From patchwork Thu Mar 19 21:21:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 11448113 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1122B17E6 for ; Thu, 19 Mar 2020 21:45:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E358D2076F for ; Thu, 19 Mar 2020 21:45:17 +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="u6VBBB0z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725768AbgCSVpR (ORCPT ); Thu, 19 Mar 2020 17:45:17 -0400 Received: from gateway30.websitewelcome.com ([192.185.197.25]:15756 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726785AbgCSVpR (ORCPT ); Thu, 19 Mar 2020 17:45:17 -0400 X-Greylist: delayed 1400 seconds by postgrey-1.27 at vger.kernel.org; Thu, 19 Mar 2020 17:45:16 EDT Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 7D9B26A80 for ; Thu, 19 Mar 2020 16:21:55 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F2bzjFN1VSl8qF2bzjo1Xp; Thu, 19 Mar 2020 16:21:55 -0500 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=Lubcu7p0qfGphDMpjrbgJu8a1pa8xGkLK9eIEZ6nuRE=; b=u6VBBB0zwTk1t5B8lmsQdzWIvV jsu7bhh3MomcXnRm7BVvH47RKt2VyGZheMSu92HRuJUYF8GA2shFL74mSzw6IHrVsxq46gELjwXMj ePx+t71k5fpmvkjeW8Ii5WjZxHuZUPc03LePlVEMPGb+yZMSRvFB3HPXSSZvHsAY5X0AxDHT/a01u pD9YZCOPrL9GEJvqWtI6HIp69oEyUpHIbu2VBjYqcJWwAs4DpAzEsqypS02XUynOWxjwUXQ0QksiQ DAiLd4WgnQLJuhMaplriSA/hZNKczV1q6G+hAlAgk9SuFK0ithmy/E8b4fOptnwpsDoRu94x635/m k1CO2F0g==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53266 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF2bx-001YAh-Vj; Thu, 19 Mar 2020 16:21:54 -0500 Date: Thu, 19 Mar 2020 16:21:53 -0500 From: "Gustavo A. R. Silva" To: Wu Hao , Moritz Fischer Cc: linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] fpga: dfl.h: Replace zero-length array with flexible-array member Message-ID: <20200319212153.GA5093@embeddedor.com> MIME-Version: 1.0 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: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jF2bx-001YAh-Vj X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53266 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 14 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-fpga-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fpga@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/fpga/dfl.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h index 4a9a33cd9979..74784d3cfe7c 100644 --- a/drivers/fpga/dfl.h +++ b/drivers/fpga/dfl.h @@ -235,7 +235,7 @@ struct dfl_feature_platform_data { int open_count; void *private; int num; - struct dfl_feature features[0]; + struct dfl_feature features[]; }; static inline