Re: [Intel-wired-lan] [PATCH iwl-net] iavf: fix VLAN filter lost on add/delete race

[Petr Oros]

On 2/25/26 12:17, Michal Schmidt wrote:
> On Wed, Feb 25, 2026 at 11:02 AM Petr Oros <poros@xxxxxxxxxx> wrote:
> > When iavf_add_vlan() finds an existing filter in IAVF_VLAN_REMOVE
> > state, it transitions the filter to IAVF_VLAN_ACTIVE assuming the
> > pending delete can simply be cancelled. However, there is no guarantee
> > that iavf_del_vlans() has not already processed the delete AQ request
> > and removed the filter from the PF. In that case the filter remains in
> > the driver's list as IAVF_VLAN_ACTIVE but is no longer programmed on
> > the NIC. Since iavf_add_vlans() only picks up filters in
> > IAVF_VLAN_ADD state, the filter is never re-added, and spoof checking
> > drops all traffic for that VLAN.
> >
> >    CPU0                       CPU1                     Workqueue
> >    ----                       ----                     ---------
> >    iavf_del_vlan(vlan 100)
> >      f->state = REMOVE
> >      schedule AQ_DEL_VLAN
> >                               iavf_add_vlan(vlan 100)
> >                                 f->state = ACTIVE
> >                                                        iavf_del_vlans()
> >                                                          f is ACTIVE, skip
> >                                                        iavf_add_vlans()
> >                                                          f is ACTIVE, skip
> >
> >    Filter is ACTIVE in driver but absent from NIC.
> I don't get it. If, as the diagram shows, iavf_del_vlans() skipped it,
> then how does the filter become absent from NIC?

VLAN teardown            Workqueue           VLAN setup
-------------            ---------           ----------
iavf_del_vlan(100)
  f->state = REMOVE
  schedule AQ_DEL_VLAN
                                             iavf_open()
                                               restore_filters()
                                                 f is REMOVE, skip
                                               iavf_add_vlan(100)
                                                f->state = ACTIVE

                         iavf_del_vlans()
                          f is ACTIVE, skip
                         iavf_add_vlans()
                          f is ACTIVE, skip

Is it clear like this?

> Michal
>
> > Transition to IAVF_VLAN_ADD instead and schedule
> > IAVF_FLAG_AQ_ADD_VLAN_FILTER so iavf_add_vlans() re-programs the
> > filter.  A duplicate add is idempotent on the PF.
> >
> > Fixes: 0c0da0e95105 ("iavf: refactor VLAN filter states")
> >
> > Signed-off-by: Petr Oros <poros@xxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/intel/iavf/iavf_main.c | 9 ++++++---
> >   1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
> > index 4b0fc8f354bc90..6046b93c7f3472 100644
> > --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> > +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> > @@ -782,10 +782,13 @@ iavf_vlan_filter *iavf_add_vlan(struct iavf_adapter *adapter,
> >                  adapter->num_vlan_filters++;
> >                  iavf_schedule_aq_request(adapter, IAVF_FLAG_AQ_ADD_VLAN_FILTER);
> >          } else if (f->state == IAVF_VLAN_REMOVE) {
> > -               /* IAVF_VLAN_REMOVE means that VLAN wasn't yet removed.
> > -                * We can safely only change the state here.
> > +               /* Re-add the filter since we cannot tell whether the
> > +                * pending delete has already been processed by the PF.
> > +                * A duplicate add is harmless.
> >                   */
> > -               f->state = IAVF_VLAN_ACTIVE;
> > +               f->state = IAVF_VLAN_ADD;
> > +               iavf_schedule_aq_request(adapter,
> > +                                        IAVF_FLAG_AQ_ADD_VLAN_FILTER);
> >          }
> >
> >   clearout:
> > --
> > 2.52.0