2 files changed, 20 insertions, 7 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index c7980810eb09..8d199033c0ca 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -89,9 +89,11 @@ extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type);
  * attach_pid() and detach_pid() must be called with the tasklist_lock
  * write-held.
  */
-extern int attach_pid(struct task_struct *task, enum pid_type type,
-                      struct pid *pid);
+extern void attach_pid(struct task_struct *task, enum pid_type type,
+                        struct pid *pid);
 extern void detach_pid(struct task_struct *task, enum pid_type);
+extern void change_pid(struct task_struct *task, enum pid_type,
+                        struct pid *pid);
 extern void transfer_pid(struct task_struct *old, struct task_struct *new,
                          enum pid_type);
 
diff --git a/kernel/pid.c b/kernel/pid.c
index e9a31d362b28..20d59fa2d493 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -317,7 +317,7 @@ EXPORT_SYMBOL_GPL(find_pid);
 /*
  * attach_pid() must be called with the tasklist_lock write-held.
  */
-int attach_pid(struct task_struct *task, enum pid_type type,
+void attach_pid(struct task_struct *task, enum pid_type type,
                 struct pid *pid)
 {
         struct pid_link *link;
@@ -325,11 +325,10 @@ int attach_pid(struct task_struct *task, enum pid_type type,
         link = &task->pids[type];
         link->pid = pid;
         hlist_add_head_rcu(&link->node, &pid->tasks[type]);
-
-        return 0;
 }
 
-void detach_pid(struct task_struct *task, enum pid_type type)
+static void __change_pid(struct task_struct *task, enum pid_type type,
+                        struct pid *new)
 {
         struct pid_link *link;
         struct pid *pid;
@@ -339,7 +338,7 @@ void detach_pid(struct task_struct *task, enum pid_type type)
         pid = link->pid;
 
         hlist_del_rcu(&link->node);
-        link->pid = NULL;
+        link->pid = new;
 
         for (tmp = PIDTYPE_MAX; --tmp >= 0; )
                 if (!hlist_empty(&pid->tasks[tmp]))
@@ -348,6 +347,18 @@ void detach_pid(struct task_struct *task, enum pid_type type)
         free_pid(pid);
 }
 
+void detach_pid(struct task_struct *task, enum pid_type type)
+{
+        __change_pid(task, type, NULL);
+}
+
+void change_pid(struct task_struct *task, enum pid_type type,
+                struct pid *pid)
+{
+        __change_pid(task, type, pid);
+        attach_pid(task, type, pid);
+}
+
 /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
 void transfer_pid(struct task_struct *old, struct task_struct *new,
                            enum pid_type type)