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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 7B92FC7618B for ; Mon, 29 Jul 2019 10:39:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58E5B206BA for ; Mon, 29 Jul 2019 10:39:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728346AbfG2KjV convert rfc822-to-8bit (ORCPT ); Mon, 29 Jul 2019 06:39:21 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:39252 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbfG2KjU (ORCPT ); Mon, 29 Jul 2019 06:39:20 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-24-dISn8bX0OCytxGZ1hwsOwQ-1; Mon, 29 Jul 2019 11:39:17 +0100 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b::d117) by AcuMS.aculab.com (fd9f:af1c:a25b::d117) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 29 Jul 2019 11:39:16 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 29 Jul 2019 11:39:16 +0100 From: David Laight To: 'Qian Cai' , "vyasevich@gmail.com" , "nhorman@tuxdriver.com" , "marcelo.leitner@gmail.com" CC: "linux-sctp@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] net/sctp: fix GCC8+ -Wpacked-not-aligned warnings Thread-Topic: [PATCH] net/sctp: fix GCC8+ -Wpacked-not-aligned warnings Thread-Index: AQHVQ/TTkQHT5kEjjEefGhuj7/2hGabhauMA Date: Mon, 29 Jul 2019 10:39:16 +0000 Message-ID: <158b26b6f3b24164aceacd2428095315@AcuMS.aculab.com> References: <1564174659-21211-1-git-send-email-cai@lca.pw> In-Reply-To: <1564174659-21211-1-git-send-email-cai@lca.pw> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: dISn8bX0OCytxGZ1hwsOwQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qian Cai > Sent: 26 July 2019 21:58 > > There are a lot of those warnings with GCC8+ 64bit, > ... > Fix them by aligning the structures and fields to 8 bytes instead. ... > struct sctp_setpeerprim { > sctp_assoc_t sspp_assoc_id; > - struct sockaddr_storage sspp_addr; > -} __attribute__((packed, aligned(4))); > + struct sockaddr_storage sspp_addr __attribute__((aligned(8))); > +} __attribute__((packed, aligned(8))); What happens to this one if you change both to aligned(4) ? Much the same way as: struct { int a; long b __attribute__((aligned(4)); }; is only 12 bytes on (most) 64bit systems. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)