All we need to take care of is using proper RCU list add/del primitives and inserting a synchronize_rcu() at one place to make sure the exit notifiers are run after everybody has stopped iterating the list. Signed-off-by: Johannes Berg --- include/net/net_namespace.h | 3 +++ net/core/net_namespace.c | 14 +++++++++++--- 2 files changed, 14 insertions(+), 3 deletions(-) --- wireless-testing.orig/include/net/net_namespace.h 2009-07-07 04:14:39.000000000 +0200 +++ wireless-testing/include/net/net_namespace.h 2009-07-07 12:17:17.000000000 +0200 @@ -211,6 +211,9 @@ static inline struct net *read_pnet(stru #define for_each_net(VAR) \ list_for_each_entry(VAR, &net_namespace_list, list) +#define for_each_net_rcu(VAR) \ + list_for_each_entry_rcu(VAR, &net_namespace_list, list) + #ifdef CONFIG_NET_NS #define __net_init #define __net_exit --- wireless-testing.orig/net/core/net_namespace.c 2009-07-07 03:43:35.000000000 +0200 +++ wireless-testing/net/core/net_namespace.c 2009-07-07 12:18:19.000000000 +0200 @@ -6,6 +6,7 @@ #include #include #include +#include #include #include @@ -127,7 +128,7 @@ static struct net *net_create(void) rv = setup_net(net); if (rv == 0) { rtnl_lock(); - list_add_tail(&net->list, &net_namespace_list); + list_add_tail_rcu(&net->list, &net_namespace_list); rtnl_unlock(); } mutex_unlock(&net_mutex); @@ -156,9 +157,16 @@ static void cleanup_net(struct work_stru /* Don't let anyone else find us. */ rtnl_lock(); - list_del(&net->list); + list_del_rcu(&net->list); rtnl_unlock(); + /* + * Another CPU might be rcu-iterating the list, wait for it. + * This needs to be before calling the exit() notifiers, so + * the rcu_barrier() below isn't sufficient alone. + */ + synchronize_rcu(); + /* Run all of the network namespace exit methods */ list_for_each_entry_reverse(ops, &pernet_list, list) { if (ops->exit) @@ -219,7 +227,7 @@ static int __init net_ns_init(void) panic("Could not setup the initial network namespace"); rtnl_lock(); - list_add_tail(&init_net.list, &net_namespace_list); + list_add_tail_rcu(&init_net.list, &net_namespace_list); rtnl_unlock(); mutex_unlock(&net_mutex); -- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html