[PATCH 4/7] bridge: Automatically manage port promiscuous mode.

[Vlad Yasevich <vyasevic@xxxxxxxxxx>]

When there is only 1 flooding port, this port is programmed
with all the address the bridge accumulated.  This allows
us to place this port into non-promiscuous mode.
At other times, all ports are set as promiscuous.  To help
track whether the bridge set the mode or not, a new
flag is introduced.

Signed-off-by: Vlad Yasevich <vyasevic@xxxxxxxxxx>
---
 net/bridge/br_if.c      | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
 net/bridge/br_private.h |  1 +
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index e782c2e..51df642 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -136,7 +136,7 @@ static void del_nbp(struct net_bridge_port *p)
 
 	sysfs_remove_link(br->ifobj, p->dev->name);
 
-	dev_set_promiscuity(dev, -1);
+	dev_set_allmulti(dev, -1);
 
 	spin_lock_bh(&br->lock);
 	br_stp_disable_port(p);
@@ -359,7 +359,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
 
 	call_netdevice_notifiers(NETDEV_JOIN, dev);
 
-	err = dev_set_promiscuity(dev, 1);
+	err = dev_set_allmulti(dev, 1);
 	if (err)
 		goto put_back;
 
@@ -465,6 +465,48 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 	return 0;
 }
 
+static int br_port_set_promisc(struct net_bridge_port *p)
+{
+	int err = 0;
+
+	if (p->flags & BR_PROMISC)
+		return err;
+
+	err = dev_set_promiscuity(p->dev, 1);
+	if (err)
+		return err;
+
+	p->flags |= BR_PROMISC;
+	return err;
+}
+
+static void br_port_clear_promisc(struct net_bridge_port *p)
+{
+	if (!(p->flags & BR_PROMISC))
+		return;
+
+	dev_set_promiscuity(p->dev, -1);
+	p->flags &= ~BR_PROMISC;
+}
+
+/* When a port is added or removed or when the flooding status of
+ * the port changes, this function is called to automatically mange
+ * promiscuity setting of all the bridge ports.  We are always called
+ * under RTNL so can skip using rcu primitives.
+ */
+static void br_manage_promisc(struct net_bridge *br)
+{
+	struct net_bridge_port *p;
+
+	list_for_each_entry(p, &br->port_list, list) {
+		if (!br_port_exists(p->dev) ||
+		    (br->n_flood_ports == 1 && br->c_flood_port == p))
+			br_port_clear_promisc(p);
+		else
+			br_port_set_promisc(p);
+	}
+}
+
 static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br)
 {
 	/* Increment the number of  flooding ports, and if we
@@ -475,6 +517,7 @@ static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br)
 		br->c_flood_port = p;
 
 	br_fdb_addrs_sync(br);
+	br_manage_promisc(br);
 }
 
 static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br)
@@ -502,6 +545,7 @@ static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br)
 			}
 		}
 	}
+	br_manage_promisc(br);
 }
 
 void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 40a6927..6670cb3 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -174,6 +174,7 @@ struct net_bridge_port
 #define BR_ADMIN_COST		0x00000010
 #define BR_LEARNING		0x00000020
 #define BR_FLOOD		0x00000040
+#define BR_PROMISC		0x00000080
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	struct bridge_mcast_query	ip4_query;
-- 
1.8.5.3