Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754715AbcCEM7F (ORCPT ); Sat, 5 Mar 2016 07:59:05 -0500 Received: from mail-wm0-f47.google.com ([74.125.82.47]:33808 "EHLO mail-wm0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750884AbcCEM7A (ORCPT ); Sat, 5 Mar 2016 07:59:00 -0500 MIME-Version: 1.0 In-Reply-To: <20160303161714.GA4133@kroah.com> References: <1456955489-18971-1-git-send-email-gustavo@padovan.org> <1457015837-7609-1-git-send-email-gustavo@padovan.org> <20160303161714.GA4133@kroah.com> Date: Sat, 5 Mar 2016 12:58:58 +0000 Message-ID: Subject: Re: [PATCH] staging/android: add flags member to sync ioctl structs From: Emil Velikov To: Greg Kroah-Hartman Cc: Gustavo Padovan , devel@driverdev.osuosl.org, Daniel Stone , Daniel Vetter , Riley Andrews , ML dri-devel , "Linux-Kernel@Vger. Kernel. Org" , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Gustavo Padovan , John Harrison Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1705 Lines: 46 Hi Greg, Allow me to chip in as well. On 3 March 2016 at 16:17, Greg Kroah-Hartman wrote: > On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote: >> From: Gustavo Padovan >> >> Play safe and add flags member to all structs. So we don't need to >> break API or create new IOCTL in the future if new features that requires >> flags arises. >> >> v2: check if flags are valid (zero, in this case) >> >> v3: return -EINVAL if flags are not zero'ed >> >> v4: add padding for 64-bit alignment >> >> v5: rebase to use only stacked sync_file_info > > Why are these vX things here in the changelog? > > And you just broke all existing userspace users of this code, why are > you allowed to do that? > In all honesty, isn't 'fluid ABI' one of the reasons behind staging ? That is how it was used by a few drivers in the past, at least. If the rules have changed and/or Android is special in that regard, we ought to make it perfectly clear so that people are aware from day 1. That aside, Android developers were clear that only internal, downstream components are using this code and they are OK with breaking the ABI [1]. Gustavo is in the process of rewriting their tests for upstream inclusion and he'll also update the Android side of things [2]. With those in mind, I think everything should be safe here. If you prefer to avoid the ABI break, which approach are you keen on - reassign new ioctl numbers (Rob suggestion) or use new header fence2.h (Daniel). Thank you Emil [1] https://lists.freedesktop.org/archives/dri-devel/2016-January/099592.html [2] https://lists.freedesktop.org/archives/dri-devel/2016-January/099726.html