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 6642DC00A89 for ; Mon, 2 Nov 2020 22:30:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 073B12225B for ; Mon, 2 Nov 2020 22:30:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726504AbgKBWav convert rfc822-to-8bit (ORCPT ); Mon, 2 Nov 2020 17:30:51 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:42979 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725785AbgKBWau (ORCPT ); Mon, 2 Nov 2020 17:30:50 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mtapsc-3-j6bXPPu-Nl6LRhxQXu1CQQ-1; Mon, 02 Nov 2020 22:30:46 +0000 X-MC-Unique: j6bXPPu-Nl6LRhxQXu1CQQ-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; Mon, 2 Nov 2020 22:30:45 +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; Mon, 2 Nov 2020 22:30:45 +0000 From: David Laight To: 'Greg KH' , Alex Deucher CC: Deepak R Varma , Alex Deucher , =?iso-8859-1?Q?Christian_K=F6nig?= , David Airlie , Daniel Vetter , amd-gfx list , "Maling list - DRI developers" , LKML , Melissa Wen , "Daniel Vetter" Subject: RE: [PATCH] drm/amdgpu: do not initialise global variables to 0 or NULL Thread-Topic: [PATCH] drm/amdgpu: do not initialise global variables to 0 or NULL Thread-Index: AQHWsVQzuHsYTLqYC0GrzZhKR8oU56m1aalA Date: Mon, 2 Nov 2020 22:30:45 +0000 Message-ID: References: <20201102184147.GA42288@localhost> <20201102201040.GA2433494@kroah.com> In-Reply-To: <20201102201040.GA2433494@kroah.com> 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: linux-kernel@vger.kernel.org From: Greg KH > Sent: 02 November 2020 20:11 > > On Mon, Nov 02, 2020 at 02:43:45PM -0500, Alex Deucher wrote: > > On Mon, Nov 2, 2020 at 1:42 PM Deepak R Varma wrote: > > > > > > Initializing global variable to 0 or NULL is not necessary and should > > > be avoided. Issue reported by checkpatch script as: > > > ERROR: do not initialise globals to 0 (or NULL). > > > > I agree that this is technically correct, but a lot of people don't > > seem to know that so we get a lot of comments about this code for the > > variables that are not explicitly set. Seems less confusing to > > initialize them even if it not necessary. I don't have a particularly > > strong opinion on it however. > > The kernel coding style is to do it this way. You even save space and > time by doing it as well :) Uninitialised globals end up as 'named common' (variables that are their own code section - from FORTRAN) until the final link puts them into the .bss. Globals initialised to 0 go into the .bss of the object file being created. So both end up in the final .bss. If the code goes into a module you aren't allowed 'common' data in a module to every global must be initialised. I'm surprised checkpatch complains. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)