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 ADFB1C4332D for ; Thu, 19 Mar 2020 22:15:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7E66420663 for ; Thu, 19 Mar 2020 22:15:38 +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="Te9Rcnks" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727399AbgCSWPi (ORCPT ); Thu, 19 Mar 2020 18:15:38 -0400 Received: from gateway20.websitewelcome.com ([192.185.47.18]:40603 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727297AbgCSWPi (ORCPT ); Thu, 19 Mar 2020 18:15:38 -0400 X-Greylist: delayed 1428 seconds by postgrey-1.27 at vger.kernel.org; Thu, 19 Mar 2020 18:15:37 EDT Received: from cm12.websitewelcome.com (cm12.websitewelcome.com [100.42.49.8]) by gateway20.websitewelcome.com (Postfix) with ESMTP id 57418400CCC8E for ; Thu, 19 Mar 2020 15:36:20 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F34vjzTz61s2xF34vjhrRL; Thu, 19 Mar 2020 16:51:49 -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=JEikPqF6NxVfkvZjVP+cGq3DgK8l2GBx5Tnc9nIqPVg=; b=Te9RcnksN6yMkoH3gzTZsI6FL5 lrC4AYhR9cB28XuBX4opT8qJPThImwhGDa83tJ/WdSiA1IKTYXtxwNQR/xhHY9BvT2a8aJKaCrg8k V0XCdiIE+1OJU+NsQwnPb+Or2Mw4gBQSIvn4fdcjpvk+V/Pc67TCILpiS4VKeQjNIsVFvuJ0kv5rv FoDBj3i810Ug1Eefcv6d2i4RNJDU4pTnmBDezNEf14buSaWaSCmL13s01irthevxWHMXP8fHwDkEG 96QB35O0EqW3U4yShNQ35bO/YfkOgMUoRX2dQgNOvgMBZzKoBeds1Gi22D5T2a+hyOjKhqCGDg2NT Ws9VYm3Q==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53540 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF34s-001noC-VK; Thu, 19 Mar 2020 16:51:47 -0500 Date: Thu, 19 Mar 2020 16:51:46 -0500 From: "Gustavo A. R. Silva" To: Jacek Anaszewski , Pavel Machek , Dan Murphy Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] leds: leds-pwm: Replace zero-length array with flexible-array member Message-ID: <20200319215146.GA24054@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: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jF34s-001noC-VK X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53540 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 73 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@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/leds/leds-pwm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c index 9111cdede0ee..31ac44dfb926 100644 --- a/drivers/leds/leds-pwm.c +++ b/drivers/leds/leds-pwm.c @@ -28,7 +28,7 @@ struct led_pwm_data { struct led_pwm_priv { int num_leds; - struct led_pwm_data leds[0]; + struct led_pwm_data leds[]; }; static int led_pwm_set(struct led_classdev *led_cdev, -- 2.23.0