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 ED859C4363A for ; Mon, 26 Oct 2020 09:46:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA56622409 for ; Mon, 26 Oct 2020 09:46:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1768346AbgJZJqW convert rfc822-to-8bit (ORCPT ); Mon, 26 Oct 2020 05:46:22 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:44186 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1768336AbgJZJqV (ORCPT ); Mon, 26 Oct 2020 05:46:21 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mtapsc-6-JpohbFICN5eunT0tPS-E1w-1; Mon, 26 Oct 2020 09:46:17 +0000 X-MC-Unique: JpohbFICN5eunT0tPS-E1w-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; Mon, 26 Oct 2020 09:46:17 +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; Mon, 26 Oct 2020 09:46:17 +0000 From: David Laight To: 'Stefano Garzarella' CC: Colin King , "David S . Miller" , Jakub Kicinski , "netdev@vger.kernel.org" , "kernel-janitors@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] vsock: ratelimit unknown ioctl error message Thread-Topic: [PATCH] vsock: ratelimit unknown ioctl error message Thread-Index: AQHWqUY0CPRviIGx7UytnIgbPi7/0amltMKAgAPgtgCAAAejEIAACBeAgAAAcdA= Date: Mon, 26 Oct 2020 09:46:17 +0000 Message-ID: <3e34e4121f794355891fd7577c9dfbc0@AcuMS.aculab.com> References: <20201023122113.35517-1-colin.king@canonical.com> <20201023140947.kurglnklaqteovkp@steredhat> <20201026084300.5ag24vck3zeb4mcz@steredhat> <20201026093917.5zgginii65pq6ezd@steredhat> In-Reply-To: <20201026093917.5zgginii65pq6ezd@steredhat> 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: netdev@vger.kernel.org From: Stefano Garzarella > Sent: 26 October 2020 09:39 > > On Mon, Oct 26, 2020 at 09:13:23AM +0000, David Laight wrote: > >From: Stefano Garzarella > >> Sent: 26 October 2020 08:43 > >... > >> >Isn't the canonical error for unknown ioctl codes -ENOTTY? > >> > > >> > >> Oh, thanks for pointing that out! > >> > >> I had not paid attention to the error returned, but looking at it I > >> noticed that perhaps the most appropriate would be -ENOIOCTLCMD. > >> In the ioctl syscall we return -ENOTTY, if the callback returns > >> -ENOIOCTLCMD. > >> > >> What do you think? > > > >It is 729 v 443 in favour of ENOTTY (based on grep). > > Under net/ it is 6 vs 83 in favour of ENOIOCTLCMD. > > > > >No idea where ENOIOCTLCMD comes from, but ENOTTY probably > >goes back to the early 1970s. > > Me too. > > > > >The fact that the ioctl wrapper converts the value is a good > >hint that userspace expects ENOTTY. > > Agree on that, but since we are not interfacing directly with userspace, > I think it is better to return the more specific error (ENOIOCTLCMD). I bet Linux thought it could use a different error code then found that 'unknown ioctl' was spelt ENOTTY. Back in the old days error values were probably almost unique. strerror(EAGIAN) was "No more processes" for a long time! David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)