1
> >>>>>>>
> >>>>>>> I think for many attributes it would be best to have both. The
> >>>>>>> in kernel callers and netlink userspace can use the same driver
> ndo_ops.
> >>>>>>>
> >>>>>>> But then we don't _require_ any specific bridge/ovs/etc module.
> >>>>>>> And we may have some attributes that are not specific to any
> >>>>>>> existing software module. I'm guessing Marco has some examples
> >>>>>>> of
> >> these.
> >>>>>>> [...]
> >>>>>>>
> >>>>>>>
> >>>>>>> --
> >>>>>>> John Fastabend         Intel Corporation
> >>>>>> We do have a need to configure the attributes directly from
> >>>>>> user-space
> >> and I have identified the tool to do that in iproute2.
> >>>>>> An example of attributes are:
> >>>>>> * enabling/disabling of learning of source addresses on a given
> >>>>>> port (you can imagine the attribute called LEARNING for example);
> >>>>>> * internal loopback control (i.e. LOOPBACK) which will control
> >>>>>> how the flow of traffic behaves from the switch fabric towards an
> >>>>>> egress port;
> >>>>>> * flooding for broadcast/multicast/unicast type of packets (i.e.
> >>>>>> BFLOODING, MFLOODING, UFLOODING);
> >>>>>>
> >>>>>> Some attributes would be of the type enabled/disabled while other
> >>>>>> will
> >> allow specific values to allow the user to configure different
> >> behaviours of that feature on that particular port on that platform.
> >>>>>> One thing to mention - as John stated as well - there might be
> >>>>>> some
> >> attributes that are not specific to any software module but rather
> >> have to do with the actual hardware/platform to configure.
> >>>>>> I hope this clarifies some points.
> >>>>> It does. Makes sense. We need to expose this attr set/get for both
> >>>>> in-kernel and userspace use cases.
> >>>>>
> >>>>> Please adjust you patch for this. Also, as a second patch, it
> >>>>> would be great if you can convert ndo_switch_port_stp_update to
> >>>>> this new
> >> ndo.
> >>>> Why are we exposing generic switch attribute get/set from userspace
> >>>> ?. We already have specific attributes for learning/flooding which
> >>>> can be extended further.
> >>> Yes, but that is for PF_BRIDGE and bridge specific attributes. There
> >>> might be another generic attrs, no?
> >> I cant think of any. And plus, the whole point of switchdev l2
> >> offloads was to map these to existing bridge attributes. And we
> >> already have a match for some of the attributes that marco wants.
> >>
> >> If there is a need for such attributes, i don't see why it is needed
> >> for switch devices only.
> >> It is needed for any hw (nics etc). And, a precedence to this is to
> >> do it via ethtool.
> >>
> >> Having said that, am sure we will find a need for this in the future.
> >> And having a netlink attribute always helps.
> >>
> >> Today, it seems like these can be mapped to existing attributes that
> >> are settable via ndo_bridge_setlink/getlink.
> >>
> >>>> And for in kernel api....i had a sample patch in my RFC series
> >>>> (Which i was going to resubmit, until it was decided that we will
> >>>> use existing api around
> >>>> ndo_bridge_setlink/ndo_bridge_getlink):
> >>>> http://www.spinics.net/lists/netdev/msg305473.html
> >>> Yes, this might become handy for other generic non-bridge attrs.
> >>>
> >>>> Thanks,
> >>>> Roopa
> >>>>
> >>>>
> >>>>
> > The list I provided is only a subset of the attributes we will need to be
> exposed. I do have more and I'm sure that more will come in the future. As I
> mentioned in few posts earlier, some attributes are generic and some are
> not.
> >
> > I did not consider ethtool for few reasons but the main one is that I was
> under the impression that netlink was preferred in many circumstances over
> the ethotool_ops.
> That is correct. I don't think anybody hinted that you should extend ethtool.
> >   Plus, all the cases I have identified so far are going to nicely fit into the
> setlink set of operations.
> >
> 
> Would be better if you submitted your iproute2 patch with this patch.
> 
> I do plan to resubmit my generic ndo patch soon.
> 
> Thanks,
> Roopa

I honestly do not understand what extra "help" the iproute2 would have brought to this RFC: that patch simply adds a new section for the iproute2 help and a new args parser for the input. From an infrastructure perspective is leveraging what netlink messages are using RTM_SETLINK hence hooking up eventually in the do_setlink(). Sure, obviously contains all the attributes I have in mind but from an infrastructure patch perspective I don't think that you would have gained much in seeing it.

Anyway, good to know you're reworking you generic patch. I'll keep an eye out for your new NDO.


Thanks,
Marco

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