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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 6EE8AC3F2CE for ; Wed, 4 Mar 2020 20:14:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 436D620870 for ; Wed, 4 Mar 2020 20:14:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="yGz2amRr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727137AbgCDUOp (ORCPT ); Wed, 4 Mar 2020 15:14:45 -0500 Received: from mail-io1-f65.google.com ([209.85.166.65]:39282 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726561AbgCDUOo (ORCPT ); Wed, 4 Mar 2020 15:14:44 -0500 Received: by mail-io1-f65.google.com with SMTP id h3so3852274ioj.6 for ; Wed, 04 Mar 2020 12:14:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=nAztYb774WsRpkB+kATuYDeAaIxkEfk/WJzTJiyRWW0=; b=yGz2amRrTZYm7zqKyq6bbG+n9kOXzqpyGSHZmSlwWip1EMmuT/8oh5Nxs79FLAJJZZ HP5KTCGzbG3INvyTt6iVZry1fHVz4D1GG6Efd1Q+K6rbNBxUAmkSAxQkeJLhKgZJUreH Isz8o65RH8kPGJU9QlcvFYGOtBjlJZN4T7PBMwU+KM2hSgJW+i338cL/VsEnIu+t7UG0 V9iuRN0YJXXwQ/eoYaqh/arqzQPpvKaWndldtTQbAk0Mlv6jECaZXj3NgIQIc9zJQ285 XpfM7FYiqQktu7jRxhbkxx+uESJ6diop7OqrrD/F+aQdbQDboJmq+LuiLzrP52Sg/m66 qBDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=nAztYb774WsRpkB+kATuYDeAaIxkEfk/WJzTJiyRWW0=; b=uBU9jNUW/lcjEPedPDapKh2ttXaEH4pValYnc+W3pdrndmOuLm4owJ8ZBDti1blO9U b3g8xwVL6uo//6Y1Z1hxV8uOG/cBe5WeBPOObfJaPdhMIxbAqAMDVcv7BIEuzYwpuwkW rYkomEkWbP9793EKRBWcWeTKbAIHEGalnxs6WFpYoOrcrjPITQZ7XPdpMJ+C+pkinpdS UXsMfHLg+Dy6MZaKReXuGlMEdxowYRTtdHhkCD4hlpwIOk7mEdJlp+A+TyJz1lrr3R7v UCIW/a98WxMvGcreOekOSa9w1k+rrpy9oITcbiGf3q2lrpVntv7OE8epQWUXyd2f4V5X mkuA== X-Gm-Message-State: ANhLgQ1ZjFQUQ++MjPYYW+DOcy0DQa7OkaSp26SwCXdRo8pnK8Ecsl0h 0B8mM2NQKHniX/vP8rPDhIlBVhAczqc= X-Google-Smtp-Source: ADFU+vtgNRTbQtwuKhfc/c1YvnaaEWydf8K4qxtU62lm/oERdWfqFTnroNhT1pdimLvS+h4VDiO6ww== X-Received: by 2002:a6b:d117:: with SMTP id l23mr3412035iob.217.1583352882487; Wed, 04 Mar 2020 12:14:42 -0800 (PST) Received: from [192.168.1.159] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id t28sm5912856ill.19.2020.03.04.12.14.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Mar 2020 12:14:42 -0800 (PST) Subject: Re: [PATCHSET v2 0/6] Support selectable file descriptors To: Josh Triplett Cc: io-uring@vger.kernel.org, jlayton@kernel.org References: <20200304180016.28212-1-axboe@kernel.dk> <20200304190341.GB16251@localhost> <121d15a7-4b21-368c-e805-a0660b1c851a@kernel.dk> <20200304195642.GB16527@localhost> <20200304200934.GC16527@localhost> From: Jens Axboe Message-ID: Date: Wed, 4 Mar 2020 13:14:40 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200304200934.GC16527@localhost> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 3/4/20 1:09 PM, Josh Triplett wrote: > On Wed, Mar 04, 2020 at 01:00:05PM -0700, Jens Axboe wrote: >> On 3/4/20 12:56 PM, Josh Triplett wrote: >>> On Wed, Mar 04, 2020 at 12:10:08PM -0700, Jens Axboe wrote: >>>> On 3/4/20 12:03 PM, Josh Triplett wrote: >>>>> On Wed, Mar 04, 2020 at 11:00:10AM -0700, Jens Axboe wrote: >>>>>> One of the fabled features with chains has long been the desire to >>>>>> support things like: >>>>>> >>>>>> >>>>>> >>>>>> in a single chain. This currently doesn't work, since the read/close >>>>>> depends on what file descriptor we get on open. >>>>>> >>>>>> The original attempt at solving this provided a means to pass >>>>>> descriptors between chains in a link, this version takes a different >>>>>> route. Based on Josh's support for O_SPECIFIC_FD, we can instead control >>>>>> what fd value we're going to get out of open (or accept). With that in >>>>>> place, we don't need to do any magic to make this work. The above chain >>>>>> then becomes: >>>>>> >>>>>> >>>>>> >>>>>> which is a lot more useful, and allows any sort of weird chains without >>>>>> needing to nest "last open" file descriptors. >>>>>> >>>>>> Updated the test program to use this approach: >>>>>> >>>>>> https://git.kernel.dk/cgit/liburing/plain/test/orc.c?h=fd-select >>>>>> >>>>>> which forces the use of fd==89 for the open, and then uses that for the >>>>>> read and close. >>>>>> >>>>>> Outside of this adaptation, fixed a few bugs and cleaned things up. >>>>> >>>>> I posted one comment about an issue in patch 6. >>>>> >>>>> Patches 2-5 look great; for those: >>>>> Reviewed-by: Josh Triplett >>>>> >>>>> Thanks for picking this up and running with it! >>>> >>>> Thanks for doing the prep work! I think it turned out that much better >>>> for it. >>>> >>>> Are you going to post your series for general review? I just stole >>>> your 1 patch that was needed for me. >>> >>> Since your patch series depends on mine, please feel free to run with >>> the series. Would you mind adding my patch 1 and 3 at the end of your >>> series? You need patch 1 to make this more usable for userspace, and >>> patch 3 would allow for an OP_PIPE which I'd love to have. >> >> Let me add patch 1 to the top of the stack, for the pipe part that >> probably should be taken in separately. But not a huge deal to me, >> as long as we can get it reviewed. > > That works for me; I don't mind if the pipe support goes in a bit later. > And there are many other fd-producing syscalls that need support for > userspace-selected FDs, including signalfd4, eventfd2, timerfd_create, > epoll_create1, memfd_create, userfaultfd, and the pidfd family. Right, at least on the io_uring front, adding IORING_OP_SOCKET and providing support for SOCK_SPECIFIC_FD through that would be trivial and a few lines of change. In general, we can more easily do all that through io_uring, as we have room to shove in that extra 'fd'. I've queued up patch 1 as well. >>> Do you plan to submit this during the next merge window? >> >> Maybe? In terms of timing, I think we're well within the opportunity >> to do so, at least. > > I look forward to seeing it go in. Me too :-) -- Jens Axboe