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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 7088DC38A2A for ; Thu, 7 May 2020 19:18:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 461DD24953 for ; Thu, 7 May 2020 19:18:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588879084; bh=6u2Zjd4cCAJplBkIJArkC26yIzl29BGwwVH3o2xHtus=; h=Date:From:To:Cc:Subject:List-ID:From; b=2TrGsTeFJNIrBDJPoUm4p0FI8AAm0Q0YpExryDOF8iZ8ULWmgi0He5I6+bjEulcVo QaWAtRxyBq0dHlM/S2rnSaJlKtVY7BIuHpCNCDsu9b2kVbm71EpdPvMG21+jIb1Aog jK7FSx3ZmjYlhW0A/VD5kJ1KHNK62cYRRuiKj7S0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728681AbgEGTSD (ORCPT ); Thu, 7 May 2020 15:18:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:41002 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726367AbgEGTSC (ORCPT ); Thu, 7 May 2020 15:18:02 -0400 Received: from embeddedor (unknown [189.207.59.248]) (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 B0CF821835; Thu, 7 May 2020 19:18:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588879082; bh=6u2Zjd4cCAJplBkIJArkC26yIzl29BGwwVH3o2xHtus=; h=Date:From:To:Cc:Subject:From; b=KJ7s41EA/KoUExDhcHun9qGSDWEpgm/fTIP9T9CzHUw4Jhqsz64KiFgt9cTc+tzQ2 a/1gXi4RyMPG7UC9ubhXx19jnsIbGpm6KoDr//HwybVANQgxObEtbnMIVvhgeq4bRF Al/JgIZkn/n4NLqevOxa/qXJnx9tV+tHjHLz/VFI= Date: Thu, 7 May 2020 14:22:28 -0500 From: "Gustavo A. R. Silva" To: Liam Girdwood , Mark Brown Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: [PATCH] ASoC: soc-core: Replace zero-length array with flexible-array Message-ID: <20200507192228.GA16355@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva --- include/sound/soc-dapm.h | 2 +- include/sound/soc.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/sound/soc-dapm.h b/include/sound/soc-dapm.h index 08495f8d86dc..cc3dcb815282 100644 --- a/include/sound/soc-dapm.h +++ b/include/sound/soc-dapm.h @@ -689,7 +689,7 @@ struct snd_soc_dapm_context { /* A list of widgets associated with an object, typically a snd_kcontrol */ struct snd_soc_dapm_widget_list { int num_widgets; - struct snd_soc_dapm_widget *widgets[0]; + struct snd_soc_dapm_widget *widgets[]; }; #define for_each_dapm_widgets(list, i, widget) \ diff --git a/include/sound/soc.h b/include/sound/soc.h index 13458e4fbb13..3e14442de2ec 100644 --- a/include/sound/soc.h +++ b/include/sound/soc.h @@ -1167,7 +1167,7 @@ struct snd_soc_pcm_runtime { unsigned int fe_compr:1; /* for Dynamic PCM */ int num_components; - struct snd_soc_component *components[0]; /* CPU/Codec/Platform */ + struct snd_soc_component *components[]; /* CPU/Codec/Platform */ }; /* see soc_new_pcm_runtime() */ #define asoc_rtd_to_cpu(rtd, n) (rtd)->dais[n]