[PATCH] restore ->pdeath_signal behaviour

Commit b2b2cbc4 introduced a user-
visible change: ->pdeath_signal is sent only when the entire thread
group exits.

While this change is imho good, it may break things.  So restore the
old behaviour for now.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
To: Albert Cahalan <acahalan@gmail.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Linus Torvalds <torvalds@osdl.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Qi Yong <qiyong@fc-cn.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/exit.c

@@ -597,6 +597,10 @@ choose_new_parent(struct task_struct *p, struct task_struct *reaper)
 static void
 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 {
+	if (p->pdeath_signal)
+		/* We already hold the tasklist_lock here.  */
+		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
+
 	/* Move the child from its dying parent to the new one.  */
 	if (unlikely(traced)) {
 		/* Preserve ptrace links if someone else is tracing this child.  */
@@ -632,10 +636,6 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 	if (p->exit_signal != -1)
 		p->exit_signal = SIGCHLD;
 
-	if (p->pdeath_signal)
-		/* We already hold the tasklist_lock here.  */
-		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
-
 	/* If we'd notified the old parent about this child's death,
 	 * also notify the new parent.
 	 */