datapath: Use openvswitch_handle_frame hook in >=RHEL6.4 to live side…

… by side with bridging

Due to the missing register rx_handler API in the kernel RHEL6 is
based on, the datapath currently falls back to using the bridging
hook with the consequence that bridging and OVS cannot be used in
parallel on any RHEL6 release.

For this purpose, >=RHEL6.4 releases provide a special rx frame hook
to be used by OVS. It captures frames at the same location in the
stack as the rx_handler would do in more recent kernel releases. In
order to store the vport pointer, the net_device's ax25_ptr field is
utilized under the assumption that an AX25 device will never be
attached to an OVS bridge.

Signed-off-by: Thomas Graf <[email protected]>
Signed-off-by: Jesse Gross <[email protected]>

acinclude.m4

@@ -273,6 +273,9 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/if_vlan.h], [ADD_ALL_VLANS_CMD],
                   [OVS_DEFINE([HAVE_VLAN_BUG_WORKAROUND])])
 
+  OVS_GREP_IFELSE([$KSRC/include/linux/openvswitch.h], [openvswitch_handle_frame_hook],
+                  [OVS_DEFINE([HAVE_RHEL_OVS_HOOK])])
+
   OVS_CHECK_LOG2_H
 
   if cmp -s datapath/linux/kcompat.h.new \

datapath/vport-netdev.c

@@ -45,6 +45,12 @@ MODULE_PARM_DESC(vlan_tso, "Enable TSO for VLAN packets");
 #define vlan_tso true
 #endif
 
+#ifdef HAVE_RHEL_OVS_HOOK
+static atomic_t nr_bridges = ATOMIC_INIT(0);
+
+extern struct sk_buff *(*openvswitch_handle_frame_hook)(struct sk_buff *skb);
+#endif
+
 static void netdev_port_receive(struct vport *vport, struct sk_buff *skb);
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,39)
@@ -63,7 +69,8 @@ static rx_handler_result_t netdev_frame_hook(struct sk_buff **pskb)
 
 	return RX_HANDLER_CONSUMED;
 }
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36) || \
+      defined HAVE_RHEL_OVS_HOOK
 /* Called with rcu_read_lock and bottom-halves disabled. */
 static struct sk_buff *netdev_frame_hook(struct sk_buff *skb)
 {
@@ -105,7 +112,8 @@ static int netdev_frame_hook(struct net_bridge_port *p, struct sk_buff **pskb)
 #error
 #endif
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36) || \
+    defined HAVE_RHEL_OVS_HOOK
 static int netdev_init(void) { return 0; }
 static void netdev_exit(void) { }
 #else
@@ -153,10 +161,16 @@ static struct vport *netdev_create(const struct vport_parms *parms)
 	}
 
 	rtnl_lock();
+#ifdef HAVE_RHEL_OVS_HOOK
+	rcu_assign_pointer(netdev_vport->dev->ax25_ptr, vport);
+	atomic_inc(&nr_bridges);
+	rcu_assign_pointer(openvswitch_handle_frame_hook, netdev_frame_hook);
+#else
 	err = netdev_rx_handler_register(netdev_vport->dev, netdev_frame_hook,
 					 vport);
 	if (err)
 		goto error_unlock;
+#endif
 
 	dev_set_promiscuity(netdev_vport->dev, 1);
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
@@ -167,7 +181,9 @@ static struct vport *netdev_create(const struct vport_parms *parms)
 
 	return vport;
 
+#ifndef HAVE_RHEL_OVS_HOOK
 error_unlock:
+#endif
 	rtnl_unlock();
 error_put:
 	dev_put(netdev_vport->dev);
@@ -182,6 +198,12 @@ static void free_port_rcu(struct rcu_head *rcu)
 	struct netdev_vport *netdev_vport = container_of(rcu,
 					struct netdev_vport, rcu);
 
+#ifdef HAVE_RHEL_OVS_HOOK
+	rcu_assign_pointer(netdev_vport->dev->ax25_ptr, NULL);
+
+	if (atomic_dec_and_test(&nr_bridges))
+		rcu_assign_pointer(openvswitch_handle_frame_hook, NULL);
+#endif
 	dev_put(netdev_vport->dev);
 	ovs_vport_free(vport_from_priv(netdev_vport));
 }
@@ -351,13 +373,18 @@ static int netdev_send(struct vport *vport, struct sk_buff *skb)
 /* Returns null if this device is not attached to a datapath. */
 struct vport *ovs_netdev_get_vport(struct net_device *dev)
 {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36) || \
+    defined HAVE_RHEL_OVS_HOOK
 #if IFF_OVS_DATAPATH != 0
 	if (likely(dev->priv_flags & IFF_OVS_DATAPATH))
 #else
 	if (likely(rcu_access_pointer(dev->rx_handler) == netdev_frame_hook))
 #endif
+#ifdef HAVE_RHEL_OVS_HOOK
+		return (struct vport *)rcu_dereference_rtnl(dev->ax25_ptr);
+#else
 		return (struct vport *)rcu_dereference_rtnl(dev->rx_handler_data);
+#endif
 	else
 		return NULL;
 #else
@@ -377,7 +404,8 @@ const struct vport_ops ovs_netdev_vport_ops = {
 	.send		= netdev_send,
 };
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,36)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,36) && \
+    !defined HAVE_RHEL_OVS_HOOK
 /*
  * Enforces, mutual exclusion with the Linux bridge module, by declaring and
  * exporting br_should_route_hook.  Because the bridge module also exports the