Hi Hans,
So this approach has a fundamental problem, f->dst is changed without any synchronization
you cannot rely on it and thus you cannot account for these entries properly. We must be very
careful if we try to add any new synchronization not to affect performance as well.
More below...

quoted

@@ -319,6 +326,9 @@ static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f,
 	if (test_bit(BR_FDB_STATIC, &f->flags))
 		fdb_del_hw_addr(br, f->key.addr.addr);
 
+	if (test_bit(BR_FDB_ENTRY_LOCKED, &f->flags) && !test_bit(BR_FDB_OFFLOADED, &f->flags))
+		atomic_dec(&f->dst->locked_entry_cnt);

Sorry but you cannot do this for multiple reasons:
 - f->dst can be NULL
 - f->dst changes without any synchronization
 - there is no synchronization between fdb's flags and its ->dst

Cheers,
 Nik

Hi Nik,

if a port is decoupled from the bridge, the locked entries would of
course be invalid, so maybe if adding and removing a port is accounted
for wrt locked entries and the count of locked entries, would that not
work?

Best,
Hans