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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3D923C433DB for ; Thu, 21 Jan 2021 17:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2D8021973 for ; Thu, 21 Jan 2021 17:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388646AbhAURxb convert rfc822-to-8bit (ORCPT ); Thu, 21 Jan 2021 12:53:31 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:46904 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389071AbhAURqq (ORCPT ); Thu, 21 Jan 2021 12:46:46 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-7-70jJZbebO02FvmwaO8iuwQ-1; Thu, 21 Jan 2021 17:44:57 +0000 X-MC-Unique: 70jJZbebO02FvmwaO8iuwQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Thu, 21 Jan 2021 17:44:55 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Thu, 21 Jan 2021 17:44:55 +0000 From: David Laight To: 'Christoph Hellwig' , Christophe Leroy 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" Subject: RE: [PATCH 02/13] module: add a module_loaded helper Thread-Topic: [PATCH 02/13] module: add a module_loaded helper Thread-Index: AQHW8BhvE0+Qt/OaHkK/jwqI2nu4BKoyViXg Date: Thu, 21 Jan 2021 17:44:55 +0000 Message-ID: <8d59f11971764db2a104c87937e1d3ab@AcuMS.aculab.com> References: <20210121074959.313333-1-hch@lst.de> <20210121074959.313333-3-hch@lst.de> <844a7fc3-2cba-46d2-fd4e-e5fe16b08573@csgroup.eu> <20210121171119.GA29916@lst.de> In-Reply-To: <20210121171119.GA29916@lst.de> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org > > On Thu, Jan 21, 2021 at 11:00:20AM +0100, Christophe Leroy wrote: > > > +bool module_loaded(const char *name); > > > > Maybe module_is_loaded() would be a better name. > > Fine with me. It does look like both callers aren't 'unsafe'. But it is a bit strange returning a stale value. It did make be look a bit more deeply at try_module_get(). For THIS_MODULE (eg to get an extra reference for a kthread) I doubt it can ever fail. But the other cases require a 'module' structure be passed in. ISTM that unloading the module could invalidate the pointer that has just been read from some other structure. I'm guessing that some other lock must always be held. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)