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=-4.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 4D94BC48BE6 for ; Wed, 16 Jun 2021 14:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 254B961241 for ; Wed, 16 Jun 2021 14:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233697AbhFPOET (ORCPT ); Wed, 16 Jun 2021 10:04:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233674AbhFPOES (ORCPT ); Wed, 16 Jun 2021 10:04:18 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3751C061574; Wed, 16 Jun 2021 07:02:11 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id l7-20020a05600c1d07b02901b0e2ebd6deso1785260wms.1; Wed, 16 Jun 2021 07:02:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:references:from:subject:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=oxY0GQVk3+mhuNFcdWASnvkCwJYL3XKMxNNz6CvkGVE=; b=ucFe8uEGrCRlTEyxb9M7BOPpht4bV7diI9wCcf6+UBEBNFLxPgTcuISfTzyYVpW4OL 8XvFLGafSMSxc1P5bt/ddLuMeQKE3HLJvLOB4OnZOTQzz9Z9sKn8JeX8D4IV8duB2ULJ 8Z5cDkU88eO7uu/AZK7E1Nh/lu4o30xVxU/qhFMxcrH1WmW2gT8RuatrhtxqsX77MtR/ IP8hIcNcIdEmz0zFxtrd+yUPFEX3iYkD1krLj5RsSq2cZJyYiQ7KxkgFStXE0p9L4r1y 290FsoCA4qlNbdiVsaUBInLDgbaFTlD4cL3LeeXYWE/0rsaKmXhYbD6Jz7dpkQlhnnZO WX0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=oxY0GQVk3+mhuNFcdWASnvkCwJYL3XKMxNNz6CvkGVE=; b=doXPccjxIX2QapbuycvD1arUZpYD80ufwJ+sG8PwDXJFkMbDIOkneeETvEuqdHgqBg bcbU8We3ViC/qr5wEHrZv9cv2fQv+oI8spNKZnXN0uNlfSfrd+vnhebidMbbfB9/n80u ayCdEOEJgwYTdOPyVEXcEZ1VYltyv12CaPk+f09EL3h7C6NXOXAb+nhDMiVsUpqZontd IO08X+ItFN6LwsmMhp/fvRyW2gNNau/g6xRVvekpvp0OfrvhNswKcqRmtMesdx3acO9b OVHq51Jr/uygLH6APKTwR7GU9WkIZBVUnDcaIJfGvtC0hljCqDFosTNqRL9SZDszAJzK 5GSQ== X-Gm-Message-State: AOAM530RLzLMgJDYB+aicibwqJNCf70pcYjA+MGVvdWD8I7nS0o+wc76 UQ+bNW1YLE/WXrt43LPJOVqb/2TvSLh4PQ== X-Google-Smtp-Source: ABdhPJydSNfzdRcG+xi6F8zzi6+B7T+flbgvOPaf9jf3Lx/N6e4wwtQ5YnzDHXKK7yHzqEZuQnjnXQ== X-Received: by 2002:a1c:f60f:: with SMTP id w15mr11531818wmc.5.1623852130112; Wed, 16 Jun 2021 07:02:10 -0700 (PDT) Received: from [192.168.8.197] ([148.252.128.74]) by smtp.gmail.com with ESMTPSA id q19sm5010731wmf.22.2021.06.16.07.02.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Jun 2021 07:02:09 -0700 (PDT) To: Olivier Langlois , Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <60c83c12.1c69fb81.e3bea.0806SMTPIN_ADDED_MISSING@mx.google.com> <93256513-08d8-5b15-aa98-c1e83af60b54@gmail.com> <4f32f06306eac4dd7780ed28c06815e3d15b43ad.camel@trillion01.com> From: Pavel Begunkov Subject: Re: [PATCH] io_uring: store back buffer in case of failure Message-ID: Date: Wed, 16 Jun 2021 15:01:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <4f32f06306eac4dd7780ed28c06815e3d15b43ad.camel@trillion01.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 6/16/21 2:42 PM, Olivier Langlois wrote: > On Tue, 2021-06-15 at 15:51 -0600, Jens Axboe wrote: >> Ditto for this one, don't see it in my email nor on the list. >> > I can resend you a private copy of this one but as Pavel pointed out, > it contains fatal flaws. > > So unless someone can tell me that the idea is interesting and has > potential and can give me some a hint or 2 about how to address the > challenges to fix the current flaws, it is pretty much a show stopper > to me and I think that I am going to let it go... It'd need to go through some other context, e.g. task context. task_work_add() + custom handler would work, either buf-select synchronisation can be reworked, but both would rather be bulky and not great. I'm more curious if we ever hit REQ_F_BUFFER_SELECTED branch in io_clean_op(), because it would just drop the id on the floor... It might use a WARN_ONCE. -- Pavel Begunkov