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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 4A2A5C34047 for ; Wed, 19 Feb 2020 12:19:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 152AB24654 for ; Wed, 19 Feb 2020 12:19:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582114763; bh=TRqdYvf0Y/OocZGiHSaC6g7JfORCgxGpXUneLxerl7I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=oeGtMDwuvOc6yIRCsfpssQq7NNeexIsNbwgqRY24RUX/1pAy3Gxn6em8IWcKyz604 iDA7k0wcqVl8ATo5Hf14IhfLQl0axx7FAd9m4AhDCli4Pd6Q6C3NwlMxIzsTFg+0wQ g067lJVOMwAjm2XttN5EAuOMHrh+5lp12t8IUgB0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726840AbgBSMTW (ORCPT ); Wed, 19 Feb 2020 07:19:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:42704 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726514AbgBSMTW (ORCPT ); Wed, 19 Feb 2020 07:19:22 -0500 Received: from localhost (unknown [106.201.32.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 58AAE206EF; Wed, 19 Feb 2020 12:19:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582114762; bh=TRqdYvf0Y/OocZGiHSaC6g7JfORCgxGpXUneLxerl7I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EEYzU+xJZ1mUDGzY+Wk5jX3Ao87PrhkgCkGcwFaNaIcf5f/sex90Bh/KrmfpGmk8W qI5UmzzrvAYoFJ//H9EZmMPKud+EdayAbvfuDJKFWwZ13l/2eg0msjL9yKtLrX+VrJ cFBMtMW9SdutaDRHM4gjHL4ynT3Lz9ECA0iM8ZNg= Date: Wed, 19 Feb 2020 17:49:18 +0530 From: Vinod Koul To: "Gustavo A. R. Silva" Cc: Dan Williams , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dmaengine: sa11x0: Replace zero-length array with flexible-array member Message-ID: <20200219121918.GJ2618@vkoul-mobl> References: <20200214171435.GA22930@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200214171435.GA22930@embeddedor> Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 14-02-20, 11:14, Gustavo A. R. Silva wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > This issue was found with the help of Coccinelle. Applied, thanks -- ~Vinod