net: Add support for batching network namespace cleanups

- Add exit_list to struct net to support building lists of network
  namespaces to cleanup.

- Add exit_batch to pernet_operations to allow running operations only
  once during a network namespace exit.  Instead of once per network
  namespace.

- Factor opt ops_exit_list and ops_exit_free so the logic with cleanup
  up a network namespace does not need to be duplicated.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 24a8c5591f63..f307e133d14c 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -43,6 +43,7 @@ struct net {
 #endif
         struct list_head        list;           /* list of network namespaces */
         struct list_head        cleanup_list;   /* namespaces on death row */
+        struct list_head        exit_list;      /* Use only net_mutex */
 
         struct proc_dir_entry   *proc_net;
         struct proc_dir_entry   *proc_net_stat;
@@ -236,6 +237,7 @@ struct pernet_operations {
         struct list_head list;
         int (*init)(struct net *net);
         void (*exit)(struct net *net);
+        void (*exit_batch)(struct list_head *net_exit_list);
         int *id;
         size_t size;
 };