[ovs-dev] potential branch-2.5 GRE tunnel recreate issue

Sabyasachi Sengupta sabyasachi.sengupta at nokia.com
Tue Feb 9 19:13:43 UTC 2016


Hi Pravin,

I'm trying out GRE tunnel configure/deconfigure with branch-2.5 and master 
and saw that it was not able to configure the tunnel if it is recreated with 
openvswitch-dkms. My environment is Centos 6.6 (2.6.32-504 kernel). I 
noticed that as part of commit e23775, you added ifdef guard for 
netdev_unregister in compat/ip_tunnel.c for ip_tunnel_dellink, which is used 
by GRE.

+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,39)
+void rpl_ip_tunnel_dellink(struct net_device *dev, struct list_head *head)
+#else
+void rpl_ip_tunnel_dellink(struct net_device *dev)
+#endif
+{
+       struct ip_tunnel *tunnel = netdev_priv(dev);
+       struct ip_tunnel_net *itn;
+
+       itn = net_generic(tunnel->net, tunnel->ip_tnl_net_id);
+
+       ip_tunnel_del(itn, netdev_priv(dev));
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,39) <<<<<<<<<<<<<
+       unregister_netdevice_queue(dev, head);
+#endif
+}

I'm confused because I donot see any similar ifdef check in other tunnels, 
viz. vxlan etc and upon removing the ifdef, tunnel recreation goes through. 
I've noticed other symptoms of the issue, viz a kernel trace/hang like shown 
below when openvswitch is restarted with dkms loaded and GRE tunnels 
configured.

Pid: 8271, comm: rmmod Not tainted 2.6.32-504.16.2.el6.x86_64 #1 Supermicro 
X9SCI/X9SCA/X9SCI/X9SCA
RIP: 0010:[<ffffffff8146df08>]  [<ffffffff8146df08>] __rtnl_link_unregister+0x48/0xa0
  [<ffffffff8146df23>] ? __rtnl_link_unregister+0x63/0xa0
  [<ffffffff8146e42e>] ? rtnl_link_unregister+0x1e/0x30
  [<ffffffffa04f8235>] ? rpl_ipgre_fini+0x15/0x40 [openvswitch]
  [<ffffffffa04f1ee8>] ? ovs_vport_exit+0x18/0x30 [openvswitch]
  [<ffffffffa04e65a7>] ? dp_cleanup+0x77/0x90 [openvswitch]
  [<ffffffff810bd004>] ? sys_delete_module+0x194/0x260
  [<ffffffff8100b072>] ? system_call_fastpath+0x16/0x1b

There must be a reason for the ifdef guard, can you please fill me in on 
that?

Thanks,
Sabya





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