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=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 EE6CBC4743F for ; Tue, 8 Jun 2021 13:27:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D25CD6128D for ; Tue, 8 Jun 2021 13:27:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233023AbhFHN3p (ORCPT ); Tue, 8 Jun 2021 09:29:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:59520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233025AbhFHN3m (ORCPT ); Tue, 8 Jun 2021 09:29:42 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EBA3E61009; Tue, 8 Jun 2021 13:27:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623158855; bh=D+lp5Yp4s5pc/+bwbwvj8F8yRt2z7XluZm2R3r9rwME=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=I4xnn7D6nO1wKo/fcg4fYE7aKLZskLjgMWj8e6jI0ieF+m3eIIHqCO5Ya2Nk0cGFj JNGktwLoKyEit5X+ZPkfGlWItX7AMCktx4v45UkoNeMv63QETKcX/U3LLdKS9yOPbo YzUVGGE/Ublh+2NN8Oh7QZJCXFTGsP/neYQXLBj0= Date: Tue, 8 Jun 2021 15:27:32 +0200 From: Greg KH To: Andrey Semashev Cc: Nicholas Piggin , =?iso-8859-1?Q?Andr=E9?= Almeida , acme@kernel.org, Sebastian Andrzej Siewior , corbet@lwn.net, Davidlohr Bueso , Darren Hart , fweimer@redhat.com, joel@joelfernandes.org, kernel@collabora.com, krisman@collabora.com, libc-alpha@sourceware.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, malteskarupke@fastmail.fm, Ingo Molnar , Peter Zijlstra , pgriffais@valvesoftware.com, Peter Oskolkov , Steven Rostedt , shuah@kernel.org, Thomas Gleixner , z.figura12@gmail.com Subject: Re: [PATCH v4 00/15] Add futex2 syscalls Message-ID: References: <1622853816.mokf23xgnt.astroid@bobo.none> <6d8e3bb4-0cef-b991-9a16-1f03d10f131d@gmail.com> <1622980258.cfsuodze38.astroid@bobo.none> <1623114630.pc8fq7r5y9.astroid@bobo.none> <8fa8b7fd-58ae-9467-138d-4ff4f32f68f7@gmail.com> <3fca0afa-d9db-a176-aad1-ff7db21ba4a2@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3fca0afa-d9db-a176-aad1-ff7db21ba4a2@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 08, 2021 at 04:18:42PM +0300, Andrey Semashev wrote: > On 6/8/21 3:35 PM, Greg KH wrote: > > On Tue, Jun 08, 2021 at 03:06:48PM +0300, Andrey Semashev wrote: > > > On 6/8/21 2:13 PM, Greg KH wrote: > > > > > > So what's keeping the futex2 code from doing all that futex1 does so > > > > that the futex1 code can be deleted internally? > > > > > > I think, André will answer this, but my guess is, as stated above, this is a > > > lot of work and time while the intermediate version is already useful. > > > > useful to who? I still do not understand what users will be needing > > this. All I can tell is a single userspace program wants to use it, and > > that is a fork from the real project it was based on and that the > > maintainers have no plan to merge it back. > > > > So who does need/want this? > > I mentioned C++ std::atomic and Boost.Atomic before. Those need variable > sized futexes. And has anyone converted them to use this new api to see if it works well or not? As was pointed out to me numerous times when I tried to propose readfile(), you need a real user that can show and prove it is needed before we can take new syscalls, especially complex beasts like this one. thanks, greg k-h