[PATCH] utrace_wakeup: take ->group_stop_count into account

[Oleg Nesterov]

utrace_wakeup() should take ->group_stop_count into account,
we should not wake up if group stop is in progress.

Also, kill "sighand" variable.

Signed-off-by: Oleg Nesterov <o...@redhat.com>

--- __UTRACE/kernel/utrace.c~WAKEUP_CHECK_GSC   2009-07-28 20:56:32.000000000 
+0200
+++ __UTRACE/kernel/utrace.c    2009-07-28 21:55:43.000000000 +0200
@@ -807,17 +807,16 @@ static bool utrace_do_stop(struct task_s
  */
 static void utrace_wakeup(struct task_struct *target, struct utrace *utrace)
 {
-       struct sighand_struct *sighand;
        unsigned long irqflags;
 
        utrace->stopped = 0;
 
-       sighand = lock_task_sighand(target, &irqflags);
-       if (unlikely(!sighand))
+       if (!lock_task_sighand(target, &irqflags))
                return;
 
        if (likely(task_is_stopped_or_traced(target))) {
-               if (target->signal->flags & SIGNAL_STOP_STOPPED)
+               if (target->signal->flags & SIGNAL_STOP_STOPPED ||
+                   target->signal->group_stop_count)
                        target->state = TASK_STOPPED;
                else
                        wake_up_state(target, __TASK_STOPPED | __TASK_TRACED);