From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249AbcEDMtI (ORCPT ); Wed, 4 May 2016 08:49:08 -0400 Received: from mail-wm0-f43.google.com ([74.125.82.43]:37330 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750986AbcEDMtG (ORCPT ); Wed, 4 May 2016 08:49:06 -0400 Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH net-next v2] block/drbd: use nla_put_u64_64bit() References: <57286F49.8050107@6wind.com> <1462268358-19044-1-git-send-email-nicolas.dichtel@6wind.com> <20160503100644.GE16459@soda.linbit> <20160503.120556.1317913903199470646.davem@davemloft.net> <20160504090529.GJ16459@soda.linbit> To: David Miller , netdev@vger.kernel.org, philipp.reisner@linbit.com, drbd-dev@lists.linbit.com, linux-kernel@vger.kernel.org From: Nicolas Dichtel Organization: 6WIND Message-ID: <5729EFBC.7040002@6wind.com> Date: Wed, 4 May 2016 14:49:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <20160504090529.GJ16459@soda.linbit> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 04/05/2016 11:05, Lars Ellenberg a écrit : [snip] > We don't have an "alignment problem" there, btw. > Last time I checked, we did work fine without this alignment magic, > we already take care of that, yes, even on affected architectures. The code adds several consecutive u64 attributes. The nl attribute header is 4 bytes, thus the full attribute length is 12 bytes. If the first u64 is aligned on 8 (nla_data()), the next one is not aligned on 8: it starts 12 bytes (8 (u64) + 4 (nl attr hdr)) after the previous u64.