net: dsa: reference count the FDB addresses at the cross-chip notifier level

The same concerns expressed for host MDB entries are valid for host FDBs
just as well:

- in the case of multiple bridges spanning the same switch chip, deleting
  a host FDB entry that belongs to one bridge will result in breakage to
  the other bridge
- not deleting FDB entries across DSA links means that the switch's
  hardware tables will eventually run out, given enough wear&tear

So do the same thing and introduce reference counting for CPU ports and
DSA links using the same data structures as we have for MDB entries.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 2035d132682f..185629f27f80 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -348,6 +348,7 @@ static int dsa_port_setup(struct dsa_port *dp)
 	if (dp->setup)
 		return 0;
 
+	INIT_LIST_HEAD(&dp->fdbs);
 	INIT_LIST_HEAD(&dp->mdbs);
 
 	switch (dp->type) {
@@ -471,6 +472,11 @@ static void dsa_port_teardown(struct dsa_port *dp)
 		break;
 	}
 
+	list_for_each_entry_safe(a, tmp, &dp->fdbs, list) {
+		list_del(&a->list);
+		kfree(a);
+	}
+
 	list_for_each_entry_safe(a, tmp, &dp->mdbs, list) {
 		list_del(&a->list);
 		kfree(a);