bridge: add API to notify bridge driver of learned FBD on offloaded device

When the swdev device learns a new mac/vlan on a port, it sends some async
notification to the driver and the driver installs an FDB in the device.
To give a holistic system view, the learned mac/vlan should be reflected
in the bridge's FBD table, so the user, using normal iproute2 cmds, can view
what is currently learned by the device.  This API on the bridge driver gives
a way for the swdev driver to install an FBD entry in the bridge FBD table.
(And remove one).

This is equivalent to the device running these cmds:

  bridge fdb [add|del] <mac> dev <dev> vid <vlan id> master

This patch needs some extra eyeballs for review, in paricular around the
locking and contexts.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 92 insertions, 2 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index b1be971eb06c..cc36e59db7d7 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -481,6 +481,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
                 fdb->is_local = 0;
                 fdb->is_static = 0;
                 fdb->added_by_user = 0;
+                fdb->added_by_external_learn = 0;
                 fdb->updated = fdb->used = jiffies;
                 hlist_add_head_rcu(&fdb->hlist, head);
         }
@@ -613,7 +614,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
         ndm->ndm_family  = AF_BRIDGE;
         ndm->ndm_pad1    = 0;
         ndm->ndm_pad2    = 0;
-        ndm->ndm_flags   = 0;
+        ndm->ndm_flags   = fdb->added_by_external_learn ? NTF_EXT_LEARNED : 0;
         ndm->ndm_type    = 0;
         ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
         ndm->ndm_state   = fdb_to_nud(fdb);
@@ -983,3 +984,91 @@ void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p)
                 }
         }
 }
+
+int br_fdb_external_learn_add(struct net_device *dev,
+                              const unsigned char *addr, u16 vid)
+{
+        struct net_bridge_port *p;
+        struct net_bridge *br;
+        struct hlist_head *head;
+        struct net_bridge_fdb_entry *fdb;
+        int err = 0;
+
+        rtnl_lock();
+
+        p = br_port_get_rtnl(dev);
+        if (!p) {
+                pr_info("bridge: %s not a bridge port\n", dev->name);
+                err = -EINVAL;
+                goto err_rtnl_unlock;
+        }
+
+        br = p->br;
+
+        spin_lock_bh(&br->hash_lock);
+
+        head = &br->hash[br_mac_hash(addr, vid)];
+        fdb = fdb_find(head, addr, vid);
+        if (!fdb) {
+                fdb = fdb_create(head, p, addr, vid);
+                if (!fdb) {
+                        err = -ENOMEM;
+                        goto err_unlock;
+                }
+                fdb->added_by_external_learn = 1;
+                fdb_notify(br, fdb, RTM_NEWNEIGH);
+        } else if (fdb->added_by_external_learn) {
+                /* Refresh entry */
+                fdb->updated = fdb->used = jiffies;
+        } else if (!fdb->added_by_user) {
+                /* Take over SW learned entry */
+                fdb->added_by_external_learn = 1;
+                fdb->updated = jiffies;
+                fdb_notify(br, fdb, RTM_NEWNEIGH);
+        }
+
+err_unlock:
+        spin_unlock_bh(&br->hash_lock);
+err_rtnl_unlock:
+        rtnl_unlock();
+
+        return err;
+}
+EXPORT_SYMBOL(br_fdb_external_learn_add);
+
+int br_fdb_external_learn_del(struct net_device *dev,
+                              const unsigned char *addr, u16 vid)
+{
+        struct net_bridge_port *p;
+        struct net_bridge *br;
+        struct hlist_head *head;
+        struct net_bridge_fdb_entry *fdb;
+        int err = 0;
+
+        rtnl_lock();
+
+        p = br_port_get_rtnl(dev);
+        if (!p) {
+                pr_info("bridge: %s not a bridge port\n", dev->name);
+                err = -EINVAL;
+                goto err_rtnl_unlock;
+        }
+
+        br = p->br;
+
+        spin_lock_bh(&br->hash_lock);
+
+        head = &br->hash[br_mac_hash(addr, vid)];
+        fdb = fdb_find(head, addr, vid);
+        if (fdb && fdb->added_by_external_learn)
+                fdb_delete(br, fdb);
+        else
+                err = -ENOENT;
+
+        spin_unlock_bh(&br->hash_lock);
+err_rtnl_unlock:
+        rtnl_unlock();
+
+        return err;
+}
+EXPORT_SYMBOL(br_fdb_external_learn_del);
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 1b529da8234d..cc36fb3efbdd 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -100,7 +100,8 @@ struct net_bridge_fdb_entry
         mac_addr                        addr;
         unsigned char                   is_local:1,
                                         is_static:1,
-                                        added_by_user:1;
+                                        added_by_user:1,
+                                        added_by_external_learn:1;
         __u16                           vlan_id;
 };