netns: add dummy struct inside "struct net_generic"

This is precursor to fixing "[id - 1]" bloat inside net_generic().

Name "s" is chosen to complement name "u" often used for dummy unions.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/netns/generic.h b/include/net/netns/generic.h
index d315786..65ccce6 100644 (file)
--- a/include/net/netns/generic.h
+++ b/include/net/netns/generic.h
@@ -25,8 +25,10 @@
  */
 
 struct net_generic {
-       unsigned int len;
-       struct rcu_head rcu;
+       struct {
+               unsigned int len;
+               struct rcu_head rcu;
+       } s;
 
        void *ptr[0];
 };

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 707b3c2..55e28a8 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -50,7 +50,7 @@ static struct net_generic *net_alloc_generic(void)
 
        ng = kzalloc(generic_size, GFP_KERNEL);
        if (ng)
-               ng->len = max_gen_ptrs;
+               ng->s.len = max_gen_ptrs;
 
        return ng;
 }
@@ -64,7 +64,7 @@ static int net_assign_generic(struct net *net, unsigned int id, void *data)
 
        old_ng = rcu_dereference_protected(net->gen,
                                           lockdep_is_held(&net_mutex));
-       if (old_ng->len >= id) {
+       if (old_ng->s.len >= id) {
                old_ng->ptr[id - 1] = data;
                return 0;
        }
@@ -84,11 +84,11 @@ static int net_assign_generic(struct net *net, unsigned int id, void *data)
         * the old copy for kfree after a grace period.
         */
 
-       memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
+       memcpy(&ng->ptr, &old_ng->ptr, old_ng->s.len * sizeof(void*));
        ng->ptr[id - 1] = data;
 
        rcu_assign_pointer(net->gen, ng);
-       kfree_rcu(old_ng, rcu);
+       kfree_rcu(old_ng, s.rcu);
        return 0;
 }