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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 9351AC282CE for ; Wed, 24 Apr 2019 09:05:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E0BC21773 for ; Wed, 24 Apr 2019 09:05:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727754AbfDXJFC (ORCPT ); Wed, 24 Apr 2019 05:05:02 -0400 Received: from mout.kundenserver.de ([212.227.126.130]:51105 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726353AbfDXJFC (ORCPT ); Wed, 24 Apr 2019 05:05:02 -0400 Received: from [192.168.1.115] ([95.114.95.254]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.167]) with ESMTPSA (Nemesis) id 1MBDWo-1hVq3z15Cw-00CgRI; Wed, 24 Apr 2019 11:03:45 +0200 Subject: Re: [PATCH RFC 1/2] Add polling support to pidfd To: Daniel Colascione , Christian Brauner Cc: Joel Fernandes , Jann Horn , Oleg Nesterov , Florian Weimer , kernel list , Andy Lutomirski , Steven Rostedt , Suren Baghdasaryan , Linus Torvalds , Alexey Dobriyan , Al Viro , Andrei Vagin , Andrew Morton , Arnd Bergmann , "Eric W. Biederman" , Kees Cook , linux-fsdevel , "open list:KERNEL SELFTEST FRAMEWORK" , Michal Hocko , Nadav Amit , Serge Hallyn , Shuah Khan , Stephen Rothwell , Taehee Yoo , Tejun Heo , Thomas Gleixner , kernel-team , Tycho Andersen References: <20190411175043.31207-1-joel@joelfernandes.org> <20190416120430.GA15437@redhat.com> <20190416192051.GA184889@google.com> <20190417130940.GC32622@redhat.com> <20190419190247.GB251571@google.com> <20190419191858.iwcvqm6fihbkaata@brauner.io> <20190419194902.GE251571@google.com> From: "Enrico Weigelt, metux IT consult" Organization: metux IT consult Message-ID: <11c00eba-f078-9a67-97e6-bd5a74f3acaa@metux.net> Date: Wed, 24 Apr 2019 11:03:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:KC8hpxEUkKPdQ5bUC8dOti8jq7M1rTgdpgBOhcD4aTWX9/TIleV XVyUHKf7VLY23NikE3fVZpxZXZX0Hqf1aI3bAfdntsdA6fuCkKYfaicCHWf3YWbu47SJoFm CNjzCIXRSgGzW5hAf/wDzI7Hxtlfxe5V7Ak/3vcHixeqOmY7YFw7ucpn881rwP9eyMg0tuj 9oI6kwbTbypsO/EgRbC7w== X-UI-Out-Filterresults: notjunk:1;V03:K0:m9/e0FynbXE=:5kp9gxBK/CMIeyCEkpGa1Y 11ot8a/HRUWkhvmId1F9mHXleHg5pIv2UdL6GIFgSbqgEvCV5kBYVIPyTei3lea9kg9WYn3jy OBVs9Oh54E42oigFxQ/HrItOk3tPGxYcEDTOOlrGD4INswxlrSCEP/bRUiJsSxmUkAbaTbO5/ rk11ycM8JI+w0+cnBgrJf6RxS/FmO/uwOwpmdwiu23gXQ7SgCPhGOxSJNOI2XJj6hjhX8nncJ kJvZ2Irk1sXLBcHVFYYuCPQMdJXTgBSG1qZCXQvZpdOV48y+RrAJlnmJenHTrXG0me0DmPOBA qZKQWZj1qyqc85FvIJ6mlbpeVME/AvYtD0SkSRcbKKZaiGN/AWIXAn8w7tQ/H2P4Ay8mUmZ10 Pg3nUZjX3xk2vCbeOh+IAC10QyiAnfuJ0zOl0BqXtf4nef1uJy9g55I7DZ4uNH14wGAiU0Yhv AKhMXV61RHuUgx5XumPJbhozkddH9GLBmd0SBvUxqvSHn9EcIxREmkSs7ztxIhhIe5mJ7bMU9 A+NsHzFWet2UuDluMOQfTHategchxBy+ZBnbJ23d3kmMVSyNcMi218kipFzpbsBpI3Ncc4Gf6 B78G2RCOEHJL/L5LNqKldvCXn5xtiBKN456jteC2MIrEVYvdQQdhZvV35vwZGrHEC1oyzn3M/ g2sUWXwjNbS15x7feCtQGVQxmuHhWYVFt7usz0W9J307rMxtxaQ+p4I1+A1udpI2VMiZt+Gvv kRSi46BOpRHolU5Ilv+DgfzqGzUvRsUCBZw0BzhBB2v7+JAapez2lbC1nYE= Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 20.04.19 01:46, Daniel Colascione wrote: > If you turn pidfd into an event stream, reads have to be destructive. > If reads are destructive, you can't share pidfds instances between > multiple readers. Can't we find a way to duplicate them ? Someting like dup(), but with actually duplicating the open file ? (maybe add a flag for that to dup3 ?) --mtx -- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287