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=-1.0 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 B433BC49ED7 for ; Fri, 13 Sep 2019 08:36:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7733320830 for ; Fri, 13 Sep 2019 08:36:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387522AbfIMIg1 convert rfc822-to-8bit (ORCPT ); Fri, 13 Sep 2019 04:36:27 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:44650 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387424AbfIMIg1 (ORCPT ); Fri, 13 Sep 2019 04:36:27 -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-157-rwvhcf0CP16io7Sqh1YU_w-1; Fri, 13 Sep 2019 09:36:23 +0100 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; Fri, 13 Sep 2019 09:36:23 +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; Fri, 13 Sep 2019 09:36:23 +0100 From: David Laight To: 'Marcelo Ricardo Leitner' , Xin Long CC: network dev , "linux-sctp@vger.kernel.org" , Neil Horman , "davem@davemloft.net" Subject: RE: [PATCH net-next 5/5] sctp: add spt_pathcpthld in struct sctp_paddrthlds Thread-Topic: [PATCH net-next 5/5] sctp: add spt_pathcpthld in struct sctp_paddrthlds Thread-Index: AQHVZuRCrtt5derbnkaX0GdcwfdxAKck5i9wgAE3h4CAABM4AIACeq2egAChsYA= Date: Fri, 13 Sep 2019 08:36:22 +0000 Message-ID: References: <604e6ac718c29aa5b1a8c4b164a126b82bc42a2f.1568015756.git.lucien.xin@gmail.com> <9fc7ca1598e641cda3914840a4416aab@AcuMS.aculab.com> <1e5c3163e6c649b09137eeb62d193d87@AcuMS.aculab.com> <20190911125609.GC3499@localhost.localdomain> <20190912225154.GF3499@localhost.localdomain> In-Reply-To: <20190912225154.GF3499@localhost.localdomain> 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: rwvhcf0CP16io7Sqh1YU_w-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Marcelo Ricardo Leitner > Sent: 12 September 2019 23:52 ... > Here it is more visible. If net->...ps_retrans is disabled, remaining > fields (currently just this one, but as we are extending it now, we > have to think about the possibility of more as well) will be ignored, > we and we may not want that. The only real way to add additional fields is to change the name of the structure - that way recompiled programs still work. You could require that programs zero the entire structure - but that is difficult to verify. And, in this case, it seems that the default has to be 0xffff rather than 0 - which is, in itself, horrid. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)