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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 08E37C43381 for ; Wed, 20 Mar 2019 19:19:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D50F121841 for ; Wed, 20 Mar 2019 19:19:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="QmPJbJMB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726809AbfCTTTi (ORCPT ); Wed, 20 Mar 2019 15:19:38 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:46998 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726295AbfCTTTi (ORCPT ); Wed, 20 Mar 2019 15:19:38 -0400 Received: by mail-qt1-f196.google.com with SMTP id z17so2875887qts.13 for ; Wed, 20 Mar 2019 12:19:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=5mMC0KQfG735C164EcTD+oEbBbnx3mNbSvIp42P1/ag=; b=QmPJbJMB9wKLf1bmnt3tiF7HqCc3zU327h3UXi5c8JGotzjL+VOVDTOEXl3wAoaEIu 9lAq+U7AMe3JsNkD/QoqLqLNVTcrH/nV+0YJxKHOpRootWoI8oATCWHjdDIFomwmlko/ uW0bKGgZvqQgDsmQl8QAYmYpsrgerWnYApdp8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=5mMC0KQfG735C164EcTD+oEbBbnx3mNbSvIp42P1/ag=; b=l1750zSrWsSzM71GwJ8Z9fgcVd6PavMxXt5Io5ZfFctCe9COJlpPawLdlmJN1zjANC tzL2oXfGgrQ8e4/mnO24v45MclZmOmdbOgtAOHPrpBKVSXdWXUS/86ZecReCSafX/5Mj PFtN23OSQGQYHwdfbixSi0aIT0VpeOcyv0zqmBS66zFDDThr54svX0PSQKRD8ufGoA4P 8mXtFnCnnJQbIv3diYDrVFAiKKCVE4azVPIl4KjSltZBMubLY/2CycSNUI2Nr+aNwRdm a+0b0Zn8I4i/wyktfqGWys+2ZSLTWibkhA6prlHAVKDIHH/knnM7l6WPHgfnUYoKFFCU O+hQ== X-Gm-Message-State: APjAAAWtiZn4lxQolQYKVz/9vhTWYFRpwmQ2PhgX+rHQp6aGGnHF6Q2r wJJD4AHPWPBpSfYDNU+SbaesyA== X-Google-Smtp-Source: APXvYqyCvIcP3+DKbe38H1Wq95MgCtycxVep/aavFfInOZgeS5CjRORRXHM97tnnLgFhx5cd9IBy/A== X-Received: by 2002:ac8:3a63:: with SMTP id w90mr7586860qte.233.1553109577350; Wed, 20 Mar 2019 12:19:37 -0700 (PDT) Received: from localhost ([2620:0:1004:1100:cca9:fccc:8667:9bdc]) by smtp.gmail.com with ESMTPSA id 33sm1829081qtm.28.2019.03.20.12.19.35 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Mar 2019 12:19:36 -0700 (PDT) Date: Wed, 20 Mar 2019 15:19:35 -0400 From: Joel Fernandes To: Christian Brauner Cc: Daniel Colascione , Suren Baghdasaryan , Steven Rostedt , Sultan Alsawaf , Tim Murray , Michal Hocko , Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Ingo Molnar , Peter Zijlstra , LKML , "open list:ANDROID DRIVERS" , linux-mm , kernel-team , Oleg Nesterov , Andy Lutomirski , "Serge E. Hallyn" , Kees Cook Subject: Re: pidfd design Message-ID: <20190320191935.GB76715@google.com> References: <20190319231020.tdcttojlbmx57gke@brauner.io> <20190320015249.GC129907@google.com> <20190320035953.mnhax3vd47ya4zzm@brauner.io> <4A06C5BB-9171-4E70-BE31-9574B4083A9F@joelfernandes.org> <20190320182649.spryp5uaeiaxijum@brauner.io> <20190320185156.7bq775vvtsxqlzfn@brauner.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190320185156.7bq775vvtsxqlzfn@brauner.io> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 20, 2019 at 07:51:57PM +0100, Christian Brauner wrote: [snip] > > > translate_pid() should just return you a pidfd. Having it return a pidfd > > > and a status fd feels like stuffing too much functionality in there. If > > > you're fine with it I'll finish prototyping what I had in mind. As I > > > said in previous mails I'm already working on this. > > > > translate_pid also needs to *accept* pidfds, at least optionally. > > Unless you have a function from pidfd to pidfd, you race. > > You're misunderstanding. Again, I said in my previous mails it should > accept pidfds optionally as arguments, yes. But I don't want it to > return the status fds that you previously wanted pidfd_wait() to return. > I really want to see Joel's pidfd_wait() patchset and have more people > review the actual code. No problem, pidfd_wait is also fine with me and we can change it later to translate_pid or something else if needed. Agreed that lets get to some code writing now that (I hope) we are all on the same page and discuss on actual code. - Joel