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

[Michal Schmidt]

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?

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
>