datapath: use rx_handler_data pointer

This adds compatibility with kernel changeset
"bridge: use rx_handler_data pointer to store net_bridge_port pointer"
which was added between 2.6.35 and 2.6.36-rc1.

With this change it is now safe to (attempt to) insert both bridge and
datapath with newer (>=2.6.36) kernels, although whichever is inserted
second will fail to initialise on the call to netdev_rx_handler_register()

Signed-off-by: Simon Horman <horms@verge.net.au>
[Jesse: fixed merge conflicts in vport-netdev.c and netdevice.h]
Signed-off-by: Jesse Gross <jesse@nicira.com>

diff --git a/datapath/linux-2.6/compat-2.6/include/linux/if.h b/datapath/linux-2.6/compat-2.6/include/linux/if.h
index 0aa9ee3..2fd629c 100644 (file)
--- a/datapath/linux-2.6/compat-2.6/include/linux/if.h
+++ b/datapath/linux-2.6/compat-2.6/include/linux/if.h
@@ -10,4 +10,11 @@
 
 #endif /* linux kernel < 2.6.31 */
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
+/* XXX: Change to a unique value after merge */
+#define IFF_OVS_DATAPATH IFF_BRIDGE_PORT
+#else
+#define IFF_OVS_DATAPATH 0             /* no-op flag */
+#endif
+
 #endif

diff --git a/datapath/linux-2.6/compat-2.6/include/linux/netdevice.h b/datapath/linux-2.6/compat-2.6/include/linux/netdevice.h
index 29a7ccc..11d9f78 100644 (file)
--- a/datapath/linux-2.6/compat-2.6/include/linux/netdevice.h
+++ b/datapath/linux-2.6/compat-2.6/include/linux/netdevice.h
@@ -96,9 +96,13 @@ static inline int netdev_rx_handler_register(struct net_device *dev,
 {
        if (dev->br_port)
                return -EBUSY;
+       rcu_assign_pointer(dev->br_port, rx_handler_data);
        return 0;
 }
-static inline void netdev_rx_handler_unregister(struct net_device *dev) { }
+static inline void netdev_rx_handler_unregister(struct net_device *dev)
+{
+       rcu_assign_pointer(dev->br_port, NULL);
+}
 #endif
 
 #endif

diff --git a/datapath/vport-netdev.c b/datapath/vport-netdev.c
index e604535..e93a5ff 100644 (file)
--- a/datapath/vport-netdev.c
+++ b/datapath/vport-netdev.c
@@ -36,7 +36,7 @@ static struct sk_buff *netdev_frame_hook(struct sk_buff *skb)
        if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
                return skb;
 
-       vport = (struct vport *)rcu_dereference(skb->dev->br_port);
+       vport = netdev_get_vport(skb->dev);
 
        netdev_port_receive(vport, skb);
 
@@ -150,15 +150,14 @@ static int netdev_attach(struct vport *vport)
        struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
        int err;
 
-       rcu_assign_pointer(netdev_vport->dev->br_port,
-                          (struct net_bridge_port *)vport);
        err = netdev_rx_handler_register(netdev_vport->dev, netdev_frame_hook,
-                                        NULL);
+                                        vport);
        if (err)
                return err;
 
        dev_set_promiscuity(netdev_vport->dev, 1);
        dev_disable_lro(netdev_vport->dev);
+       netdev_vport->dev->priv_flags |= IFF_OVS_DATAPATH;
 
        return 0;
 }
@@ -167,8 +166,8 @@ static int netdev_detach(struct vport *vport)
 {
        struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
 
+       netdev_vport->dev->priv_flags &= ~IFF_OVS_DATAPATH;
        netdev_rx_handler_unregister(netdev_vport->dev);
-       rcu_assign_pointer(netdev_vport->dev->br_port, NULL);
        dev_set_promiscuity(netdev_vport->dev, -1);
 
        return 0;
@@ -304,7 +303,18 @@ static int netdev_send(struct vport *vport, struct sk_buff *skb)
 /* Returns null if this device is not attached to a datapath. */
 struct vport *netdev_get_vport(struct net_device *dev)
 {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
+       /* XXX: The bridge code may have registered the data.
+        * So check that the handler pointer is the datapath's.
+        * Once the merge is done and IFF_OVS_DATAPATH stops
+        * being the same value as IFF_BRIDGE_PORT the check can
+        * simply be netdev_vport->dev->priv_flags & IFF_OVS_DATAPATH. */
+       if (rcu_dereference(dev->rx_handler) != netdev_frame_hook)
+               return NULL;
+       return (struct vport *)rcu_dereference(dev->rx_handler_data);
+#else
        return (struct vport *)rcu_dereference(dev->br_port);
+#endif
 }
 
 struct vport_ops netdev_vport_ops = {
@@ -332,10 +342,12 @@ struct vport_ops netdev_vport_ops = {
        .send           = netdev_send,
 };
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,36)
 /*
- * Open vSwitch cannot safely coexist with the Linux bridge module on any
- * released version of Linux, because there is only a single bridge hook
- * function and only a single br_port member in struct net_device.
+ * In kernels earlier than 2.6.36, Open vSwitch cannot safely coexist with
+ * the Linux bridge module on any released version of Linux, because there
+ * is only a single bridge hook function and only a single br_port member
+ * in struct net_device.
  *
  * Declaring and exporting this symbol enforces mutual exclusion.  The bridge
  * module also exports the same symbol, so the module loader will refuse to
@@ -347,3 +359,4 @@ struct vport_ops netdev_vport_ops = {
  */
 typeof(br_should_route_hook) br_should_route_hook;
 EXPORT_SYMBOL(br_should_route_hook);
+#endif