datapath: Fix mutual exclusion with bridge on Linux 2.6.27+.

[sliver-openvswitch.git] / datapath / datapath.c

diff --git a/datapath/datapath.c b/datapath/datapath.c
index e927b24..b8ef104 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -1582,6 +1582,8 @@ struct file_operations openvswitch_fops = {
 };
 
 static int major;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
 static struct llc_sap *dp_stp_sap;
 
 static int dp_stp_rcv(struct sk_buff *skb, struct net_device *dev,
@@ -1594,12 +1596,8 @@ static int dp_stp_rcv(struct sk_buff *skb, struct net_device *dev,
        return 0;
 }
 
-static int __init dp_init(void)
+static int dp_avoid_bridge_init(void)
 {
-       int err;
-
-       printk("Open vSwitch %s, built "__DATE__" "__TIME__"\n", VERSION BUILDNR);
-
        /* Register to receive STP packets because the bridge module also
         * attempts to do so.  Since there can only be a single listener for a
         * given protocol, this provides mutual exclusion against the bridge
@@ -1610,6 +1608,43 @@ static int __init dp_init(void)
                printk(KERN_ERR "openvswitch: can't register sap for STP (probably the bridge module is loaded)\n");
                return -EADDRINUSE;
        }
+       return 0;
+}
+
+static void dp_avoid_bridge_exit(void)
+{
+       llc_sap_put(dp_stp_sap);
+}
+#else  /* Linux 2.6.27 or later. */
+static int dp_avoid_bridge_init(void)
+{
+       /* Linux 2.6.27 introduces a way for multiple clients to register for
+        * STP packets, which interferes with what we try to do above.
+        * Instead, just check whether there's a bridge hook defined.  This is
+        * not as safe--the bridge module is willing to load over the top of
+        * us--but it provides a little bit of protection. */
+       if (br_handle_frame_hook) {
+               printk(KERN_ERR "openvswitch: bridge module is loaded, cannot load over it\n");
+               return -EADDRINUSE;
+       }
+       return 0;
+}
+
+static void dp_avoid_bridge_exit(void)
+{
+       /* Nothing to do. */
+}
+#endif /* Linux 2.6.27 or later */
+
+static int __init dp_init(void)
+{
+       int err;
+
+       printk("Open vSwitch %s, built "__DATE__" "__TIME__"\n", VERSION BUILDNR);
+
+       err = dp_avoid_bridge_init();
+       if (err)
+               return err;
 
        err = flow_init();
        if (err)
@@ -1644,7 +1679,7 @@ static void dp_cleanup(void)
        unregister_netdevice_notifier(&dp_device_notifier);
        flow_exit();
        br_handle_frame_hook = NULL;
-       llc_sap_put(dp_stp_sap);
+       dp_avoid_bridge_exit();
 }
 
 module_init(dp_init);