2 files changed, 16 insertions, 11 deletions

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index b1875582c1a1..12532839f508 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -493,16 +493,21 @@ static inline int tracehook_notify_jctl(int notify, int why)
  * @death_cookie:       value to pass to tracehook_report_death()
  * @group_dead:         nonzero if this was the last thread in the group to die
  *
- * Return the signal number to send our parent with do_notify_parent(), or
- * zero to send no signal and leave a zombie, or -1 to self-reap right now.
+ * A return value >= 0 means call do_notify_parent() with that signal
+ * number.  Negative return value can be %DEATH_REAP to self-reap right
+ * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our
+ * parent.  Note that a return value of 0 means a do_notify_parent() call
+ * that sends no signal, but still wakes up a parent blocked in wait*().
  *
  * Called with write_lock_irq(&tasklist_lock) held.
  */
+#define DEATH_REAP                      -1
+#define DEATH_DELAYED_GROUP_LEADER      -2
 static inline int tracehook_notify_death(struct task_struct *task,
                                          void **death_cookie, int group_dead)
 {
         if (task->exit_signal == -1)
-                return task->ptrace ? SIGCHLD : -1;
+                return task->ptrace ? SIGCHLD : DEATH_REAP;
 
         /*
          * If something other than our normal parent is ptracing us, then
@@ -512,21 +517,21 @@ static inline int tracehook_notify_death(struct task_struct *task,
         if (thread_group_empty(task) && !ptrace_reparented(task))
                 return task->exit_signal;
 
-        return task->ptrace ? SIGCHLD : 0;
+        return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER;
 }
 
 /**
  * tracehook_report_death - task is dead and ready to be reaped
  * @task:               @current task now exiting
- * @signal:             signal number sent to parent, or 0 or -1
+ * @signal:             return value from tracheook_notify_death()
  * @death_cookie:       value passed back from tracehook_notify_death()
  * @group_dead:         nonzero if this was the last thread in the group to die
  *
  * Thread has just become a zombie or is about to self-reap.  If positive,
  * @signal is the signal number just sent to the parent (usually %SIGCHLD).
- * If @signal is -1, this thread will self-reap.  If @signal is 0, this is
- * a delayed_group_leader() zombie.  The @death_cookie was passed back by
- * tracehook_notify_death().
+ * If @signal is %DEATH_REAP, this thread will self-reap.  If @signal is
+ * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie.
+ * The @death_cookie was passed back by tracehook_notify_death().
  *
  * If normal reaping is not inhibited, @task->exit_state might be changing
  * in parallel.
diff --git a/kernel/exit.c b/kernel/exit.c
index eb4d6470d1d0..38ec40630149 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -911,10 +911,10 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
                 tsk->exit_signal = SIGCHLD;
 
         signal = tracehook_notify_death(tsk, &cookie, group_dead);
-        if (signal > 0)
+        if (signal >= 0)
                 signal = do_notify_parent(tsk, signal);
 
-        tsk->exit_state = signal < 0 ? EXIT_DEAD : EXIT_ZOMBIE;
+        tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
 
         /* mt-exec, de_thread() is waiting for us */
         if (thread_group_leader(tsk) &&
@@ -927,7 +927,7 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
         tracehook_report_death(tsk, signal, cookie, group_dead);
 
         /* If the process is dead, release it - nobody will wait for it */
-        if (signal < 0)
+        if (signal == DEATH_REAP)
                 release_task(tsk);
 }