net: bridge: update BROPT_VLAN_ENABLED before notifying switchdev in br_vlan_filter_toggle

SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING is notified by the bridge from
two places:
- nbp_vlan_init(), during bridge port creation
- br_vlan_filter_toggle(), during a netlink/sysfs/ioctl change requested
  by user space

If a switchdev driver uses br_vlan_enabled(br_dev) inside its handler
for the SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING attribute notifier,
different things will be seen depending on whether the bridge calls from
the first path or the second:
- in nbp_vlan_init(), br_vlan_enabled() reflects the current state of
  the bridge
- in br_vlan_filter_toggle(), br_vlan_enabled() reflects the past state
  of the bridge

This can lead in some cases to complications in driver implementation,
which can be avoided if these could reliably use br_vlan_enabled().

Nothing seems to depend on this behavior, and it seems overall more
straightforward for br_vlan_enabled() to return the proper value even
during the SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING notifier, so
temporarily enable the bridge option, then revert it if the switchdev
notifier failed.

Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: Nikolay Aleksandrov <nikolay@nvidia.com>
Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_vlan.c

@@ -840,11 +840,14 @@ int br_vlan_filter_toggle(struct net_bridge *br, unsigned long val,
 	if (br_opt_get(br, BROPT_VLAN_ENABLED) == !!val)
 		return 0;
 
+	br_opt_toggle(br, BROPT_VLAN_ENABLED, !!val);
+
 	err = switchdev_port_attr_set(br->dev, &attr, extack);
-	if (err && err != -EOPNOTSUPP)
+	if (err && err != -EOPNOTSUPP) {
+		br_opt_toggle(br, BROPT_VLAN_ENABLED, !val);
 		return err;
+	}
 
-	br_opt_toggle(br, BROPT_VLAN_ENABLED, !!val);
 	br_manage_promisc(br);
 	recalculate_group_addr(br);
 	br_recalculate_fwd_mask(br);