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=-13.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 0FE6CC352A4 for ; Thu, 13 Feb 2020 00:58:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D338420714 for ; Thu, 13 Feb 2020 00:58:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="rdqPEorI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729185AbgBMA6T (ORCPT ); Wed, 12 Feb 2020 19:58:19 -0500 Received: from gateway24.websitewelcome.com ([192.185.51.202]:23864 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729132AbgBMA6T (ORCPT ); Wed, 12 Feb 2020 19:58:19 -0500 X-Greylist: delayed 1359 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 19:58:18 EST Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 27CA026620 for ; Wed, 12 Feb 2020 18:35:39 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 22Tijc0kpEfyq22Tjjlf1B; Wed, 12 Feb 2020 18:35:39 -0600 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Type:MIME-Version:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=fj1EsM7KBtbLu9zEu9J4LZPmGuqoK3e/mqA04voGYHM=; b=rdqPEorIYVAWijtrjXYLTv7gxJ bUbshf+azRdrdo4/l5HJo9EST8kvqO+WPoCpoTxXEp6YdOib1G7B7Pf404o9JEr9Jn/r7RkmdeBb4 VV/ED7hO1B4eVQ1djz9gDGy+17mPhlNq9VXJaw6V3TDlmbbFziNWJa0UO2G/IPOxZBlqmDI7b9Wj2 jG1r42X5XQOnBnFYACDMVJJ2klKSIyEECne1QOw3ARe3DNSKLTJr6eGd7nup0v3WtXQBaxaIa9RLi Aum6exNjXQiTfdnxRAmHnCaQa8+F/4T/4CTPl398yaQmDhicm9mGbzSYoBYnP+qi9GhBetsC8klC5 N2pmV64w==; Received: from [200.68.141.42] (port=21619 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j22Th-003f1y-39; Wed, 12 Feb 2020 18:35:37 -0600 Date: Wed, 12 Feb 2020 18:35:35 -0600 From: "Gustavo A. R. Silva" To: Dan Williams , Vinod Koul , Masahiro Yamada Cc: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] dmaengine: uniphier-mdmac: replace zero-length array with flexible-array member Message-ID: <20200213003535.GA3269@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 200.68.141.42 X-Source-L: No X-Exim-ID: 1j22Th-003f1y-39 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.141.42]:21619 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 45 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@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] 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 --- drivers/dma/uniphier-mdmac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/uniphier-mdmac.c b/drivers/dma/uniphier-mdmac.c index 21b8f1131d55..618839df0748 100644 --- a/drivers/dma/uniphier-mdmac.c +++ b/drivers/dma/uniphier-mdmac.c @@ -68,7 +68,7 @@ struct uniphier_mdmac_device { struct dma_device ddev; struct clk *clk; void __iomem *reg_base; - struct uniphier_mdmac_chan channels[0]; + struct uniphier_mdmac_chan channels[]; }; static struct uniphier_mdmac_chan * -- 2.23.0