From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.devel Subject: Re: scratch/sigchld-fd 8f0ce42 1/2: Fix deadlock when receiving SIGCHLD during 'pselect'. Date: Wed, 20 Jan 2021 09:37:31 +0100 Message-ID: <87pn20vwac.fsf@igel.home> References: <20210116184947.2105.45267@vcs0.savannah.gnu.org> <20210116184949.3C17C211A5@vcs0.savannah.gnu.org> <834kjd7yk5.fsf@gnu.org> <83turc7n93.fsf@gnu.org> <871regr6x5.fsf@igel.home> <83r1mg6zy2.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="11672"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1.90 (gnu/linux) Cc: phst@google.com, p.stephani2@gmail.com, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Jan 20 09:38:39 2021 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l290f-0002su-Cw for ged-emacs-devel@m.gmane-mx.org; Wed, 20 Jan 2021 09:38:37 +0100 Original-Received: from localhost ([::1]:49388 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l290e-0004zo-EU for ged-emacs-devel@m.gmane-mx.org; Wed, 20 Jan 2021 03:38:36 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:38318) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l28zj-0004ao-Ep for emacs-devel@gnu.org; Wed, 20 Jan 2021 03:37:39 -0500 Original-Received: from mail-out.m-online.net ([212.18.0.9]:36141) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l28zg-0003JB-Ey; Wed, 20 Jan 2021 03:37:39 -0500 Original-Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4DLJms0lnmz1qs3l; Wed, 20 Jan 2021 09:37:33 +0100 (CET) Original-Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4DLJms0R8Jz1qqkp; Wed, 20 Jan 2021 09:37:33 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Original-Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id uqBWEnpqg2ap; Wed, 20 Jan 2021 09:37:32 +0100 (CET) X-Auth-Info: 74/2ubi/98EqpPV5YBHnxM6njZsQE4ukmFN7aEB5A9uIyXy06E+efM+G4eiFi5Gi Original-Received: from igel.home (ppp-46-244-163-184.dynamic.mnet-online.de [46.244.163.184]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Wed, 20 Jan 2021 09:37:32 +0100 (CET) Original-Received: by igel.home (Postfix, from userid 1000) id D9FB62C324D; Wed, 20 Jan 2021 09:37:31 +0100 (CET) X-Yow: .. ich bin in einem dusenjet ins jahr 53 vor chr... ich lande im antiken Rom... einige gladiatoren spielen scrabble... ich rieche PIZZA... In-Reply-To: <83r1mg6zy2.fsf@gnu.org> (Eli Zaretskii's message of "Wed, 20 Jan 2021 05:37:41 +0200") Received-SPF: pass client-ip=212.18.0.9; envelope-from=whitebox@nefkom.net; helo=mail-out.m-online.net X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.248, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:263197 Archived-At: On Jan 20 2021, Eli Zaretskii wrote: > AFAIU, this is an issue for programs that install a SIGCHLD handler > immediately before calling pselect. But Emacs has a SIGCHLD handler > installed at all times, so if the signal hits outside of the pselect > call, we should be able to detect that reliably. No, the race between checking for the signal and entering pselect still exists. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."