[PATCH] fix non-leader exec under ptrace

This reverts most of commit 30e0fca6c1.
It broke the case of non-leader MT exec when ptraced.
I think the bug it was intended to fix was already addressed by commit
788e05a67c.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

kernel/ptrace.c

@@ -57,10 +57,6 @@ void ptrace_untrace(task_t *child)
 			signal_wake_up(child, 1);
 		}
 	}
-	if (child->signal->flags & SIGNAL_GROUP_EXIT) {
-		sigaddset(&child->pending.signal, SIGKILL);
-		signal_wake_up(child, 1);
-	}
 	spin_unlock(&child->sighand->siglock);
 }
 
@@ -82,7 +78,8 @@ void __ptrace_unlink(task_t *child)
 		SET_LINKS(child);
 	}
 
-	ptrace_untrace(child);
+	if (child->state == TASK_TRACED)
+		ptrace_untrace(child);
 }
 
 /*

kernel/signal.c

@@ -1942,9 +1942,9 @@ relock:
 			/* Let the debugger run.  */
 			ptrace_stop(signr, signr, info);
 
-			/* We're back.  Did the debugger cancel the sig or group_exit? */
+			/* We're back.  Did the debugger cancel the sig?  */
 			signr = current->exit_code;
-			if (signr == 0 || current->signal->flags & SIGNAL_GROUP_EXIT)
+			if (signr == 0)
 				continue;
 
 			current->exit_code = 0;