From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753312AbZBHSu7 (ORCPT ); Sun, 8 Feb 2009 13:50:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753514AbZBHSt6 (ORCPT ); Sun, 8 Feb 2009 13:49:58 -0500 Received: from mx2.redhat.com ([66.187.237.31]:36121 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753470AbZBHSt5 (ORCPT ); Sun, 8 Feb 2009 13:49:57 -0500 Date: Sun, 8 Feb 2009 19:47:30 +0100 From: Oleg Nesterov To: Andrew Morton Cc: Jerome Marchand , Roland McGrath , Denys Vlasenko , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] ptrace_untrace: fix the SIGNAL_STOP_STOPPED check Message-ID: <20090208184730.GA27086@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This bug is ancient too. ptrace_untrace() must not resume the task if the group stop in progress, we should set TASK_STOPPED instead. Unfortunately, we still have problems here: - if the process/thread was traced, SIGNAL_STOP_STOPPED does not necessary means this thread group is stopped. - ptrace breaks the bookkeeping of ->group_stop_count. (the comment above ptrace_untrace() doesn't look exactly right too). Signed-off-by: Oleg Nesterov --- 6.29-rc3/kernel/ptrace.c~3_FIX_STOPPED 2009-02-08 06:22:26.000000000 +0100 +++ 6.29-rc3/kernel/ptrace.c 2009-02-08 08:52:14.000000000 +0100 @@ -60,7 +60,8 @@ static void ptrace_untrace(struct task_s { spin_lock(&child->sighand->siglock); if (task_is_traced(child)) { - if (child->signal->flags & SIGNAL_STOP_STOPPED) + if (child->signal->flags & SIGNAL_STOP_STOPPED || + child->signal->group_stop_count) __set_task_state(child, TASK_STOPPED); else wake_up_process(child);