From patchwork Thu Mar 19 19:50:46 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: 194357 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 54A54C4332D for ; Thu, 19 Mar 2020 20:15:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2787120776 for ; Thu, 19 Mar 2020 20:15:14 +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="GqMq4pnk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727136AbgCSUPN (ORCPT ); Thu, 19 Mar 2020 16:15:13 -0400 Received: from gateway32.websitewelcome.com ([192.185.145.102]:42830 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbgCSUPN (ORCPT ); Thu, 19 Mar 2020 16:15:13 -0400 X-Greylist: delayed 1464 seconds by postgrey-1.27 at vger.kernel.org; Thu, 19 Mar 2020 16:15:13 EDT Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway32.websitewelcome.com (Postfix) with ESMTP id AD784BBD9EB for ; Thu, 19 Mar 2020 14:50:48 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F1BojDGyKSl8qF1BojlwOe; Thu, 19 Mar 2020 14:50:48 -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=9Wv3jbj7V3+afTv1zkiRc6/kzb45qZM0mlCOpT5a6Vw=; b=GqMq4pnkbHIJSyj16jS/IXGon5 AEK/9C5A6VCq+zyljXQCj3ZPDd6r0vwMi+/18RhWGw3wWgiXIa0/QH9fFbUimH8EX8ZLLhraHmjHS snmVD9enTefCRw9Y1O1txFkR4D40WMSnEL8tPoDHUxDhN7oUCGn2s2nRt8huwibaYN9e3Abq9iixp vgWV6VI3P07cp9/Yb2VonQwMzLAI+Z+Hk0o917cOW297KF/7ozJnexvQcsrF1psDNFLBGY1KKeCX7 hWb2RYznbyyH9IwB4sr2lBO0J40VD0KxaadhtPCTSakKVqQ0Ir8sROTfJvSFpMYVXvxVfnZ7g6Gwz 4kIpaSow==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:52652 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF1Bm-000mHI-HG; Thu, 19 Mar 2020 14:50:46 -0500 Date: Thu, 19 Mar 2020 14:50:46 -0500 From: "Gustavo A. R. Silva" To: Dan Williams , Vishal Verma , Dave Jiang , Ira Weiny , "Rafael J. Wysocki" , Len Brown Cc: linux-nvdimm@lists.01.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] acpi: nfit.h: Replace zero-length array with flexible-array member Message-ID: <20200319195046.GA452@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: 1jF1Bm-000mHI-HG X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:52652 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 10 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@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/acpi/nfit/nfit.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h index 24241941181c..af09143ce403 100644 --- a/drivers/acpi/nfit/nfit.h +++ b/drivers/acpi/nfit/nfit.h @@ -144,32 +144,32 @@ struct nfit_spa { unsigned long ars_state; u32 clear_err_unit; u32 max_ars; - struct acpi_nfit_system_address spa[0]; + struct acpi_nfit_system_address spa[]; }; struct nfit_dcr { struct list_head list; - struct acpi_nfit_control_region dcr[0]; + struct acpi_nfit_control_region dcr[]; }; struct nfit_bdw { struct list_head list; - struct acpi_nfit_data_region bdw[0]; + struct acpi_nfit_data_region bdw[]; }; struct nfit_idt { struct list_head list; - struct acpi_nfit_interleave idt[0]; + struct acpi_nfit_interleave idt[]; }; struct nfit_flush { struct list_head list; - struct acpi_nfit_flush_address flush[0]; + struct acpi_nfit_flush_address flush[]; }; struct nfit_memdev { struct list_head list; - struct acpi_nfit_memory_map memdev[0]; + struct acpi_nfit_memory_map memdev[]; }; enum nfit_mem_flags {