From patchwork Thu Feb 13 01:08:51 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: 11379587 X-Patchwork-Delegate: jgg@ziepe.ca 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 9B4511395 for ; Thu, 13 Feb 2020 01:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A0982467D for ; Thu, 13 Feb 2020 01:29:22 +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="eOm+ryRM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729313AbgBMB3V (ORCPT ); Wed, 12 Feb 2020 20:29:21 -0500 Received: from gateway30.websitewelcome.com ([50.116.127.1]:49161 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729302AbgBMB3V (ORCPT ); Wed, 12 Feb 2020 20:29:21 -0500 X-Greylist: delayed 1223 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 20:29:20 EST Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 9391B16E9 for ; Wed, 12 Feb 2020 19:08:56 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 22zwjnqnxXVkQ22zwjBveb; Wed, 12 Feb 2020 19:08:56 -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=PMxecW0O4tdkPXbZnFnlCU+Xv/vOEnBfFdnNrRCVmMY=; b=eOm+ryRMFshQWqZPIC5nzWTTT5 NYoy8rPeuv9a+ALZXbLX093SJAZ7PHUep51y+OiKUbRHVffzTUEuFCEghnYGxhLmg5RY2OFFnaOmL Q5M+ciExfhUxzrfxCHyWREyePfOVRow6KUMW3jf++JiOA6NPmaRt54E1+iCGi//eN+CoR99x5nVzZ NwxHdNjayqX2GaQowodt1xZC18NLo83cMYTiwZRn4w1ao0CSxkv6Rcceop08O20iUwXmekl8Kw3jA wnYPisO9q7kfqNUNw8iRWy9pzzpUQqWBAOWecchmWn9zHHAwFbhsKGTinfTHQZd3j7NaK5Vek30zU 0ZHq9YcQ==; Received: from [200.68.141.42] (port=11053 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j22zu-003wxD-Mk; Wed, 12 Feb 2020 19:08:55 -0600 Date: Wed, 12 Feb 2020 19:08:51 -0600 From: "Gustavo A. R. Silva" To: Doug Ledford , Jason Gunthorpe Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] IB/mthca: Replace zero-length array with flexible-array member Message-ID: <20200213010851.GA13977@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: 1j22zu-003wxD-Mk X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.141.42]:11053 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@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/infiniband/hw/mthca/mthca_memfree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c index 78a48aea3faf..dc10376f09cb 100644 --- a/drivers/infiniband/hw/mthca/mthca_memfree.c +++ b/drivers/infiniband/hw/mthca/mthca_memfree.c @@ -58,7 +58,7 @@ struct mthca_user_db_table { u64 uvirt; struct scatterlist mem; int refcount; - } page[0]; + } page[]; }; static void mthca_free_icm_pages(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)