Re: Move interface across network namespaces

Renato Westphal [off-list ref] writes:

I forgot to mention that I'm using kernel v2.6.35 (with a lot of
backports). For future reference, the commit 3b27e105550f7c4a ("netns:
keep vlan slaves on master netns move", merged into v2.6.37-rc1) fixes
this problem.

Which makes me silly as I now remember reviewing that patch.

quoted

quoted

quoted

* The target network namespace sends a RTM_NEWLINK netlink message
when an interface is moved to it. In the other hand, the source
network namespace doesn't sends a RTM_DELLINK message when an
interface is moved from it. This is very annoying because user space
applications (such as zebra) can't detect some interface moving
operations and then get into an inconsistent state. Anyone knows if
there's a workaround for this?

Not getting RTM_DELLINK is a bug.  The device registration and
unregistration code has changed since dev_change_net_namespace was
written and apparently one of the changes failed to update
dev_change_net_namespace.

Good, that makes a lot more sense. In the kernel 2.6.32.43 the
RTM_DELLINK netlink message is sent when a network interface is moved
from a network namespace. The same doesn't happens in the kernel
2.6.35.13. I'll try to isolate the problem some more.

Well, this regression was introduced by commit a2835763e130c343ac,
which was merged into v2.6.34. Reverting parts of this commit makes
the problem go away but breaks the support of "specifying device flags
during device creation". I don't know the best way to fix this... any
ideas?

Everything going through dev_change_net_namespace already needs to be
in the initialized state.  So it looks like we just need to do:

Does the patch below work for you?

Eric

---

diff --git a/net/core/dev.c b/net/core/dev.c
index 17d67b5..bfbde69 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c

@@ -6108,6 +6108,8 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
 	call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
 	call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
 
+	rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
+
 	/*
 	 *	Flush the unicast and multicast chains
 	 */