4 files changed, 83 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 4ac1000b0ef2..165b9014379b 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h

@@ -510,6 +510,8 @@ enum {
 	IFLA_BR_VLAN_STATS_PER_PORT,
 	IFLA_BR_MULTI_BOOLOPT,
 	IFLA_BR_MCAST_QUERIER_STATE,
+	IFLA_BR_FDB_CUR_LEARNED_ENTRIES,
+	IFLA_BR_FDB_MAX_LEARNED_ENTRIES,
 	__IFLA_BR_MAX,
 };
 

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index ac1dc8723b9c..bc61d1fd5fcf 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c

@@ -301,6 +301,38 @@ static void fdb_add_hw_addr(struct net_bridge *br, const unsigned char *addr)
 	}
 }
 
+/* Set a FDB flag that implies the entry was not learned, and account
+ * for changes in the learned status.
+ */
+static void __fdb_set_flag_not_learned(struct net_bridge *br,
+				       struct net_bridge_fdb_entry *fdb,
+				       long nr)
+{
+	WARN_ON_ONCE(!(BIT(nr) & BR_FDB_NOT_LEARNED_MASK));
+
+	/* learned before, but we set a flag that implies it's manually added */
+	if (!(fdb->flags & BR_FDB_NOT_LEARNED_MASK))
+		br->fdb_cur_learned_entries--;
+	set_bit(nr, &fdb->flags);
+}
+
+/* Set a FDB flag that implies the entry was not learned, and account
+ * for changes in the learned status.
+ *
+ * This function takes a lock, so ensure it is not called in the fast
+ * path.
+ */
+static void fdb_set_flag_not_learned(struct net_bridge *br,
+				     struct net_bridge_fdb_entry *fdb,
+				     long nr)
+{
+	spin_lock_bh(&br->hash_lock);
+
+	__fdb_set_flag_not_learned(br, fdb, nr);
+
+	spin_unlock_bh(&br->hash_lock);
+}
+
 /* When a static FDB entry is deleted, the HW address from that entry is
  * also removed from the bridge private HW address list and updates all
  * the ports with needed information.

@@ -321,6 +353,8 @@ static void fdb_del_hw_addr(struct net_bridge *br, const unsigned char *addr)
 static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f,
 		       bool swdev_notify)
 {
+	bool learned = !(f->flags & BR_FDB_NOT_LEARNED_MASK);
+
 	trace_fdb_delete(br, f);
 
 	if (test_bit(BR_FDB_STATIC, &f->flags))

@@ -329,11 +363,16 @@ static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f,
 	hlist_del_init_rcu(&f->fdb_node);
 	rhashtable_remove_fast(&br->fdb_hash_tbl, &f->rhnode,
 			       br_fdb_rht_params);
+	br->fdb_cur_learned_entries -= learned;
 	fdb_notify(br, f, RTM_DELNEIGH, swdev_notify);
 	call_rcu(&f->rcu, fdb_rcu_free);
 }
 
-/* Delete a local entry if no other port had the same address. */
+/* Delete a local entry if no other port had the same address.
+ *
+ * This function should only be called on entries with BR_FDB_LOCAL set,
+ * so clear_bit never removes the last bit in BR_FDB_NOT_LEARNED_MASK.
+ */
 static void fdb_delete_local(struct net_bridge *br,
 			     const struct net_bridge_port *p,
 			     struct net_bridge_fdb_entry *f)

@@ -390,6 +429,11 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
 {
 	struct net_bridge_fdb_entry *fdb;
 	int err;
+	bool learned = !(flags & BR_FDB_NOT_LEARNED_MASK);

+		return NULL;
 
 	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 	if (!fdb)

@@ -409,6 +453,8 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
 
 	hlist_add_head_rcu(&fdb->fdb_node, &br->fdb_list);
 
+	br->fdb_cur_learned_entries += learned;

+
 	return fdb;
 }
 

@@ -894,7 +940,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 			}
 
 			if (unlikely(test_bit(BR_FDB_ADDED_BY_USER, &flags)))
-				set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
+				fdb_set_flag_not_learned(br, fdb, BR_FDB_ADDED_BY_USER);
 			if (unlikely(fdb_modified)) {
 				trace_br_fdb_update(br, source, addr, vid, flags);
 				fdb_notify(br, fdb, RTM_NEWNEIGH, true);

@@ -1070,6 +1116,8 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 			modified = true;
 		}
 
+		if (!(fdb->flags & BR_FDB_NOT_LEARNED_MASK))
+			br->fdb_cur_learned_entries--;
 		set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 	}
 

@@ -1440,10 +1488,10 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
 		}
 
 		if (swdev_notify)
-			set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
+			__fdb_set_flag_not_learned(br, fdb, BR_FDB_ADDED_BY_USER);
 
 		if (!p)
-			set_bit(BR_FDB_LOCAL, &fdb->flags);
+			__fdb_set_flag_not_learned(br, fdb, BR_FDB_LOCAL);
 
 		if (modified)
 			fdb_notify(br, fdb, RTM_NEWNEIGH, swdev_notify);

@@ -1508,3 +1556,14 @@ void br_fdb_clear_offload(const struct net_device *dev, u16 vid)
 	spin_unlock_bh(&p->br->hash_lock);
 }
 EXPORT_SYMBOL_GPL(br_fdb_clear_offload);
+
+u32 br_fdb_get_cur_learned_entries(struct net_bridge *br)
+{
+	u32 ret;
+
+	spin_lock_bh(&br->hash_lock);
+	ret = br->fdb_cur_learned_entries;

+	spin_unlock_bh(&br->hash_lock);
+
+	return ret;
+}

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 05c5863d2e20..954c468d52ec 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c

@@ -1527,6 +1527,12 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
 			return err;
 	}
 
+	if (data[IFLA_BR_FDB_MAX_LEARNED_ENTRIES]) {

+		u32 val = nla_get_u32(data[IFLA_BR_FDB_MAX_LEARNED_ENTRIES]);
+
+		br->fdb_max_learned_entries = val;
+	}
+
 	return 0;
 }
 

@@ -1581,6 +1587,8 @@ static size_t br_get_size(const struct net_device *brdev)
 	       nla_total_size_64bit(sizeof(u64)) + /* IFLA_BR_TOPOLOGY_CHANGE_TIMER */
 	       nla_total_size_64bit(sizeof(u64)) + /* IFLA_BR_GC_TIMER */
 	       nla_total_size(ETH_ALEN) +       /* IFLA_BR_GROUP_ADDR */
+	       nla_total_size(sizeof(u32)) +    /* IFLA_BR_FDB_CUR_LEARNED_ENTRIES */
+	       nla_total_size(sizeof(u32)) +    /* IFLA_BR_FDB_MAX_LEARNED_ENTRIES */
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	       nla_total_size(sizeof(u8)) +     /* IFLA_BR_MCAST_ROUTER */
 	       nla_total_size(sizeof(u8)) +     /* IFLA_BR_MCAST_SNOOPING */

@@ -1620,6 +1628,7 @@ static int br_fill_info(struct sk_buff *skb, const struct net_device *brdev)
 	u32 stp_enabled = br->stp_enabled;
 	u16 priority = (br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1];
 	u8 vlan_enabled = br_vlan_enabled(br->dev);
+	u32 fdb_cur_learned_entries = br_fdb_get_cur_learned_entries(br);
 	struct br_boolopt_multi bm;
 	u64 clockval;
 

@@ -1656,7 +1665,9 @@ static int br_fill_info(struct sk_buff *skb, const struct net_device *brdev)
 	    nla_put_u8(skb, IFLA_BR_TOPOLOGY_CHANGE_DETECTED,
 		       br->topology_change_detected) ||
 	    nla_put(skb, IFLA_BR_GROUP_ADDR, ETH_ALEN, br->group_addr) ||
-	    nla_put(skb, IFLA_BR_MULTI_BOOLOPT, sizeof(bm), &bm))
+	    nla_put(skb, IFLA_BR_MULTI_BOOLOPT, sizeof(bm), &bm) ||
+	    nla_put_u32(skb, IFLA_BR_FDB_CUR_LEARNED_ENTRIES, fdb_cur_learned_entries) ||
+	    nla_put_u32(skb, IFLA_BR_FDB_MAX_LEARNED_ENTRIES, br->fdb_max_learned_entries))
 		return -EMSGSIZE;
 
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 2119729ded2b..df079191479e 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h

@@ -275,6 +275,8 @@ enum {
 	BR_FDB_LOCKED,
 };
 
+#define BR_FDB_NOT_LEARNED_MASK (BIT(BR_FDB_LOCAL) | BIT(BR_FDB_ADDED_BY_USER))
+
 struct net_bridge_fdb_key {
 	mac_addr addr;
 	u16 vlan_id;

@@ -553,6 +555,9 @@ struct net_bridge {
 	struct kobject			*ifobj;
 	u32				auto_cnt;
 
+	u32				fdb_max_learned_entries;
+	u32				fdb_cur_learned_entries;
+
 #ifdef CONFIG_NET_SWITCHDEV
 	/* Counter used to make sure that hardware domains get unique
 	 * identifiers in case a bridge spans multiple switchdev instances.

@@ -838,6 +843,7 @@ int br_fdb_external_learn_del(struct net_bridge *br, struct net_bridge_port *p,
 			      bool swdev_notify);
 void br_fdb_offloaded_set(struct net_bridge *br, struct net_bridge_port *p,
 			  const unsigned char *addr, u16 vid, bool offloaded);
+u32 br_fdb_get_cur_learned_entries(struct net_bridge *br);
 
 /* br_forward.c */
 enum br_pkt_type {

-- 
2.40.1