[BRIDGE]: set features based on enslaved devices

Make features of the bridge pseudo-device be a subset of the underlying
devices.  Motivated by Xen and others who use bridging to do failover.

Signed-off-by: Catalin BOIE <catab at umrella.ro>
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 0 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 69872bf3b87..91bb895375f 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -314,6 +314,28 @@ int br_min_mtu(const struct net_bridge *br)
         return mtu;
 }
 
+/*
+ * Recomputes features using slave's features
+ */
+void br_features_recompute(struct net_bridge *br)
+{
+        struct net_bridge_port *p;
+        unsigned long features, checksum;
+
+        features = NETIF_F_SG | NETIF_F_FRAGLIST 
+                | NETIF_F_HIGHDMA | NETIF_F_TSO;
+        checksum = NETIF_F_IP_CSUM;     /* least commmon subset */
+
+        list_for_each_entry(p, &br->port_list, list) {
+                if (!(p->dev->features 
+                      & (NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM)))
+                        checksum = 0;
+                features &= p->dev->features;
+        }
+
+        br->dev->features = features | checksum | NETIF_F_LLTX;
+}
+
 /* called with RTNL */
 int br_add_if(struct net_bridge *br, struct net_device *dev)
 {
@@ -368,6 +390,7 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 
         spin_lock_bh(&br->lock);
         br_stp_recalculate_bridge_id(br);
+        br_features_recompute(br);
         spin_unlock_bh(&br->lock);
 
         return 0;