net: Introduce net_rwsem to protect net_namespace_list

[linux-2.6-microblaze.git] / net / core / rtnetlink.c

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2d39497..e86b284 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -418,9 +418,11 @@ void __rtnl_link_unregister(struct rtnl_link_ops *ops)
 {
        struct net *net;
 
+       down_read(&net_rwsem);
        for_each_net(net) {
                __rtnl_kill_links(net, ops);
        }
+       up_read(&net_rwsem);
        list_del(&ops->list);
 }
 EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
@@ -438,6 +440,9 @@ static void rtnl_lock_unregistering_all(void)
        for (;;) {
                unregistering = false;
                rtnl_lock();
+               /* We held write locked pernet_ops_rwsem, and parallel
+                * setup_net() and cleanup_net() are not possible.
+                */
                for_each_net(net) {
                        if (net->dev_unreg_count > 0) {
                                unregistering = true;