Re: [dpdk-dev] [PATCH] app/testpmd: fix flow rules list after port stop

[Ori Kam <orika@nvidia.com>]

Hi Ferruh,
Can we proceed with this patch?

Thanks,
Ori
> -----Original Message-----
> From: Ori Kam
> 
> Hi Ferruh,
> 
> > -----Original Message-----
> > From: Ferruh Yigit <ferruh.yigit@intel.com>
> >
> > On 8/20/2020 9:40 AM, Gregory Etelson wrote:
> > > Hello,
> > >
> > > Is this patch scheduled for merge with dpdk.org ?
> > > Please update me.
> > >
> > > Regards,
> > > Gregory
> > >
> > >> -----Original Message-----
> > >> From: Gregory Etelson <getelson@mellanox.com>
> > >>
> > >> According to current RTE API, port flow rules must not be kept after port
> > >> stop.
> >
> > Hi Gregory, Ori,
> >
> > Can you please point where this is documented?
> >
> From: rte_ethdev.h
> "Please note that some configuration is not stored between calls to
>  rte_eth_dev_stop()/rte_eth_dev_start(). The following configuration will
>  be retained:
> 
>      - MTU
>      - flow control settings
>      - receive mode configuration (promiscuous mode, all-multicast mode,
>        hardware checksum mode, RSS/VMDQ settings etc.)
>      - VLAN filtering configuration
>      - default MAC address
>      - MAC addresses supplied to MAC address array
>      - flow director filtering mode (but not filtering rules)
>      - NIC queue statistics mappings"
> 
> From my understanding this means that flows should not be stored on device
> stop.
> 
> 
> > >>
> > >> Testpmd did not flush port flow rules after `port stop' command was
> called.
> > >> As the result, after the port was restarted, it showed bogus flow rules.
> >
> > There are two issues,
> >
> > 1) According what I see in the rte_flow documentation, not sure if the "port
> > stop" should clear the rules:
> > "
> > PMDs, not applications, are responsible for maintaining flow rules
> > configuration
> > when stopping and restarting a port or performing other actions which may
> > affect
> > them. They can only be destroyed explicitly by applications.
> > "
> >
> Good catch I think this part should be removed, since it has many issues. The
> application is the only
> one that can be responsible for the rules.
> 
> Thinks about the following scenario: application configures 2 queues 0 and 1.
> It insert flow with queue action 1.
> It stops the port and remove queue 1. What should the PMD do?
> What happens if he changed some thing else in configuration that make
> the actions invalid?
> 
> For those reason (the description in rte_ethdev.h and the above issues with
> keeping the rules)
> we (Mellanox) modified our code to remove the flows in stop function from the
> device.
> This code was inserted to DPDK in 20.05 release.
> One more reason is that saving the flows also waste a lot of memory
> which is very costly to many applications.
> 
> 
> > As I tested with i40e, it keeps the rules after stop/start, cc'ing @Jeff,
> > @Beilei & @Qi if this is done intentionally.
> >
> >
> > 2) From the perspective of the testers, users of the testpmd. If they are
> > testing a complex set of filter rules, stopping and starting the port flushing
> > all rules may be troublesome.
> > Since there is explicit command to remove a rte_flow rule or to remove them
> > all,
> > user may prefer to call it when required to delete the rules, instead of this is
> > done implicitly in port stop.
> >
> > Btw, this is based on PMD should handle the rules on stop/start, we need to
> > agree on it first, but even that is not the case, we are in the application
> > domain now and we can apply the rules back again in the 'start' if it serves
> > better to the user.
> >
> First like I said above I think we should agree that it is the application
> responsibility to manage the rules and not the PMD, and first thing to do it
> update the rte_flow doc.
> 
> Second I agree that we should discuss if test-pmd should keep the rules and
> reapply them,
> but just like for the PMD the user may create invalid configuration, so re-
> applying the rules
> maybe incorrect.
> Currently test-pmd is not build to support large number of rules, unless using a
> script, and if the user uses a script
> he can reuse this script.
> 
> 
> 
> Best,
> Ori