net_ns: add __rcu annotations

add __rcu annotation to (struct net)->gen, and use
rcu_dereference_protected() in net_assign_generic()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 4 insertions, 2 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 65af9a07cf76..1bf812b21fb7 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -88,7 +88,7 @@ struct net {
 #ifdef CONFIG_WEXT_CORE
         struct sk_buff_head     wext_nlevents;
 #endif
-        struct net_generic      *gen;
+        struct net_generic __rcu        *gen;
 
         /* Note : following structs are cache line aligned */
 #ifdef CONFIG_XFRM
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index c988e685433a..3f860261c5ee 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -42,7 +42,9 @@ static int net_assign_generic(struct net *net, int id, void *data)
         BUG_ON(!mutex_is_locked(&net_mutex));
         BUG_ON(id == 0);
 
-        ng = old_ng = net->gen;
+        old_ng = rcu_dereference_protected(net->gen,
+                                           lockdep_is_held(&net_mutex));
+        ng = old_ng;
         if (old_ng->len >= id)
                 goto assign;