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: Tue, 19 Jan 2021 21:46:46 +0100 Message-ID: <871regr6x5.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> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33306"; 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, Philipp Stephani , emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Jan 19 22:08:42 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 1l1yF0-0008ZM-ES for ged-emacs-devel@m.gmane-mx.org; Tue, 19 Jan 2021 22:08:42 +0100 Original-Received: from localhost ([::1]:47908 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l1yEz-0008Os-1l for ged-emacs-devel@m.gmane-mx.org; Tue, 19 Jan 2021 16:08:41 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:58306) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l1xu3-0004mB-Pd for emacs-devel@gnu.org; Tue, 19 Jan 2021 15:47:03 -0500 Original-Received: from mail-out.m-online.net ([2001:a60:0:28:0:1:25:1]:54766) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l1xtw-0002hT-EE; Tue, 19 Jan 2021 15:47:03 -0500 Original-Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4DL10m25gSz1rwZq; Tue, 19 Jan 2021 21:46:48 +0100 (CET) Original-Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4DL10m1c89z1qrQ4; Tue, 19 Jan 2021 21:46:48 +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 pZpOdj0ldnwd; Tue, 19 Jan 2021 21:46:47 +0100 (CET) X-Auth-Info: /UcfM6ehE4OAa27z1aKbzNiawJ3M0d5mGghEp0upVaZe4tGKf8RMDDyDiPdQvfjp Original-Received: from igel.home (ppp-46-244-184-249.dynamic.mnet-online.de [46.244.184.249]) (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; Tue, 19 Jan 2021 21:46:47 +0100 (CET) Original-Received: by igel.home (Postfix, from userid 1000) id 5A36F2C3257; Tue, 19 Jan 2021 21:46:46 +0100 (CET) X-Yow: I can see you GUYS an' GALS need a LOT of HELP...You're all very STUPID!! I used to be STUPID, too..before I started watching UHF-TV!! In-Reply-To: <83turc7n93.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 19 Jan 2021 21:14:16 +0200") Received-SPF: pass client-ip=2001:a60:0:28:0:1:25:1; 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, 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:263188 Archived-At: On Jan 19 2021, Eli Zaretskii wrote: > I'd be happier if we had some direct evidence to these effects. I'd > also be surprised to hear that pselect doesn't return with EINTR when > SIGCHLD comes in. It is more likely that SIGCHLD is delivered before > we call pselect, but if that is the case, we should be able to > reliably detect that, I think. If you want reliable detection of SIGCHLD, you need to block the signal around pselect and let pselect unblock it, atomically. 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."