From patchwork Thu Feb 13 00:55:25 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: 11379555 X-Patchwork-Delegate: andy.shevchenko@gmail.com 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 23D6F109A for ; Thu, 13 Feb 2020 01:17:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0208121734 for ; Thu, 13 Feb 2020 01:17:49 +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="kRri0apn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729514AbgBMBRs (ORCPT ); Wed, 12 Feb 2020 20:17:48 -0500 Received: from gateway32.websitewelcome.com ([192.185.145.108]:28325 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729244AbgBMBRs (ORCPT ); Wed, 12 Feb 2020 20:17:48 -0500 X-Greylist: delayed 1337 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 20:17:47 EST Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway32.websitewelcome.com (Postfix) with ESMTP id E1A43B1F2C for ; Wed, 12 Feb 2020 18:55:29 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 22mvjCMpMAGTX22mvjOVXy; Wed, 12 Feb 2020 18:55:29 -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=hqjhoUQv+EY20/Nx26UEQj1s5SdWkNkvsRNYkR8wtW4=; b=kRri0apnQfzr8jDn1LQ/1qqf6S uUy2K5PghegCKCHnDYe5axuyvoF68R2tS5MSoimOy1eNA+sePzJCPjEndQg8KWK+er4OCmmaPCWhY qaDOoNmLPLuLnqDtiDXELFBZE2YIpymIWzur9IM7mDPsBsAgqcyKzBwCaVRVx8OEkzb9rNbPKHmoh WJ3v5QeeVJC5d8ANAMBkFXNaxWbMJh8cKUcJXZfE5OFYnCn7XjbjxcHqsRfZRKgasYY7qLFdZJgiX PG+GRzH6xrFeDkzPVd/O6ANDaO7RyzSm0jWOUpI6YVKlMuTvE5G/ory+e9TlxJw7ggQy3nouiYz/S nsP++9zA==; Received: from [200.68.141.42] (port=17615 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j22mt-003o7A-Jg; Wed, 12 Feb 2020 18:55:28 -0600 Date: Wed, 12 Feb 2020 18:55:25 -0600 From: "Gustavo A. R. Silva" To: Hans de Goede , Darren Hart , Andy Shevchenko Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] platform/x86: i2c-multi-instantiate: Replace zero-length array with flexible-array member Message-ID: <20200213005525.GA11420@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: 200.68.141.42 X-Source-L: No X-Exim-ID: 1j22mt-003o7A-Jg X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.141.42]:17615 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 80 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: platform-driver-x86-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@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 Reviewed-by: Hans de Goede --- drivers/platform/x86/i2c-multi-instantiate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/platform/x86/i2c-multi-instantiate.c b/drivers/platform/x86/i2c-multi-instantiate.c index ffb8d5d1eb5f..6acc8457866e 100644 --- a/drivers/platform/x86/i2c-multi-instantiate.c +++ b/drivers/platform/x86/i2c-multi-instantiate.c @@ -28,7 +28,7 @@ struct i2c_inst_data { struct i2c_multi_inst_data { int num_clients; - struct i2c_client *clients[0]; + struct i2c_client *clients[]; }; static int i2c_multi_inst_count(struct acpi_resource *ares, void *data)