4 files changed, 30 insertions, 28 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 562a175c35a9..c7d1e4689325 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -36,7 +36,7 @@ extern int rtnl_is_locked(void);
 extern int rtnl_lock_killable(void);
 
 extern wait_queue_head_t netdev_unregistering_wq;
-extern struct rw_semaphore net_sem;
+extern struct rw_semaphore pernet_ops_rwsem;
 
 #ifdef CONFIG_PROVE_LOCKING
 extern bool lockdep_rtnl_is_held(void);
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 37bcf8382b61..922e8b6fb422 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -60,9 +60,10 @@ struct net {
 
         struct list_head        list;           /* list of network namespaces */
         struct list_head        exit_list;      /* To linked to call pernet exit
-                                                 * methods on dead net (net_sem
-                                                 * read locked), or to unregister
-                                                 * pernet ops (net_sem wr locked).
+                                                 * methods on dead net (
+                                                 * pernet_ops_rwsem read locked),
+                                                 * or to unregister pernet ops
+                                                 * (pernet_ops_rwsem write locked).
                                                  */
         struct llist_node       cleanup_list;   /* namespaces on death row */
 
@@ -95,8 +96,9 @@ struct net {
         /* core fib_rules */
         struct list_head        rules_ops;
 
-        struct list_head        fib_notifier_ops;  /* protected by net_sem */
-
+        struct list_head        fib_notifier_ops;  /* Populated by
+                                                    * register_pernet_subsys()
+                                                    */
         struct net_device       *loopback_dev;          /* The loopback */
         struct netns_core       core;
         struct netns_mib        mib;
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index eef17ad29dea..9e8ee4640451 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -41,10 +41,10 @@ EXPORT_SYMBOL(init_net);
 
 static bool init_net_initialized;
 /*
- * net_sem: protects: pernet_list, net_generic_ids,
+ * pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
  * init_net_initialized and first_device pointer.
  */
-DECLARE_RWSEM(net_sem);
+DECLARE_RWSEM(pernet_ops_rwsem);
 
 #define MIN_PERNET_OPS_ID       \
         ((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))
@@ -72,7 +72,7 @@ static int net_assign_generic(struct net *net, unsigned int id, void *data)
         BUG_ON(id < MIN_PERNET_OPS_ID);
 
         old_ng = rcu_dereference_protected(net->gen,
-                                           lockdep_is_held(&net_sem));
+                                           lockdep_is_held(&pernet_ops_rwsem));
         if (old_ng->s.len > id) {
                 old_ng->ptr[id] = data;
                 return 0;
@@ -289,7 +289,7 @@ struct net *get_net_ns_by_id(struct net *net, int id)
  */
 static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
 {
-        /* Must be called with net_sem held */
+        /* Must be called with pernet_ops_rwsem held */
         const struct pernet_operations *ops, *saved_ops;
         int error = 0;
         LIST_HEAD(net_exit_list);
@@ -422,13 +422,13 @@ struct net *copy_net_ns(unsigned long flags,
         net->ucounts = ucounts;
         get_user_ns(user_ns);
 
-        rv = down_read_killable(&net_sem);
+        rv = down_read_killable(&pernet_ops_rwsem);
         if (rv < 0)
                 goto put_userns;
 
         rv = setup_net(net, user_ns);
 
-        up_read(&net_sem);
+        up_read(&pernet_ops_rwsem);
 
         if (rv < 0) {
 put_userns:
@@ -480,7 +480,7 @@ static void cleanup_net(struct work_struct *work)
         /* Atomically snapshot the list of namespaces to cleanup */
         net_kill_list = llist_del_all(&cleanup_list);
 
-        down_read(&net_sem);
+        down_read(&pernet_ops_rwsem);
 
         /* Don't let anyone else find us. */
         rtnl_lock();
@@ -519,7 +519,7 @@ static void cleanup_net(struct work_struct *work)
         list_for_each_entry_reverse(ops, &pernet_list, list)
                 ops_free_list(ops, &net_exit_list);
 
-        up_read(&net_sem);
+        up_read(&pernet_ops_rwsem);
 
         /* Ensure there are no outstanding rcu callbacks using this
          * network namespace.
@@ -546,8 +546,8 @@ static void cleanup_net(struct work_struct *work)
  */
 void net_ns_barrier(void)
 {
-        down_write(&net_sem);
-        up_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
+        up_write(&pernet_ops_rwsem);
 }
 EXPORT_SYMBOL(net_ns_barrier);
 
@@ -869,12 +869,12 @@ static int __init net_ns_init(void)
 
         rcu_assign_pointer(init_net.gen, ng);
 
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         if (setup_net(&init_net, &init_user_ns))
                 panic("Could not setup the initial network namespace");
 
         init_net_initialized = true;
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
 
         register_pernet_subsys(&net_ns_ops);
 
@@ -1013,9 +1013,9 @@ static void unregister_pernet_operations(struct pernet_operations *ops)
 int register_pernet_subsys(struct pernet_operations *ops)
 {
         int error;
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         error =  register_pernet_operations(first_device, ops);
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
         return error;
 }
 EXPORT_SYMBOL_GPL(register_pernet_subsys);
@@ -1031,9 +1031,9 @@ EXPORT_SYMBOL_GPL(register_pernet_subsys);
  */
 void unregister_pernet_subsys(struct pernet_operations *ops)
 {
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         unregister_pernet_operations(ops);
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
 }
 EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
 
@@ -1059,11 +1059,11 @@ EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
 int register_pernet_device(struct pernet_operations *ops)
 {
         int error;
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         error = register_pernet_operations(&pernet_list, ops);
         if (!error && (first_device == &pernet_list))
                 first_device = &ops->list;
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
         return error;
 }
 EXPORT_SYMBOL_GPL(register_pernet_device);
@@ -1079,11 +1079,11 @@ EXPORT_SYMBOL_GPL(register_pernet_device);
  */
 void unregister_pernet_device(struct pernet_operations *ops)
 {
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         if (&ops->list == first_device)
                 first_device = first_device->next;
         unregister_pernet_operations(ops);
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
 }
 EXPORT_SYMBOL_GPL(unregister_pernet_device);
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 31438b63d4b4..73011a60434c 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -460,11 +460,11 @@ static void rtnl_lock_unregistering_all(void)
 void rtnl_link_unregister(struct rtnl_link_ops *ops)
 {
         /* Close the race with cleanup_net() */
-        down_write(&net_sem);
+        down_write(&pernet_ops_rwsem);
         rtnl_lock_unregistering_all();
         __rtnl_link_unregister(ops);
         rtnl_unlock();
-        up_write(&net_sem);
+        up_write(&pernet_ops_rwsem);
 }
 EXPORT_SYMBOL_GPL(rtnl_link_unregister);