From patchwork Thu Feb 27 19:07:21 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: 11409531 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 0EEF114D5 for ; Thu, 27 Feb 2020 19:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E28B8246A5 for ; Thu, 27 Feb 2020 19:04:33 +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="jP1MdHKV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729563AbgB0TEd (ORCPT ); Thu, 27 Feb 2020 14:04:33 -0500 Received: from gateway21.websitewelcome.com ([192.185.45.38]:14031 "EHLO gateway21.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729385AbgB0TEd (ORCPT ); Thu, 27 Feb 2020 14:04:33 -0500 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway21.websitewelcome.com (Postfix) with ESMTP id 27F83400CFD8F for ; Thu, 27 Feb 2020 13:04:32 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7OSWjfNuOXVkQ7OSWj0QWD; Thu, 27 Feb 2020 13:04:32 -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=a4cGODhzoqFN7XGLNvkdgu9vu9YdHDnB4q9Ykb1Vc28=; b=jP1MdHKVsh/wfVAve847rc8Ls3 kR+ScU0Uk04FU9J/wDGSWCDwGFdVWrtTaAfyxk4nUV1UFAP9qNiS8ddxKw6kODNjFx/FhOYSX9fsz 1VEovtHNx5zZWaoOUqWYrZSKltm/DNXUt4H9ZpTPWufPNJC4rctUvxyrl+OQ4Wf7ovKoVaZ/+SWA+ KFXs9gQuSYptNOwVwJ7SQLFxMhe6w6SctRNe7vsmoRzxDG63HBFWbVQbhSlDcNV5sCFoaUDw07zjA qScg/7rG08/iHVju0kdYY9QUVS1VriidIDn0w0ni9Tv6DzxEb1FUjtOQj4uSOrSCGKXgOh+sU9v5G R5E8Um0g==; Received: from [201.162.168.186] (port=28892 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7OST-004Cgc-KG; Thu, 27 Feb 2020 13:04:30 -0600 Date: Thu, 27 Feb 2020 13:07:21 -0600 From: "Gustavo A. R. Silva" To: "Rafael J. Wysocki" Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] powercap: idle_inject: Replace zero-length array with flexible-array member Message-ID: <20200227190721.GA19083@embeddedor> 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: 201.162.168.186 X-Source-L: No X-Exim-ID: 1j7OST-004Cgc-KG X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.168.186]:28892 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@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] Lastly, fix the following checkpatch warning: WARNING: Prefer 'unsigned long' over 'unsigned long int' as the int is unnecessary + unsigned long int cpumask[]; 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/powercap/idle_inject.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c index cd1270614cc6..e9bbd3c42eef 100644 --- a/drivers/powercap/idle_inject.c +++ b/drivers/powercap/idle_inject.c @@ -67,7 +67,7 @@ struct idle_inject_device { struct hrtimer timer; unsigned int idle_duration_us; unsigned int run_duration_us; - unsigned long int cpumask[0]; + unsigned long cpumask[]; }; static DEFINE_PER_CPU(struct idle_inject_thread, idle_inject_thread);