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 E5D34C432C0 for ; Tue, 26 Nov 2019 10:13:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C457D206BF for ; Tue, 26 Nov 2019 10:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727838AbfKZKNo convert rfc822-to-8bit (ORCPT ); Tue, 26 Nov 2019 05:13:44 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:20539 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727388AbfKZKNo (ORCPT ); Tue, 26 Nov 2019 05:13:44 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-68-quipjFAFM3icMji5ZqiO4A-1; Tue, 26 Nov 2019 10:13:38 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Tue, 26 Nov 2019 10:13:37 +0000 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; Tue, 26 Nov 2019 10:13:37 +0000 From: David Laight To: 'Fenghua Yu' , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Andy Lutomirski , Peter Zijlstra , Ashok Raj , Tony Luck , Ravi V Shankar CC: linux-kernel , x86 Subject: RE: [PATCH v2 0/4] Fix some 4-byte vs. 8-byte alignment issues in atomic bit operations Thread-Topic: [PATCH v2 0/4] Fix some 4-byte vs. 8-byte alignment issues in atomic bit operations Thread-Index: AQHVo8bnUSfQXTuB6k6xiK+0nu6MoaedOrpg Date: Tue, 26 Nov 2019 10:13:37 +0000 Message-ID: <965b5dcf35b54f8b96008a82e6d581c1@AcuMS.aculab.com> References: <1574710984-208305-1-git-send-email-fenghua.yu@intel.com> In-Reply-To: <1574710984-208305-1-git-send-email-fenghua.yu@intel.com> 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: quipjFAFM3icMji5ZqiO4A-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: Fenghua Yu > Sent: 25 November 2019 19:43 ... > Change Log: > v2: > - Remove patch 1 and 3 in v1 because they are in the tip tree already. > - Add new patches 2-4 per David Laight's comments: > https://lore.kernel.org/lkml/e7c75de9191847ed98c573f9ad871518@AcuMS.aculab.com/ > Running "grep -r --include '*.[ch]' '_bit([^(]*, *([^)]*\*)' ." > returns about 200 results. Most of them don't have split lock issues. Except that any code that has to cast the long[] array argument to any of the bitops functions is almost certainly broken in some way or other. At best it is relying on accidental alignment of whatever address it is passing to avoid alignment faults (for general misaligned accesses). In other cases attempting to run the code on a BE system will update the wrong bits - potentially in some other member of the structure. Now, you might say that 'this code is LE only', but at some point it might get used on a BE system. So all of those 200 results need fixing to remove the casts. Just using the unblocked __bit_xxx() functions doesn't fix all the problems. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)