From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 126940 invoked by alias); 13 Jun 2018 12:10:46 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 126931 invoked by uid 89); 13 Jun 2018 12:10:46 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.8 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=whoops X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 13 Jun 2018 12:10:44 +0000 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6129C81A6FAF; Wed, 13 Jun 2018 12:10:43 +0000 (UTC) Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id AAB9A10FD2A5; Wed, 13 Jun 2018 12:10:42 +0000 (UTC) Subject: Re: [gdb/testsuite] Fix hang in fork-running-state.c To: Tom de Vries , gdb-patches@sourceware.org References: <20180612155134.7fninj4us5lq4hfc@localhost.localdomain> From: Pedro Alves Message-ID: <21cb1f1d-fad1-e9c5-a106-b0b67a1f7a50@redhat.com> Date: Wed, 13 Jun 2018 12:10:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180612155134.7fninj4us5lq4hfc@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-06/txt/msg00328.txt.bz2 On 06/12/2018 04:51 PM, Tom de Vries wrote: > ... > So, AFAIU, the hanging process is the child process that gdb detaches from. > > There's an alarm set in main before the fork, but alarms are not preserved in > the fork child: > ... > $ man alarm > ... > NOTES > Alarms created by alarm() are preserved across execve(2) and are not inherited by children created via fork(2). Whoops. > ... > So, AFAIU, once the parent is killed, there's no alarm to terminate the child. Indeed. Your patch is definitely a good idea. Please push. However, I think that still leaves an unnecessary delay until the detached child/parent terminate. They used to exit themselves, but that caused a race, so they no longer do, see here: https://sourceware.org/ml/gdb-patches/2018-03/msg00588.html Sounds like the best would be to restore the self-killing, but make it controlled by a variable that gdb sets, depending on whether gdb is staying attached to the child/parent. Thanks, Pedro Alves