From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conssluserg-04.nifty.com (conssluserg-04.nifty.com [210.131.2.83]) by sourceware.org (Postfix) with ESMTPS id 15C6B3858D28 for ; Mon, 18 Apr 2022 12:49:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 15C6B3858D28 Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=nifty.ne.jp Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=nifty.ne.jp Received: from Express5800-S70 (ak044095.dynamic.ppp.asahi-net.or.jp [119.150.44.95]) (authenticated) by conssluserg-04.nifty.com with ESMTP id 23ICmJPa020214; Mon, 18 Apr 2022 21:48:19 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-04.nifty.com 23ICmJPa020214 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.ne.jp; s=dec2015msa; t=1650286100; bh=nmIFEqsEILyKPeddRX9n5w1fQ2POujKDzP0B6YxHwHc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=a7rQ2OI1wOLdKSwL04s0mTXV9oGvhNPcvHstZDjyRaqkdslBjW5lszrXUAG4wGtHu Ln7YNA90/1rlRWN/trCk5rC78S16VWkRoc0bPb2ZnbR1PT2Ry0WH64o/eJwaljUbJt QSWso7h6uNV3cL6V+piafMVXnpk6pzStYTje+874UMT86lyVGpr8f2jczfwRksw+/0 LLbqrv2hFh/+gqwBkQDeFL4JcSP2kNlZxfLDsXWDOKMcs8A7m071d0Xyde2w16uAyd 4ZVXkZ22IGkpJoUHRHKea6NPY0FFXk2lcABDPe7Irbb1UkNeMdfBOi+NJDLAmrlvVv gzQqdkPQJB+9Q== X-Nifty-SrcIP: [119.150.44.95] Date: Mon, 18 Apr 2022 21:48:23 +0900 From: Takashi Yano To: cygwin@cygwin.com Cc: Alexey Izbyshev Subject: Re: Deadlock when pressing Ctrl-C at startup of a native console application Message-Id: <20220418214823.a01ed743ceb15d3708ee3fd9@nifty.ne.jp> In-Reply-To: <20220416181650.cdb31ec9c75189724bf2f498@nifty.ne.jp> References: <355a1f23bf39b0670110a840075224a2@ispras.ru> <20220416181650.cdb31ec9c75189724bf2f498@nifty.ne.jp> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.30; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Apr 2022 12:49:10 -0000 On Sat, 16 Apr 2022 18:16:50 +0900 Takashi Yano wrote: > On Fri, 15 Apr 2022 21:09:05 +0300 > Alexey Izbyshev wrote: > > Hi, > > > > I've discovered that pressing Ctrl-C in a Cygwin ssh session running the > > following command can cause a deadlock: > > > > $ while python -c ''; do :; done > > > > The exact native application doesn't matter here, e.g. "ping -n 1 > > localhost >/dev/null" instead of "python -c ''" also "works". > > > > The deadlock is most easily triggered when CPU is fully loaded. It takes > > no more than 20 tries on my machine to hit it (and when I first saw it, > > it was on the first try). > > > > When the deadlock is triggered, there are conhost.exe and > > cygwin-console-helper.exe processes, but there is no python. > > > > The exact process tree varies depending on Cygwin version. With the > > vanilla 3.3.4 (the root is bash spawned by sshd): > > > > bash---bash-+-conhost.exe > > `-cygwin-console-helper.exe > > > > With 20220301 snapshot > > (https://cygwin.com/snapshots/x86/cygwin1-20220301.dll.xz), I get one of > > the two following trees with an extra conhost.exe process: > > > > bash---bash-+-conhost.exe > > |-conhost.exe > > `-cygwin-console-helper.exe > > > > or > > > > bash---bash-+-conhost.exe > > | `-cygwin-console-helper.exe > > `-conhost.exe > > > > I was testing with 32-bit Cygwin on x64 Windows 10 21H2. > > Thanks for the report. I could reproduce the issue. > I also found the current git master does not have this issue, > while cygwin-3_3-branch does. > > Now I am identifying which patch solved the issue. > One is obviously: > https://cygwin.com/pipermail/cygwin-patches/2022q2/011870.html > however, this was applied also for cygwin-3_3-branch. Therefore, > another patch also should affect this issue. I identified the cause and applied a workaround patch. The countermeasure version is available at: https://tyan0.yr32.net/cygwin/x86/test/cygwin1-20220418.dll.xz https://tyan0.yr32.net/cygwin/x86_64/test/cygwin1-20220418.dll.xz Could you please test? -- Takashi Yano