iavf: fix VLAN filter lost on add/delete race

[ Upstream commit fc9c69b ]

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: 0c0da0e ("iavf: refactor VLAN filter states")
Signed-off-by: Petr Oros <poros@redhat.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: orosp

drivers/net/ethernet/intel/iavf/iavf_main.c

@@ -757,10 +757,13 @@ 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: