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,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 71FA1C3F2D1 for ; Thu, 5 Mar 2020 10:54:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41F04208C3 for ; Thu, 5 Mar 2020 10:54:07 +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="f24mJ78x" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727069AbgCEKyG (ORCPT ); Thu, 5 Mar 2020 05:54:06 -0500 Received: from gateway32.websitewelcome.com ([192.185.145.181]:35450 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725880AbgCEKyG (ORCPT ); Thu, 5 Mar 2020 05:54:06 -0500 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway32.websitewelcome.com (Postfix) with ESMTP id 4389E12D27 for ; Thu, 5 Mar 2020 04:54:05 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 9o8jjLCo1Efyq9o8jjP1sU; Thu, 05 Mar 2020 04:54:05 -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=FaEd7taemh650scF/FKlDe95GL6rqrDcsV1+ENwoAYo=; b=f24mJ78xbf1EfsW+xIzeAqlquK E6JU5oxcoHQ+vdMzeLJhMCMKgcOUb/FqutbKiYFFgIHiIo4Q7catoDYtyq2lxHrO3H/ozwIw7c7Bo tyb4OV0di9NN8eFHHc+JlrgesLpI69f0XD5a3kYQLME0v2+5rh4qCfJQhUx1DA1E+tlAfnz9aVV2z kiwqF8mhIlgwi2SMBi0amMDMPFBTpAZt7KDjzudY9GvCzOYw1txTPqLJrimhO6cd7Uat5B2sNegND jzTPMWFvqePG8y8/B5mNSNjnyX0ITxIoH4EquTpF/KSpJ5506vdB3hLGLap7RFsGVxQvLMYgDGKBu oM32RlwA==; Received: from [201.166.169.220] (port=31563 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j9o8f-003gJu-CY; Thu, 05 Mar 2020 04:54:01 -0600 Date: Thu, 5 Mar 2020 04:57:07 -0600 From: "Gustavo A. R. Silva" To: Eric Anholt , David Airlie , Daniel Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] drm/vc4/vc4_drv.h: Replace zero-length array with flexible-array member Message-ID: <20200305105707.GA19261@embeddedor> 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: 201.166.169.220 X-Source-L: No X-Exim-ID: 1j9o8f-003gJu-CY X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.169.220]:31563 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 31 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes 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] 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/gpu/drm/vc4/vc4_drv.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h index f90c0d08e740..5ecb8b4a48a1 100644 --- a/drivers/gpu/drm/vc4/vc4_drv.h +++ b/drivers/gpu/drm/vc4/vc4_drv.h @@ -65,7 +65,7 @@ struct vc4_perfmon { * Note that counter values can't be reset, but you can fake a reset by * destroying the perfmon and creating a new one. */ - u64 counters[0]; + u64 counters[]; }; struct vc4_dev { -- 2.25.0