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.

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 <[email protected]>
---
 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

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