[ovs-dev] [PATCH] compat: Allow IPv6 GRE/ERSPAN Tx when ip6_gre is loaded

Greg Rose gvrose8192 at gmail.com
Thu Jul 26 16:11:11 UTC 2018


When for some reason the built-in kernel ip6_gre module is loaded that
would prevent the openvswitch kernel driver from loading.  Even when
the built-in kernel ip6_gre module is loaded we can still perform
port mirroring via Tx.  Adjust the error handling and detect when
the ip6_gre kernel module is loaded and in that case still enable
IPv6 GRE/ERSPAN Tx.

Signed-off-by: Greg Rose <gvrose8192 at gmail.com>
---
 datapath/linux/compat/ip6_gre.c | 39 +++++++++++++++++++++++++++++++++------
 datapath/vport.c                | 17 +++++++++++++++--
 2 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/datapath/linux/compat/ip6_gre.c b/datapath/linux/compat/ip6_gre.c
index 0c88547..f532f21 100644
--- a/datapath/linux/compat/ip6_gre.c
+++ b/datapath/linux/compat/ip6_gre.c
@@ -65,6 +65,7 @@
 #define IP6_GRE_HASH_SIZE (1 << IP6_GRE_HASH_SIZE_SHIFT)
 
 static unsigned int ip6gre_net_id __read_mostly;
+static bool ip6_gre_loaded = false;
 struct ip6gre_net {
 	struct ip6_tnl __rcu *tunnels[4][IP6_GRE_HASH_SIZE];
 
@@ -2792,19 +2793,43 @@ int rpl_ip6gre_init(void)
 	int err;
 
 	err = register_pernet_device(&ip6gre_net_ops);
-	if (err < 0)
-		return err;
+	if (err < 0) {
+		if (err == -EEXIST)
+			goto ip6_gre_loaded;
+		else
+			goto out;
+	}
 
 	err = inet6_add_protocol(&ip6gre_protocol, IPPROTO_GRE);
 	if (err < 0) {
 		pr_info("%s: can't add protocol\n", __func__);
-		goto add_proto_failed;
+		if (err == -EBUSY) {
+			goto ip6_gre_loaded;
+		} else {
+			goto add_proto_failed;
+		}
 	}
 
 	pr_info("GRE over IPv6 tunneling driver\n");
 	ovs_vport_ops_register(&ovs_ip6gre_vport_ops);
 	ovs_vport_ops_register(&ovs_erspan6_vport_ops);
-	return 0;
+	return err;
+
+ip6_gre_loaded:
+	/* Since GRE only allows single receiver to be registerd,
+	 * we skip here so only gre transmit works, see:
+	 *
+	 * commit 9f57c67c379d88a10e8ad676426fee5ae7341b14
+	 * Author: Pravin B Shelar <pshelar at nicira.com>
+	 * Date:   Fri Aug 7 23:51:52 2015 -0700
+	 *     gre: Remove support for sharing GRE protocol hook
+	 *
+	 * OVS GRE receive part is disabled.
+	 */
+	pr_info("GRE TX only over IPv6 tunneling driver\n");
+	ip6_gre_loaded = true;
+	ovs_vport_ops_register(&ovs_ip6gre_vport_ops);
+	ovs_vport_ops_register(&ovs_erspan6_vport_ops);
 out:
 	return err;
 
@@ -2817,7 +2842,9 @@ void rpl_ip6gre_fini(void)
 {
 	ovs_vport_ops_unregister(&ovs_erspan6_vport_ops);
 	ovs_vport_ops_unregister(&ovs_ip6gre_vport_ops);
-	inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
-	unregister_pernet_device(&ip6gre_net_ops);
+	if (!ip6_gre_loaded) {
+		inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
+		unregister_pernet_device(&ip6gre_net_ops);
+	}
 }
 #endif /* USE_UPSTREAM_TUNNEL */
diff --git a/datapath/vport.c b/datapath/vport.c
index 28ddb86..e1b321f 100644
--- a/datapath/vport.c
+++ b/datapath/vport.c
@@ -43,6 +43,7 @@
 
 static LIST_HEAD(vport_ops_list);
 static bool compat_gre_loaded = false;
+static bool compat_ip6_tunnel_loaded = false;
 
 /* Protected by RCU read lock for reading, ovs_mutex for writing. */
 static struct hlist_head *dev_table;
@@ -81,11 +82,22 @@ int ovs_vport_init(void)
 		compat_gre_loaded = true;
 	}
 	err = ip6gre_init();
-	if (err)
+	if (err && err != -EEXIST) {
 		goto err_ip6gre;
+	} else {
+		if (err == -EEXIST) {
+			pr_warn("IPv6 GRE/ERSPAN Rx mode is not supported\n");
+			goto skip_ip6_tunnel_init;
+		}
+	}
+
 	err = ip6_tunnel_init();
 	if (err)
 		goto err_ip6_tunnel;
+	else
+		compat_ip6_tunnel_loaded = true;
+
+skip_ip6_tunnel_init:
 	err = geneve_init_module();
 	if (err)
 		goto err_geneve;
@@ -131,7 +143,8 @@ void ovs_vport_exit(void)
 	ovs_stt_cleanup_module();
 	vxlan_cleanup_module();
 	geneve_cleanup_module();
-	ip6_tunnel_cleanup();
+	if (compat_ip6_tunnel_loaded)
+		ip6_tunnel_cleanup();
 	ip6gre_fini();
 	lisp_cleanup_module();
 	kfree(dev_table);
-- 
1.8.3.1



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