1 files changed, 27 insertions, 13 deletions

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index e981c61304f1..c8ef7c2992ed 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -26,19 +26,6 @@ static struct kmem_cache *nsproxy_cachep;
 
 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
-static inline void get_nsproxy(struct nsproxy *ns)
-{
-        atomic_inc(&ns->count);
-}
-
-void get_task_namespaces(struct task_struct *tsk)
-{
-        struct nsproxy *ns = tsk->nsproxy;
-        if (ns) {
-                get_nsproxy(ns);
-        }
-}
-
 /*
  * creates a copy of "orig" with refcount 1.
  */
@@ -216,6 +203,33 @@ out:
         return err;
 }
 
+void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
+{
+        struct nsproxy *ns;
+
+        might_sleep();
+
+        ns = p->nsproxy;
+
+        rcu_assign_pointer(p->nsproxy, new);
+
+        if (ns && atomic_dec_and_test(&ns->count)) {
+                /*
+                 * wait for others to get what they want from this nsproxy.
+                 *
+                 * cannot release this nsproxy via the call_rcu() since
+                 * put_mnt_ns() will want to sleep
+                 */
+                synchronize_rcu();
+                free_nsproxy(ns);
+        }
+}
+
+void exit_task_namespaces(struct task_struct *p)
+{
+        switch_task_namespaces(p, NULL);
+}
+
 static int __init nsproxy_cache_init(void)
 {
         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);