From 4edf547b4d0f886acf5aa5a0c8f8edbaff280830 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 15 Jul 2009 06:16:34 +0000 Subject: net: explain netns notifiers a little better Eric explained this to me -- and afterwards the comment made sense, but not before. Add the the critical point about interfaces having to be gone from the netns before subsys notifiers are called. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller --- include/net/net_namespace.h | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'include') diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 5c5136fceea8..a1202841aadd 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -239,13 +239,15 @@ struct pernet_operations { * needs per network namespace operations use device pernet operations, * otherwise use pernet subsys operations. * - * This is critically important. Most of the network code cleanup - * runs with the assumption that dev_remove_pack has been called so no - * new packets will arrive during and after the cleanup functions have - * been called. dev_remove_pack is not per namespace so instead the - * guarantee of no more packets arriving in a network namespace is - * provided by ensuring that all network devices and all sockets have - * left the network namespace before the cleanup methods are called. + * Network interfaces need to be removed from a dying netns _before_ + * subsys notifiers can be called, as most of the network code cleanup + * (which is done from subsys notifiers) runs with the assumption that + * dev_remove_pack has been called so no new packets will arrive during + * and after the cleanup functions have been called. dev_remove_pack + * is not per namespace so instead the guarantee of no more packets + * arriving in a network namespace is provided by ensuring that all + * network devices and all sockets have left the network namespace + * before the cleanup methods are called. * * For the longest time the ipv4 icmp code was registered as a pernet * device which caused kernel oops, and panics during network -- cgit v1.2.1