From patchwork Thu Mar 19 23:10:58 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: 1258504 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=devicetree-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=embeddedor.com header.i=@embeddedor.com header.a=rsa-sha256 header.s=default header.b=tMqhN3RA; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48k2hV0rclz9sRR for ; Fri, 20 Mar 2020 10:11:06 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727258AbgCSXLE (ORCPT ); Thu, 19 Mar 2020 19:11:04 -0400 Received: from gateway21.websitewelcome.com ([192.185.46.113]:25233 "EHLO gateway21.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727237AbgCSXLB (ORCPT ); Thu, 19 Mar 2020 19:11:01 -0400 Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway21.websitewelcome.com (Postfix) with ESMTP id A4CC6400CD18C for ; Thu, 19 Mar 2020 18:11:00 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F4JYjHOINSl8qF4JYjq1mp; Thu, 19 Mar 2020 18:11:00 -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=Nw1HXisaj8hrwGMx9cIEuySFdpe+gJCRN7+yZDygmy4=; b=tMqhN3RA73L+F2ZRlm7NB4Fyj4 4itUoViCKDmT9ey287FK/CactohMeIlF64mnT9cbbBQnGxHpbK1VDoD+zHm3A4oneWutUjekYPRzT t7DCwlz1tTaPGFviA/0cjC2sQV5MI699d8U37Y9C5F/e7XwGFTcY0cAZHxW4yQUweU4AH8LeT58GQ yZwgoZPVs939QoQmVF6F0I/AA5m1xZhttviETUgFWHLM0F9aRSNbkuU92Gnk3fEX7upE/kMHypskO fAqo0M2jaQXu+2xS6+PqeLzxrhpO4YuDPVicpOy3W2x/o6PQ/sPtqjK4igAfCxKE0S4qPd097nv0n rcD/i0fg==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:54050 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF4JX-002R3V-3N; Thu, 19 Mar 2020 18:10:59 -0500 Date: Thu, 19 Mar 2020 18:10:58 -0500 From: "Gustavo A. R. Silva" To: Rob Herring , Frank Rowand Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] of: of_private.h: Replace zero-length array with flexible-array member Message-ID: <20200319231058.GA18540@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: 1jF4JX-002R3V-3N X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:54050 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 25 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@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/of/of_private.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 207863c151a5..edc682249c00 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -24,7 +24,7 @@ struct alias_prop { const char *alias; struct device_node *np; int id; - char stem[0]; + char stem[]; }; #if defined(CONFIG_SPARC)