[BRIDGE]: handle speed detection after carrier changes

Speed of a interface may not be available until carrier
is detected in the case of autonegotiation. To get the correct value
we need to recheck speed after carrier event.  But the check needs to
be done in a context that is similar to normal ethtool interface (can sleep).

Also, delay check for 1ms to try avoid any carrier bounce transitions.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_private.h

@@ -27,6 +27,8 @@
 #define BR_PORT_BITS	10
 #define BR_MAX_PORTS	(1<<BR_PORT_BITS)
 
+#define BR_PORT_DEBOUNCE (HZ/10)
+
 typedef struct bridge_id bridge_id;
 typedef struct mac_addr mac_addr;
 typedef __u16 port_id;
@@ -78,6 +80,7 @@ struct net_bridge_port
 	struct timer_list		hold_timer;
 	struct timer_list		message_age_timer;
 	struct kobject			kobj;
+	struct work_struct		carrier_check;
 	struct rcu_head			rcu;
 };