[PATCH RFC iwl-next 3/4] iavf: wait for PF confirmation before removing VLAN filters

[Petr Oros <poros@redhat.com>]

The VLAN filter DELETE path was asymmetric with the ADD path: ADD
waits for PF confirmation (ADD -> ADDING -> ACTIVE), but DELETE
immediately frees the filter struct after sending the DEL message
without waiting for the PF response.

This is problematic because:
 - If the PF rejects the DEL, the filter remains in HW but the driver
   has already freed the tracking structure, losing sync.
 - Race conditions between DEL pending and other operations
   (add, reset) cannot be properly resolved if the filter struct
   is already gone.

Add IAVF_VLAN_REMOVING state to make the DELETE path symmetric:

  REMOVE -> REMOVING (send DEL) -> PF confirms -> kfree
                                -> PF rejects  -> ACTIVE

In iavf_del_vlans(), transition filters from REMOVE to REMOVING
instead of immediately freeing them. The new DEL completion handler
in iavf_virtchnl_completion() frees filters on success or reverts
them to ACTIVE on error.

Update iavf_add_vlan() to handle the REMOVING state: if a DEL is
pending and the user re-adds the same VLAN, queue it for ADD so
it gets re-programmed after the PF processes the DEL.

The !VLAN_FILTERING_ALLOWED early-exit path still frees filters
directly since no PF message is sent in that case.

Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/iavf/iavf.h        |  1 +
 drivers/net/ethernet/intel/iavf/iavf_main.c   |  9 +++--
 .../net/ethernet/intel/iavf/iavf_virtchnl.c   | 37 +++++++++++++------
 3 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h
index 1ad00690622c8e..f9ad814d18b1da 100644
--- a/drivers/net/ethernet/intel/iavf/iavf.h
+++ b/drivers/net/ethernet/intel/iavf/iavf.h
@@ -161,6 +161,7 @@ enum iavf_vlan_state_t {
 	IAVF_VLAN_ADDING,	/* ADD sent to PF, waiting for response */
 	IAVF_VLAN_ACTIVE,	/* PF confirmed, filter is in HW */
 	IAVF_VLAN_REMOVE,	/* filter queued for DEL from PF */
+	IAVF_VLAN_REMOVING,	/* DEL sent to PF, waiting for response */
 };
 
 struct iavf_vlan_filter {
diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index f1ab68f5f4050b..212a23ead20c57 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.
-		 */
+		/* DEL not yet sent to PF, cancel it */
 		f->state = IAVF_VLAN_ACTIVE;
+	} else if (f->state == IAVF_VLAN_REMOVING) {
+		/* DEL already sent to PF, re-add after completion */
+		f->state = IAVF_VLAN_ADD;
+		iavf_schedule_aq_request(adapter,
+					 IAVF_FLAG_AQ_ADD_VLAN_FILTER);
 	}
 
 clearout:
diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
index d62c0d6394149e..9f2b64bb4ed9e7 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
@@ -948,12 +948,10 @@ void iavf_del_vlans(struct iavf_adapter *adapter)
 
 		vvfl->vsi_id = adapter->vsi_res->vsi_id;
 		vvfl->num_elements = count;
-		list_for_each_entry_safe(f, ftmp, &adapter->vlan_filter_list, list) {
+		list_for_each_entry(f, &adapter->vlan_filter_list, list) {
 			if (f->state == IAVF_VLAN_REMOVE) {
 				vvfl->vlan_id[i] = f->vlan.vid;
-				list_del(&f->list);
-				kfree(f);
-				adapter->num_vlan_filters--;
+				f->state = IAVF_VLAN_REMOVING;
 				i++;
 				if (i == count)
 					break;
@@ -990,7 +988,7 @@ void iavf_del_vlans(struct iavf_adapter *adapter)
 
 		vvfl_v2->vport_id = adapter->vsi_res->vsi_id;
 		vvfl_v2->num_elements = count;
-		list_for_each_entry_safe(f, ftmp, &adapter->vlan_filter_list, list) {
+		list_for_each_entry(f, &adapter->vlan_filter_list, list) {
 			if (f->state == IAVF_VLAN_REMOVE) {
 				struct virtchnl_vlan_supported_caps *filtering_support =
 					&adapter->vlan_v2_caps.filtering.filtering_support;
@@ -1005,9 +1003,7 @@ void iavf_del_vlans(struct iavf_adapter *adapter)
 				vlan->tci = f->vlan.vid;
 				vlan->tpid = f->vlan.tpid;
 
-				list_del(&f->list);
-				kfree(f);
-				adapter->num_vlan_filters--;
+				f->state = IAVF_VLAN_REMOVING;
 				i++;
 				if (i == count)
 					break;
@@ -2370,10 +2366,6 @@ void iavf_virtchnl_completion(struct iavf_adapter *adapter,
 			ether_addr_copy(adapter->hw.mac.addr, netdev->dev_addr);
 			wake_up(&adapter->vc_waitqueue);
 			break;
-		case VIRTCHNL_OP_DEL_VLAN:
-			dev_err(&adapter->pdev->dev, "Failed to delete VLAN filter, error %s\n",
-				iavf_stat_str(&adapter->hw, v_retval));
-			break;
 		case VIRTCHNL_OP_DEL_ETH_ADDR:
 			dev_err(&adapter->pdev->dev, "Failed to delete MAC filter, error %s\n",
 				iavf_stat_str(&adapter->hw, v_retval));
@@ -2896,6 +2888,27 @@ void iavf_virtchnl_completion(struct iavf_adapter *adapter,
 		spin_unlock_bh(&adapter->mac_vlan_list_lock);
 		}
 		break;
+	case VIRTCHNL_OP_DEL_VLAN:
+	case VIRTCHNL_OP_DEL_VLAN_V2: {
+		struct iavf_vlan_filter *f, *ftmp;
+
+		spin_lock_bh(&adapter->mac_vlan_list_lock);
+		list_for_each_entry_safe(f, ftmp, &adapter->vlan_filter_list,
+					 list) {
+			if (f->state == IAVF_VLAN_REMOVING) {
+				if (v_retval) {
+					/* PF rejected DEL, filter is still in HW */
+					f->state = IAVF_VLAN_ACTIVE;
+				} else {
+					list_del(&f->list);
+					kfree(f);
+					adapter->num_vlan_filters--;
+				}
+			}
+		}
+		spin_unlock_bh(&adapter->mac_vlan_list_lock);
+		}
+		break;
 	case VIRTCHNL_OP_ENABLE_VLAN_STRIPPING:
 		/* PF enabled vlan strip on this VF.
 		 * Update netdev->features if needed to be in sync with ethtool.
-- 
2.52.0