netdev - [RFC PATCH net-next 2/5] net: bridge: vlan: nbp_vlan

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Date:   Wed,  9 Feb 2022 23:30:40 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        Rafael Richter <rafael.richter@....de>,
        Daniel Klauer <daniel.klauer@....de>,
        Tobias Waldekranz <tobias@...dekranz.com>
Subject: [RFC PATCH net-next 2/5] net: bridge: vlan: nbp_vlan_add: notify switchdev only when changed

When a VLAN entry is added multiple times in a row to a bridge port:

bridge vlan add dev lan12 vid 100 master static

the bridge notifies switchdev each time, even if nothing changed, which
makes driver-level accounting impossible.

Since nbp_vlan_add() changes only the flags of the existing port VLAN,
record the old flags, and restore them on the error path of
br_switchdev_port_vlan_add().

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/bridge/br_vlan.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index c7cadc1b4f71..3c149b54124e 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -1279,11 +1279,18 @@ int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags,
 	*changed = false;
 	vlan = br_vlan_find(nbp_vlan_group(port), vid);
 	if (vlan) {
-		/* Pass the flags to the hardware bridge */
-		ret = br_switchdev_port_vlan_add(port->dev, vid, flags, extack);
-		if (ret && ret != -EOPNOTSUPP)
-			return ret;
+		u16 old_flags = vlan->flags;
+
 		*changed = __vlan_add_flags(vlan, flags);
+		if (*changed) {
+			/* Pass the flags to the hardware bridge */
+			ret = br_switchdev_port_vlan_add(port->dev, vid, flags,
+							 extack);
+			if (ret && ret != -EOPNOTSUPP) {
+				__vlan_add_flags(vlan, old_flags);
+				return ret;
+			}
+		}
 
 		return 0;
 	}
-- 
2.25.1