[PATCH] Call exit_itimers from do_exit, not __exit_signal

When I originally moved exit_itimers into __exit_signal, that was the only
place where we could reliably know it was the last thread in the group
dying, without races.  Since then we've gotten the signal_struct.live
counter, and do_exit can reliably do group-wide cleanup work.

This patch moves the call to do_exit, where it's made without locks.  This
avoids the deadlock issues that the old __exit_signal code's comment talks
about, and the one that Oleg found recently with process CPU timers.

[ This replaces e03d13e985d48ac4885382c9e3b1510c78bd047f, which is why
  it was just reverted. ]

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index 4307773..3b25b18 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -843,6 +843,7 @@
 	group_dead = atomic_dec_and_test(&tsk->signal->live);
 	if (group_dead) {
  		del_timer_sync(&tsk->signal->real_timer);
+		exit_itimers(tsk->signal);
 		acct_process(code);
 	}
 	exit_mm(tsk);