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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F248CC4332F for ; Wed, 30 Mar 2022 17:38:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349394AbiC3Rjv (ORCPT ); Wed, 30 Mar 2022 13:39:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344245AbiC3Rjt (ORCPT ); Wed, 30 Mar 2022 13:39:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F47FD4CB8; Wed, 30 Mar 2022 10:38:03 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1E3C2B81DF5; Wed, 30 Mar 2022 17:38:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCA82C34110; Wed, 30 Mar 2022 17:37:59 +0000 (UTC) Date: Wed, 30 Mar 2022 13:37:58 -0400 From: Steven Rostedt To: Mathieu Desnoyers Cc: linux-kernel , Beau Belgrave , Masami Hiramatsu , linux-trace-devel , bpf , netdev , Alexei Starovoitov , Linus Torvalds Subject: Re: [PATCH] tracing: Set user_events to BROKEN Message-ID: <20220330133758.712768db@gandalf.local.home> In-Reply-To: <1546405229.199729.1648659253425.JavaMail.zimbra@efficios.com> References: <20220329222514.51af6c07@gandalf.local.home> <1546405229.199729.1648659253425.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 30 Mar 2022 12:54:13 -0400 (EDT) Mathieu Desnoyers wrote: > ----- On Mar 29, 2022, at 10:25 PM, rostedt rostedt@goodmis.org wrote: > > > From: "Steven Rostedt (Google)" > > > > After being merged, user_events become more visible to a wider audience > > that have concerns with the current API. It is too late to fix this for > > this release, but instead of a full revert, just mark it as BROKEN (which > > prevents it from being selected in make config). Then we can work finding > > a better API. If that fails, then it will need to be completely reverted. > > Hi Steven, > > What are the constraints for changing a uapi header after it has been present > in a kernel release ? > > If we are not ready to commit to an ABI, perhaps it would be safer to ensure > that include/uapi/linux/user_events.h is not installed with the uapi headers > until it's ready. > Linus may say otherwise, but from what I understand is that we can not break a user space application from one release to the next. That means, the only way to break something is if it is actually using something in binary form. I can not think of a situation where a header file is useful if the API it's used for is not available. Thus do we really need to hide it? What applications will use a header file that has no interface for it? I do not see the need to remove the uapi if the API for that structure is not available yet. -- Steve