From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751692Ab0CRSzV (ORCPT ); Thu, 18 Mar 2010 14:55:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9188 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751410Ab0CRSzP (ORCPT ); Thu, 18 Mar 2010 14:55:15 -0400 Date: Thu, 18 Mar 2010 19:53:07 +0100 From: Oleg Nesterov To: Andrew Morton Cc: Fenghua Yu , Roland McGrath , Stanislaw Gruszka , Tony Luck , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] ia64: ptrace_attach_sync_user_rbs: avoid "task->signal != NULL" checks Message-ID: <20100318185307.GA18352@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 No functional changes. It doesn't matter which pointer we check under tasklist to ensure the task was not released, ->signal or ->sighand. But we are going to make ->signal refcountable, change the code to use ->sighand. Note: this code doesn't need this check and tasklist_lock at all, it should be converted to use lock_task_sighand(). And, the code under SIGNAL_STOP_STOPPED check looks wrong. Signed-off-by: Oleg Nesterov --- arch/ia64/kernel/ptrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- 34-rc1/arch/ia64/kernel/ptrace.c~6_IA64_DONT_CHECK_SIGNAL 2010-03-11 13:11:48.000000000 +0100 +++ 34-rc1/arch/ia64/kernel/ptrace.c 2010-03-18 19:12:45.000000000 +0100 @@ -639,7 +639,7 @@ ptrace_attach_sync_user_rbs (struct task */ read_lock(&tasklist_lock); - if (child->signal) { + if (child->sighand) { spin_lock_irq(&child->sighand->siglock); if (child->state == TASK_STOPPED && !test_and_set_tsk_thread_flag(child, TIF_RESTORE_RSE)) { @@ -663,7 +663,7 @@ ptrace_attach_sync_user_rbs (struct task * job control stop, so that SIGCONT can be used to wake it up. */ read_lock(&tasklist_lock); - if (child->signal) { + if (child->sighand) { spin_lock_irq(&child->sighand->siglock); if (child->state == TASK_TRACED && (child->signal->flags & SIGNAL_STOP_STOPPED)) {