From ae33bc40c0d96d02f51a996482ea7e41c5152695 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 5 Nov 2008 16:00:02 -0800 Subject: net: Guaranetee the proper ordering of the loopback device. I was recently hunting a bug that occurred in network namespace cleanup. In looking at the code it became apparrent that we have and will continue to have cases where if we have anything going on in a network namespace there will be assumptions that the loopback device is present. Things like sending igmp unsubscribe messages when we bring down network devices invokes the routing code which assumes that at least the loopback driver is present. Therefore to avoid magic initcall ordering hackery that is hard to follow and hard to get right insert a call to register the loopback device directly from net_dev_init(). This guarantes that the loopback device is the first device registered and the last network device to go away. Signed-off-by: Eric W. Biederman Signed-off-by: David S. Miller --- net/core/dev.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index 9475f3e624a..811507c3980 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4904,6 +4904,18 @@ static int __init net_dev_init(void) if (register_pernet_subsys(&netdev_net_ops)) goto out; + /* The loopback device is special if any other network devices + * is present in a network namespace the loopback device must + * be present. Since we now dynamically allocate and free the + * loopback device ensure this invariant is maintained by + * keeping the loopback device as the first device on the + * list of network devices. Ensuring the loopback devices + * is the first device that appears and the last network device + * that disappears. + */ + if (register_pernet_device(&loopback_net_ops)) + goto out; + if (register_pernet_device(&default_device_ops)) goto out; -- cgit v1.2.3