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netdev: Fix netdev_open() to adhere to class type if given

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When trying to configure a system port as type=internal it could start
an infinite port creation loop. When this happens you will see the
following log messages:

2017-06-01T09:00:17.900Z|02813|dpif|WARN|system@ovs-system: failed to add ve01_1 as port: File exists
2017-06-01T09:00:17.900Z|02814|bridge|WARN|could not add network device ve01_1 to ofproto (File exists)
2017-06-01T09:00:17.907Z|02815|bridge|INFO|bridge bzb: added interface ve01_1 on port 2
2017-06-01T09:00:17.909Z|02816|bridge|INFO|bridge bzb: deleted interface ve01_1 on port 2
2017-06-01T09:00:17.914Z|02817|dpif|WARN|system@ovs-system: failed to add ve01_1 as port: File exists
2017-06-01T09:00:17.914Z|02818|bridge|WARN|could not add network device ve01_1 to ofproto (File exists)
2017-06-01T09:00:17.921Z|02819|bridge|INFO|bridge bzb: added interface ve01_1 on port 3
2017-06-01T09:00:17.923Z|02820|bridge|INFO|bridge bzb: deleted interface ve01_1 on port 3
2017-06-01T09:00:17.929Z|02821|dpif|WARN|system@ovs-system: failed to add ve01_1 as port: File exists
2017-06-01T09:00:17.929Z|02822|bridge|WARN|could not add network device ve01_1 to ofproto (File exists)
2017-06-01T09:00:17.936Z|02823|bridge|INFO|bridge bzb: added interface ve01_1 on port 4
...
...

This is how to replicate it:

  ip link add name ve01_1 type veth peer name ve01_2
  ovs-vsctl add-br bzb
  ovs-vsctl add-port bzb ve01_1
  ovs-vsctl set interface ve01_1 type=internal
  ip link set dev ve01_1 up
  ip link set dev ve01_2 up

When changing the type to internal, the async configuration logic get
triggered and because the type has changed it will delete the
interface and the ofproto port. Next it will call iface_do_create() to
re-create the interface as internal. Because we just deleted the
interface netdev_open() will try to recreate it as internal.

However this will fail with EEXIST as a system interface already
exists withe the name.

Up till here all is fine...

Now some ipv6 route change comes along for the ve01_1 interface, and
the route infrastructure will call netdev_open(). This will create the
interface of type system.

Next the configuration verify process gets triggered due to
if_notifier_changed() being true. We now retry the above, but because
the interface exists (although in the system class) it will use it,
and create the interface successfully.

This triggers another if notification, causing yet another config
update, and because the system != internal reconfiguration happens and
it start from the top...

So the fix as presented below is causing netdev_open() only to return
the existing device for the class type requested (if the type is
specified).

Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
This commit is contained in:
Eelco Chaudron
2017-06-01 14:38:09 +02:00
committed by Ben Pfaff
parent f651d4ac4b
commit 67ac844b55
1 changed files with 2 additions and 0 deletions
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2
lib/netdev.c
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@@ -411,6 +411,8 @@ netdev_open(const char *name, const char *type, struct netdev **netdevp)
name, type);
error = EAFNOSUPPORT;
}
} else if (type && type[0] && strcmp(type, netdev->netdev_class->type)) {
error = EEXIST;
} else {
error = 0;
}