[PATCH net-next v2 1/5] net: stmmac: Fix error handling in VLAN add and delete paths

[Ovidiu Panait]

stmmac_vlan_rx_add_vid() updates active_vlans and the VLAN hash
register before writing the HW filter entry. If the filter write
fails, it leaves a stale VID in active_vlans and the hash register.

stmmac_vlan_rx_kill_vid() has the reverse problem: it clears
active_vlans before removing the HW filter. On failure, the VID is
gone from active_vlans but still present in the HW filter table.

To fix this, reorder the operations to update the hash table first,
then attempt the HW filter operation. If the HW filter fails, roll
back both the active_vlans bitmap and the hash table by calling
stmmac_vlan_update() again.

Fixes: ed64639bc1e0 ("net: stmmac: Add support for VLAN Rx filtering")
Signed-off-by: Ovidiu Panait <ovidiu.panait.rb at renesas.com>
---
v2 changes: none.

 .../net/ethernet/stmicro/stmmac/stmmac_main.c  | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 82375d34ad57..f2f120ddba46 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -6798,9 +6798,13 @@ static int stmmac_vlan_rx_add_vid(struct net_device *ndev, __be16 proto, u16 vid
 
 	if (priv->hw->num_vlan) {
 		ret = stmmac_add_hw_vlan_rx_fltr(priv, ndev, priv->hw, proto, vid);
-		if (ret)
+		if (ret) {
+			clear_bit(vid, priv->active_vlans);
+			stmmac_vlan_update(priv, is_double);
 			goto err_pm_put;
+		}
 	}
+
 err_pm_put:
 	pm_runtime_put(priv->device);
 
@@ -6824,15 +6828,21 @@ static int stmmac_vlan_rx_kill_vid(struct net_device *ndev, __be16 proto, u16 vi
 		is_double = true;
 
 	clear_bit(vid, priv->active_vlans);
+	ret = stmmac_vlan_update(priv, is_double);
+	if (ret) {
+		set_bit(vid, priv->active_vlans);
+		goto del_vlan_error;
+	}
 
 	if (priv->hw->num_vlan) {
 		ret = stmmac_del_hw_vlan_rx_fltr(priv, ndev, priv->hw, proto, vid);
-		if (ret)
+		if (ret) {
+			set_bit(vid, priv->active_vlans);
+			stmmac_vlan_update(priv, is_double);
 			goto del_vlan_error;
+		}
 	}
 
-	ret = stmmac_vlan_update(priv, is_double);
-
 del_vlan_error:
 	pm_runtime_put(priv->device);
 
-- 
2.51.0