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=-3.8 required=3.0 tests=BAYES_00, 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 118EFC433DB for ; Sun, 17 Jan 2021 18:33:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC5E722227 for ; Sun, 17 Jan 2021 18:33:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730015AbhAQSdl convert rfc822-to-8bit (ORCPT ); Sun, 17 Jan 2021 13:33:41 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:55539 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729935AbhAQSdS (ORCPT ); Sun, 17 Jan 2021 13:33:18 -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-165-qzM2FzfaOG6j69VeZBrcNw-1; Sun, 17 Jan 2021 18:31:37 +0000 X-MC-Unique: qzM2FzfaOG6j69VeZBrcNw-1 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; Sun, 17 Jan 2021 18:31:36 +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; Sun, 17 Jan 2021 18:31:36 +0000 From: David Laight To: 'Christoph Hellwig' , Andy Lutomirski CC: Arnd Bergmann , Ryan Houdek , Catalin Marinas , Will Deacon , Alexander Viro , Arnd Bergmann , Christian Brauner , Andrew Morton , Minchan Kim , Aleksa Sarai , Sargun Dhillon , Miklos Szeredi , Vincenzo Frascino , Amanieu d'Antras , Willem de Bruijn , YueHaibing , Xiaoming Ni , Heiko Carstens , "Eric W. Biederman" , Joe Perches , Jan Kara , David Rientjes , "Arnaldo Carvalho de Melo" , "David S. Miller" , Linux ARM , "linux-kernel@vger.kernel.org" , Linux FS-devel Mailing List , Linux API , linux-arch Subject: RE: [PATCH] Adds a new ioctl32 syscall for backwards compatibility layers Thread-Topic: [PATCH] Adds a new ioctl32 syscall for backwards compatibility layers Thread-Index: AQHW6+b/d1V6Thk8U0iiUgMFo8hTJqosJEIw Date: Sun, 17 Jan 2021 18:31:36 +0000 Message-ID: References: <20210106064807.253112-1-Sonicadvance1@gmail.com> <20210116090721.GA30277@lst.de> In-Reply-To: <20210116090721.GA30277@lst.de> Accept-Language: en-GB, 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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Hellwig > Sent: 16 January 2021 09:07 ... > > I personally would like to see in_compat_syscall() go away, > > but some other people (Hi, Christoph!) disagree, and usage seems to be > > increasing, not decreasing. > > I'm absolutely against it going away. in_compat_syscall helped to > remove so much crap compared to the explicit compat syscalls. The only other real option is to pass the 'syscall type' explicitly through all the layers into every piece of code that might need it. So passing it as a 'parameter' that is (probably) current->syscall_type does make sense. It might even make sense have separate bits for the required emulations. So you'd have separate bits for '32bit pointers' and '64bit items 32bit aligned' (etc). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)