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=-5.3 required=3.0 tests=BAYES_00, 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 6261AC4338F for ; Mon, 2 Aug 2021 15:23:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49037610FC for ; Mon, 2 Aug 2021 15:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235070AbhHBPXp (ORCPT ); Mon, 2 Aug 2021 11:23:45 -0400 Received: from siwi.pair.com ([209.68.5.199]:20995 "EHLO siwi.pair.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235068AbhHBPXp (ORCPT ); Mon, 2 Aug 2021 11:23:45 -0400 Received: from siwi.pair.com (localhost [127.0.0.1]) by siwi.pair.com (Postfix) with ESMTP id 3F8EE3F40E4; Mon, 2 Aug 2021 11:23:34 -0400 (EDT) Received: from SME-RED-HCI8.sme.test.net (162-238-212-202.lightspeed.rlghnc.sbcglobal.net [162.238.212.202]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by siwi.pair.com (Postfix) with ESMTPSA id 14E8B3F404F; Mon, 2 Aug 2021 11:23:34 -0400 (EDT) Subject: Re: [PATCH v6 2/2] tr2: log parent process name To: =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= , Emily Shaffer Cc: git@vger.kernel.org References: <20210722012707.205776-1-emilyshaffer@google.com> <20210722012707.205776-3-emilyshaffer@google.com> <87o8agp29o.fsf@evledraar.gmail.com> From: Jeff Hostetler Message-ID: <48a62d5e-28e2-7103-a5bb-5db7e197a4b9@jeffhostetler.com> Date: Mon, 2 Aug 2021 11:23:33 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87o8agp29o.fsf@evledraar.gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On 8/2/21 6:22 AM, Ævar Arnfjörð Bjarmason wrote: ... > > If anything the existing Windows version seems a bit unweildy, having to > apparently deal with cycles etc., I don't think that happens under > procfs, but maybe I'm missing some special-case. > It's been a while since I did the parent lookup on Windows, but... Yes, on Windows we observed cases where a PID would be recycled and a child process could have the same PID as an ancient ancestor that had long since exited. I don't think the cycle problem exists on Unix because IIRC a child process' parent-PID is set to Init when the parent exits. Windows does not update the child's parent-PID when the parent exits, so if a recently-used PID is given to one of our child processes, we can get a loop. Jeff