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=-5.8 required=3.0 tests=BAYES_00,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 209B2C4338F for ; Wed, 18 Aug 2021 16:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02D9460EBC for ; Wed, 18 Aug 2021 16:22:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231151AbhHRQXX (ORCPT ); Wed, 18 Aug 2021 12:23:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48864 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229454AbhHRQXV (ORCPT ); Wed, 18 Aug 2021 12:23:21 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D591C061764; Wed, 18 Aug 2021 09:22:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HwP/nMh1cO8cF7GObYL+nv9FmhI1pvtnORa3FRBGMnE=; b=dRRewrHMhqhelJiynY40+Jt/8X CEXQEFp13ZKVcdj7C+ptF0cC1ssJADzlz1h6gin+O7U+8mzDpwt0p4fDsGKUuspm4w+ndmOlwhElk IDh50Gk8NXoNBZ0hgxx02xW1ZrBn8n5p+GjmjrdPyckwuJ1RXtLCUMmrGBQs3DCEIgqGDNH3cNgt/ vccEXuajJuGJE1wwtPzSz3Xl9xcSxCo9jDFrqm+25yU/Q69SQ+fUnCX+MGxqRppXjmptDurJDgW5N 0ni9VP89jyoJLu7O8BLM7Oq3lYLkw4BJbldk4F8Tl/2NknLBTTPIPJx8bkHiEdIftbwGreIpKAzPp j0A+dhhg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mGOIu-00421p-8q; Wed, 18 Aug 2021 16:20:50 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id C955F981DD4; Wed, 18 Aug 2021 18:20:34 +0200 (CEST) Date: Wed, 18 Aug 2021 18:20:34 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: =?iso-8859-1?Q?Andr=E9?= Almeida , Ingo Molnar , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior , kernel@collabora.com, krisman@collabora.com, linux-api@vger.kernel.org, libc-alpha@sourceware.org, mtk.manpages@gmail.com, Davidlohr Bueso Subject: Re: [PATCH 2/4] futex2: Implement vectorized wait Message-ID: <20210818162034.GA26408@worktop.programming.kicks-ass.net> References: <20210805190405.59110-1-andrealmeid@collabora.com> <20210805190405.59110-3-andrealmeid@collabora.com> <87v94310gm.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v94310gm.ffs@tglx> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 18, 2021 at 01:00:57PM +0200, Thomas Gleixner wrote: > > +/** > > + * struct futex_waitv - A waiter for vectorized wait > > + * @val: Expected value at uaddr > > + * @uaddr: User address to wait on > > + * @flags: Flags for this waiter > > + */ > > +struct futex_waitv { > > + __u64 val; > > Again. Why u64? So I think the idea was that if we're going to do new syscalls, we should cater for future extentions, one of which was 64bit futexes (for 64bit archs) (along with u{8,16,32}) The previous set of patches implemented a more complete replacement ABI -- which I rather liked, however the implementation was completely disjoint from the existing futexes, which was a non-starter for me. Anyway, yes, current futexes are u32, but if we want to ever do u64 futexes, we should either do this syscall with a u64, or already plan to retire the whole syscall. Obiously this would've made good Changelog material, but alas it wasn't there.