reparent_thread: don't call kill_orphaned_pgrp() if task_detached()

If task_detached(p) == T, then either

  a) p is not the main thread, we will find the group leader on the
     ->children list.

or

  b) p is the group leader but its ->exit_state = EXIT_DEAD.  This
     can only happen when the last sub-thread has died, but in that case
     that thread has already called kill_orphaned_pgrp() from
     exit_notify().

In both cases kill_orphaned_pgrp() looks bogus.

Move the task_detached() check up and simplify the code, this is also
right from the "common sense" pov: we should do nothing with the detached
childs, except move them to the new parent's ->children list.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 576eae233b53..405e6877168b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -818,6 +818,8 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father)
 
         list_move_tail(&p->sibling, &p->real_parent->children);
 
+        if (task_detached(p))
+                return;
         /* If this is a threaded reparent there is no need to
          * notify anyone anything has happened.
          */
@@ -825,15 +827,13 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father)
                 return;
 
         /* We don't want people slaying init.  */
-        if (!task_detached(p))
-                p->exit_signal = SIGCHLD;
+        p->exit_signal = SIGCHLD;
 
         /* If we'd notified the old parent about this child's death,
          * also notify the new parent.
          */
         if (!ptrace_reparented(p) &&
-            p->exit_state == EXIT_ZOMBIE &&
-            !task_detached(p) && thread_group_empty(p))
+            p->exit_state == EXIT_ZOMBIE && thread_group_empty(p))
                 do_notify_parent(p, p->exit_signal);
 
         kill_orphaned_pgrp(p, father);