[PATCH net-next 2/5] net: Reflect all pernet_operations are converted

[Kirill Tkhai]

All pernet_operations are reviewed and converted, hooray!
Reflect this in core code: setup_net() and cleanup_net()
will take down_read() always.

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 net/core/net_namespace.c |   43 ++++++-------------------------------------
 1 file changed, 6 insertions(+), 37 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 95ba2c53bd9a..0f614523a13f 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -40,9 +40,8 @@ struct net init_net = {
 EXPORT_SYMBOL(init_net);
 
 static bool init_net_initialized;
-static unsigned nr_sync_pernet_ops;
 /*
- * net_sem: protects: pernet_list, net_generic_ids, nr_sync_pernet_ops,
+ * net_sem: protects: pernet_list, net_generic_ids,
  * init_net_initialized and first_device pointer.
  */
 DECLARE_RWSEM(net_sem);
@@ -406,7 +405,6 @@ struct net *copy_net_ns(unsigned long flags,
 {
        struct ucounts *ucounts;
        struct net *net;
-       unsigned write;
        int rv;
 
        if (!(flags & CLONE_NEWNET))
@@ -424,25 +422,14 @@ struct net *copy_net_ns(unsigned long flags,
        refcount_set(&net->passive, 1);
        net->ucounts = ucounts;
        get_user_ns(user_ns);
-again:
-       write = READ_ONCE(nr_sync_pernet_ops);
-       if (write)
-               rv = down_write_killable(&net_sem);
-       else
-               rv = down_read_killable(&net_sem);
+
+       rv = down_read_killable(&net_sem);
        if (rv < 0)
                goto put_userns;
 
-       if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) {
-               up_read(&net_sem);
-               goto again;
-       }
        rv = setup_net(net, user_ns);
 
-       if (write)
-               up_write(&net_sem);
-       else
-               up_read(&net_sem);
+       up_read(&net_sem);
 
        if (rv < 0) {
 put_userns:
@@ -490,21 +477,11 @@ static void cleanup_net(struct work_struct *work)
        struct net *net, *tmp, *last;
        struct llist_node *net_kill_list;
        LIST_HEAD(net_exit_list);
-       unsigned write;
 
        /* Atomically snapshot the list of namespaces to cleanup */
        net_kill_list = llist_del_all(&cleanup_list);
-again:
-       write = READ_ONCE(nr_sync_pernet_ops);
-       if (write)
-               down_write(&net_sem);
-       else
-               down_read(&net_sem);
 
-       if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) {
-               up_read(&net_sem);
-               goto again;
-       }
+       down_read(&net_sem);
 
        /* Don't let anyone else find us. */
        rtnl_lock();
@@ -543,10 +520,7 @@ static void cleanup_net(struct work_struct *work)
        list_for_each_entry_reverse(ops, &pernet_list, list)
                ops_free_list(ops, &net_exit_list);
 
-       if (write)
-               up_write(&net_sem);
-       else
-               up_read(&net_sem);
+       up_read(&net_sem);
 
        /* Ensure there are no outstanding rcu callbacks using this
         * network namespace.
@@ -1006,9 +980,6 @@ static int register_pernet_operations(struct list_head 
*list,
                rcu_barrier();
                if (ops->id)
                        ida_remove(&net_generic_ids, *ops->id);
-       } else if (!ops->async) {
-               pr_info_once("Pernet operations %ps are sync.\n", ops);
-               nr_sync_pernet_ops++;
        }
 
        return error;
@@ -1016,8 +987,6 @@ static int register_pernet_operations(struct list_head 
*list,
 
 static void unregister_pernet_operations(struct pernet_operations *ops)
 {
-       if (!ops->async)
-               BUG_ON(nr_sync_pernet_ops-- == 0);
        __unregister_pernet_operations(ops);
        rcu_barrier();
        if (ops->id)