net: count hw_addr syncs so that unsync works properly.

[ Upstream commit 4543fbef ]

A few drivers use dev_uc_sync/unsync to synchronize the
address lists from master down to slave/lower devices.  In
some cases (bond/team) a single address list is synched down
to multiple devices.  At the time of unsync, we have a leak
in these lower devices, because "synced" is treated as a
boolean and the address will not be unsynced for anything after
the first device/call.

Treat "synced" as a count (same as refcount) and allow all
unsync calls to work.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

include/linux/netdevice.h

@@ -225,9 +225,9 @@ struct netdev_hw_addr {
 #define NETDEV_HW_ADDR_T_SLAVE		3
 #define NETDEV_HW_ADDR_T_UNICAST	4
 #define NETDEV_HW_ADDR_T_MULTICAST	5
-	bool			synced;
 	bool			global_use;
 	int			refcount;
+	int			synced;
 	struct rcu_head		rcu_head;
 };
 

net/core/dev_addr_lists.c

@@ -57,7 +57,7 @@ static int __hw_addr_add_ex(struct netdev_hw_addr_list *list,
 	ha->type = addr_type;
 	ha->refcount = 1;
 	ha->global_use = global;
-	ha->synced = false;
+	ha->synced = 0;
 	list_add_tail_rcu(&ha->list, &list->list);
 	list->count++;
 	return 0;
@@ -155,7 +155,7 @@ int __hw_addr_sync(struct netdev_hw_addr_list *to_list,
 					    addr_len, ha->type);
 			if (err)
 				break;
-			ha->synced = true;
+			ha->synced++;
 			ha->refcount++;
 		} else if (ha->refcount == 1) {
 			__hw_addr_del(to_list, ha->addr, addr_len, ha->type);
@@ -176,7 +176,7 @@ void __hw_addr_unsync(struct netdev_hw_addr_list *to_list,
 		if (ha->synced) {
 			__hw_addr_del(to_list, ha->addr,
 				      addr_len, ha->type);
-			ha->synced = false;
+			ha->synced--;
 			__hw_addr_del(from_list, ha->addr,
 				      addr_len, ha->type);
 		}