From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DED9C433E0 for ; Fri, 29 Jan 2021 05:11:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CE1E64E02 for ; Fri, 29 Jan 2021 05:11:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231826AbhA2FLA (ORCPT ); Fri, 29 Jan 2021 00:11:00 -0500 Received: from verein.lst.de ([213.95.11.211]:59972 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231287AbhA2FK7 (ORCPT ); Fri, 29 Jan 2021 00:10:59 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 9FA1568AFE; Fri, 29 Jan 2021 06:10:12 +0100 (CET) Date: Fri, 29 Jan 2021 06:10:12 +0100 From: Christoph Hellwig To: Thiago Jung Bauermann Cc: Christoph Hellwig , Frederic Barrat , Andrew Donnellan , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Jessica Yu , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Michal Marek , linux-kbuild@vger.kernel.org, Masahiro Yamada , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 04/13] module: use RCU to synchronize find_module Message-ID: <20210129051012.GA2053@lst.de> References: <20210128181421.2279-1-hch@lst.de> <20210128181421.2279-5-hch@lst.de> <874kj023bj.fsf@manicouagan.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874kj023bj.fsf@manicouagan.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 28, 2021 at 05:50:56PM -0300, Thiago Jung Bauermann wrote: > > struct module *find_module(const char *name) > > { > > - module_assert_mutex(); > > Does it make sense to replace the assert above with the warn below (untested)? > > RCU_LOCKDEP_WARN(rcu_read_lock_sched_held()); One caller actually holds module_mutex still. And find_module_all, which implements the actual logic already asserts that either module_mutex is held or rcu_read_lock, so I don't tink we need an extra one here. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC24EC433DB for ; Fri, 29 Jan 2021 05:12:21 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B060C64DFD for ; Fri, 29 Jan 2021 05:12:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B060C64DFD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4DRlns1WZDzDrg2 for ; Fri, 29 Jan 2021 16:12:17 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4DRlll0XmDzDrfS for ; Fri, 29 Jan 2021 16:10:20 +1100 (AEDT) Received: by verein.lst.de (Postfix, from userid 2407) id 9FA1568AFE; Fri, 29 Jan 2021 06:10:12 +0100 (CET) Date: Fri, 29 Jan 2021 06:10:12 +0100 From: Christoph Hellwig To: Thiago Jung Bauermann Subject: Re: [PATCH 04/13] module: use RCU to synchronize find_module Message-ID: <20210129051012.GA2053@lst.de> References: <20210128181421.2279-1-hch@lst.de> <20210128181421.2279-5-hch@lst.de> <874kj023bj.fsf@manicouagan.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874kj023bj.fsf@manicouagan.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Petr Mladek , Jiri Kosina , Andrew Donnellan , linux-kbuild@vger.kernel.org, David Airlie , Masahiro Yamada , Josh Poimboeuf , Maarten Lankhorst , linux-kernel@vger.kernel.org, Maxime Ripard , live-patching@vger.kernel.org, Michal Marek , Joe Lawrence , dri-devel@lists.freedesktop.org, Thomas Zimmermann , Jessica Yu , Frederic Barrat , Daniel Vetter , Miroslav Benes , linuxppc-dev@lists.ozlabs.org, Christoph Hellwig Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jan 28, 2021 at 05:50:56PM -0300, Thiago Jung Bauermann wrote: > > struct module *find_module(const char *name) > > { > > - module_assert_mutex(); > > Does it make sense to replace the assert above with the warn below (untested)? > > RCU_LOCKDEP_WARN(rcu_read_lock_sched_held()); One caller actually holds module_mutex still. And find_module_all, which implements the actual logic already asserts that either module_mutex is held or rcu_read_lock, so I don't tink we need an extra one here.