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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C2FCAC3404D for ; Wed, 19 Feb 2020 07:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 933A2222D9 for ; Wed, 19 Feb 2020 07:14:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582096482; bh=vDPiNf+B0mf5gkVuFamqWW9yxNxqLXftA3SmpYPSvTE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=B7cWdoctrNDJQ73iKFrkL8YVprPC1EhnUXAgmJCrJk/miJuNMFyhl3Nm8bSXh7w16 75tJT7yKoDXi55DzZXB0cRg6xQ3ydykKQCUW9/VE00y/VtRDASfTrRPTA+UCIMhB3U aOSqJN2XW10tmGg445cdFzns+ldNMW1f0peSkkkE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726539AbgBSHOk (ORCPT ); Wed, 19 Feb 2020 02:14:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:49454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726336AbgBSHOk (ORCPT ); Wed, 19 Feb 2020 02:14:40 -0500 Received: from localhost (unknown [213.57.247.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2EA1A208C4; Wed, 19 Feb 2020 07:14:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582096479; bh=vDPiNf+B0mf5gkVuFamqWW9yxNxqLXftA3SmpYPSvTE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nuLNKQV1Cz08LTtUOVLhz7T4TSOwokH2pAiny1j1ceNqqD+M1ZkvwUaLXmAr7zSu4 9nECNM4SJ4uAoAsY7PBNTk43AIPiTBIHDNGJ3EG0gFRe5fMFslb5Iktmt71/EwjBGo 2Zt6l207M3t8eM6n0CfKlF9Ru11Y+d2S/Uv1Ujgg= Date: Wed, 19 Feb 2020 09:14:35 +0200 From: Leon Romanovsky To: "Gustavo A. R. Silva" Cc: Saeed Mahameed , "David S. Miller" , Boris Pismenny , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][next] net/mlx5e: Replace zero-length array with flexible-array member Message-ID: <20200219071435.GE15239@unreal> References: <20200218203114.GA27096@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200218203114.GA27096@embeddedor> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Feb 18, 2020 at 02:31:14PM -0600, Gustavo A. R. Silva wrote: > 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/net/ethernet/mellanox/mlx5/core/en.h | 2 +- > drivers/net/ethernet/mellanox/mlx5/core/fpga/ipsec.c | 2 +- > drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c | 2 +- > drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib.h | 4 ++-- > 4 files changed, 5 insertions(+), 5 deletions(-) > Thanks, applied to mlx5-next.