From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1749667AbXDIJwE (ORCPT ); Mon, 9 Apr 2007 05:52:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750827AbXDIJwE (ORCPT ); Mon, 9 Apr 2007 05:52:04 -0400 Received: from mailhub.sw.ru ([195.214.233.200]:25399 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1749667AbXDIJwD (ORCPT ); Mon, 9 Apr 2007 05:52:03 -0400 Message-ID: <461A0DDC.5060709@sw.ru> Date: Mon, 09 Apr 2007 13:56:44 +0400 From: Pavel Emelianov User-Agent: Thunderbird 1.5 (X11/20060317) MIME-Version: 1.0 To: Andrew Morton CC: Ingo Molnar , Arjan van de Ven , Linux Kernel Mailing List Subject: [PATCH] Lockdep treats down_write_trylock like regular down_write Content-Type: multipart/mixed; boundary="------------080507010603020204060803" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------080507010603020204060803 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit This causes constructions like down_write(&mm1->mmap_sem); if (down_write_trylock(&mm2->mmap_sem)) { ... up_write(&mm2->mmap_sem); } up_write(&mm1->mmap_sem); generate a lockdep warning about circular locking dependence. Call rwsem_acquire() with trylock set to 1. --------------080507010603020204060803 Content-Type: text/plain; name="diff-lockdep-rwsem-trylock" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="diff-lockdep-rwsem-trylock" --- ./kernel/rwsem.c.pbonrem 2007-03-06 19:09:50.000000000 +0300 +++ ./kernel/rwsem.c 2007-04-06 14:02:18.000000000 +0400 @@ -60,7 +60,7 @@ int down_write_trylock(struct rw_semapho int ret = __down_write_trylock(sem); if (ret == 1) - rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); + rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_); return ret; } --------------080507010603020204060803--