net: bridge: add helper to set topology change

Add a __br_set_topology_change helper to set the topology change value.

This can be later extended to add actions when the topology change flag
is set or cleared.

Signed-off-by: Vivien Didelot <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/br_private_stp.h

···
 void br_transmit_config(struct net_bridge_port *p);
 void br_transmit_tcn(struct net_bridge *br);
 void br_topology_change_detection(struct net_bridge *br);
+void __br_set_topology_change(struct net_bridge *br, unsigned char val);
 
 /* br_stp_bpdu.c */
 void br_send_config_bpdu(struct net_bridge_port *, struct br_config_bpdu *);

net/bridge/br_stp.c

···
 	br->max_age = bpdu->max_age;
 	br->hello_time = bpdu->hello_time;
 	br->forward_delay = bpdu->forward_delay;
-	br->topology_change = bpdu->topology_change;
+	__br_set_topology_change(br, bpdu->topology_change);
 }
 
 /* called under bridge lock */
···
 		isroot ? "propagating" : "sending tcn bpdu");
 
 	if (isroot) {
-		br->topology_change = 1;
+		__br_set_topology_change(br, 1);
 		mod_timer(&br->topology_change_timer, jiffies
 			  + br->bridge_forward_delay + br->bridge_max_age);
 	} else if (!br->topology_change_detected) {
···
 	mod_timer(&br->gc_timer, jiffies);
 
 	return 0;
+}
+
+/* called under bridge lock */
+void __br_set_topology_change(struct net_bridge *br, unsigned char val)
+{
+	br->topology_change = val;
 }
 
 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)

net/bridge/br_stp_if.c

···
 
 	}
 
-	br->topology_change = 0;
+	__br_set_topology_change(br, 0);
 	br->topology_change_detected = 0;
 	spin_unlock_bh(&br->lock);
 

net/bridge/br_stp_timer.c

···
 	br_debug(br, "topo change timer expired\n");
 	spin_lock(&br->lock);
 	br->topology_change_detected = 0;
-	br->topology_change = 0;
+	__br_set_topology_change(br, 0);
 	spin_unlock(&br->lock);
 }