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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 DCB9FC169C4 for ; Sun, 3 Feb 2019 19:05:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABB4C217D6 for ; Sun, 3 Feb 2019 19:05:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727192AbfBCTEg (ORCPT ); Sun, 3 Feb 2019 14:04:36 -0500 Received: from proxy01.fsdata.se ([89.221.252.211]:25473 "EHLO mail-gw01.fsdata.se" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726737AbfBCTEg (ORCPT ); Sun, 3 Feb 2019 14:04:36 -0500 Received: from localhost (94.234.42.90) by DAG01.HMC.local (192.168.46.11) with Microsoft SMTP Server (TLS) id 15.0.1263.5; Sun, 3 Feb 2019 20:04:28 +0100 Date: Sun, 3 Feb 2019 20:04:23 +0100 From: Mattias Jacobsson <2pi@mok.nu> To: Andy Shevchenko CC: Masahiro Yamada , , Darren Hart , "Andy Shevchenko" , Pali =?utf-8?B?Um9ow6Fy?= , Platform Driver , Linux Kernel Mailing List , <2pi@mok.nu> Subject: Re: [PATCH v3 2/3] platform/x86: wmi: add WMI support to MODULE_DEVICE_TABLE() Message-ID: <20190203190423.lmsix5la6ioyawwi@mok.nu> References: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Originating-IP: [94.234.42.90] X-ClientProxiedBy: PROXY03.HMC.local (192.168.46.53) To DAG01.HMC.local (192.168.46.11) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-01-30, Andy Shevchenko wrote: > On Wed, Jan 30, 2019 at 5:15 PM Mattias Jacobsson <2pi@mok.nu> wrote: > > > > The kernel provides the macro MODULE_DEVICE_TABLE() where driver authors > > can specify their device type and their array of device_ids and thereby > > trigger the generation of the appropriate MODULE_ALIAS() output. This is > > opposed to having to specify one MODULE_ALIAS() for each device. The WMI > > device type is currently not supported. > > > > While using MODULE_DEVICE_TABLE() does increase the complexity as well > > as spreading out the implementation across the kernel, it does come with > > some benefits too; > > * It makes different drivers look more similar; if you can specify the > > array of device_ids any device type specific input to MODULE_ALIAS() > > will automatically be generated for you. > > * It helps each driver avoid keeping multiple versions of the same > > information in sync. That is, both the array of device_ids and the > > potential multitude of MODULE_ALIAS()'s. > > > > Add WMI support to MODULE_DEVICE_TABLE() by adding info about struct > > wmi_device_id in devicetable-offsets.c and add a WMI entry point in > > file2alias.c. > > > > The type argument for MODULE_DEVICE_TABLE(type, name) is wmi. > > > > Suggested-by: Pali Rohár > > Signed-off-by: Mattias Jacobsson <2pi@mok.nu> > > --- > > > > What do you think about this usage of snprintf()? Now we check if there > > is an error or if the printed string tried to exceeded the buffer. > > Ideally 500 should be a macro or a parameter, but there isn't one > > available. The number 500 comes from a few lines below in the function > > do_table(). > > This looks better, though minor comments. > > Indeed, 500 would be nicer to be defined as a constant (via preprocessor macro). > > > +/* Looks like: wmi:guid */ > > +static int do_wmi_entry(const char *filename, void *symval, char *alias) > > +{ > > + DEF_FIELD_ADDR(symval, wmi_device_id, guid_string); > > + if (strlen(*guid_string) != UUID_STRING_LEN) { > > + warn("Invalid WMI device id 'wmi:%s' in '%s'\n", > > + *guid_string, filename); > > + return 0; > > + } > > + > > > + int len = snprintf(alias, 500, WMI_MODULE_PREFIX "%s", *guid_string); > > Please, split declaration and assignment... Done. > > > + > > ...and drop this line. Done. > > > + if (len < 0 || len >= 500) { > > Would it even possible to get a negative number here? > Same for any other number than slightly bigger than 36. snprintf returns a negative number on error. BTW AFAIU the code from file2alias.c gets dynamically linked against a libc. > > You have above a check and here is the matter of either sudden > replacement of the string during the operation or how snprintf is > broken itself. > Do you have a case in mind which can bring to the above conditions? > > > + warn("Could not generate all MODULE_ALIAS's in '%s'\n", > > + filename); > > + return 0; > > + } > > On top of that you have an ordinary case here and in similar ones we > don't care about buffer size at all (perhaps BUILD_BUG_ON() what is > needed here). I used warn() as it is what is being used in similar conditions elsewhere in the file. > > So, what about simple > > { > DEF_FIELD_ADDR(...); > size_t len; > > len = strlen(*guid_string); > if (len != ...) { > ... > } > sprintf(...); > return 1; > } > > ? Then we are missing the check that we are within the bounds of alias as well as the negative code from s*printf(). snprintf() does this nicely for us. > > > + return 1; > > +} > > + > > /* Does namelen bytes of name exactly match the symbol? */ > > static bool sym_is(const char *name, unsigned namelen, const char *symbol) > > { > > @@ -1357,6 +1378,7 @@ static const struct devtable devtable[] = { > > {"fslmc", SIZE_fsl_mc_device_id, do_fsl_mc_entry}, > > {"tbsvc", SIZE_tb_service_id, do_tbsvc_entry}, > > {"typec", SIZE_typec_device_id, do_typec_entry}, > > + {"wmi", SIZE_wmi_device_id, do_wmi_entry}, > > }; > > > > /* Create MODULE_ALIAS() statements. > > -- > > 2.20.1 > > > > > -- > With Best Regards, > Andy Shevchenko Thanks, Mattias