Re: [dpdk-dev] [PATCH v3 1/3] net/mlx5: use Netlink to add/remove MAC addresses

[Shahaf Shuler <shahafs@mellanox.com>]

Thursday, March 22, 2018 12:29 PM, Nélio Laranjeiro:
> On Thu, Mar 22, 2018 at 09:45:16AM +0000, Shahaf Shuler wrote:
> > Thursday, March 22, 2018 11:05 AM, Nélio Laranjeiro:
> > > > What if the DPDK process is terminated ungracefully? I think the
> > > > MAC table will remain with all the MACs which were added.
> > > > The next run of the process may have un-expected results.
> > > >
> > > > Should we flush the neighbor mac table also on probe to make sure
> > > > only the VF mac exists?
> > >
> > > In such situation the sysadmin should make the clean up, the DPDK
> > > application cannot consider it is the only one using the device as
> > > it is not the case, Linux still owns the device.
> > > We have no guarantee the admin did not use another MAC address for a
> > > service outside of the DPDK application (even if in such case he
> > > should disable this feature to fully control what happens on the neighbor
> mac table).
> >
> > There should be only one owner for the VF mac tables - either the DPDK or
> the Linux.
> >
> > If the DPDK is the owner, it should do the cleanup. If the sysadmin
> > wants to be the owner then it should set the proper flag when running
> > dpdk or alternatively not set the VF in trusted mode.
> 
> It is a little more complex than what you think, according to the Linux
> configuration the tables will have entries already present or not e.g.
> broadcast v6 is present only if the Linux supports the v6 (by compilation or
> configuration).
> 
> For such reason the PMD cannot consider it owns the bridge tables when
> acting as a VF, otherwise it needs to trigger any Linux configuration
> modification and enable the according functionalities.

OK. 

Then I think a proper documentation is needed as part of this patch in mlx guide.
To explain the application that a cleanup of the neighbor table is needed in case the PMD is terminated ungracefully. 

> 
> To answer this:
> > There should be only one owner for the VF mac tables - either the DPDK or
> the Linux.
> 
> That's right, DPDK application or Linux should own the device, the PMD is
> none of the two.  It is just a driver.
> 
> Thanks,
> 
> --
> Nélio Laranjeiro
> 6WIND