From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conssluserg-06.nifty.com (conssluserg-06.nifty.com [210.131.2.91]) by sourceware.org (Postfix) with ESMTPS id EC00C3858404 for ; Wed, 10 Nov 2021 00:37:52 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org EC00C3858404 Received: from Express5800-S70 (z221123.dynamic.ppp.asahi-net.or.jp [110.4.221.123]) (authenticated) by conssluserg-06.nifty.com with ESMTP id 1AA0bYfb014253 for ; Wed, 10 Nov 2021 09:37:34 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-06.nifty.com 1AA0bYfb014253 X-Nifty-SrcIP: [110.4.221.123] Date: Wed, 10 Nov 2021 09:37:41 +0900 From: Takashi Yano To: cygwin@cygwin.com Subject: Re: Another pipe-related problem? Message-Id: <20211110093741.d15b99a1361e680f87b61fd8@nifty.ne.jp> In-Reply-To: <20211110091613.26a636e789fe36a098412f1b@nifty.ne.jp> References: <05c4180e-396b-4af3-ac0c-2ab8125df17e@cornell.edu> <20211110082245.2943cf3c2519bff24a6843b2@nifty.ne.jp> <20211110082932.3e33bae9364db0dda0c57d16@nifty.ne.jp> <20211110084822.fa32acb567bd26ab43c393bd@nifty.ne.jp> <20211110091613.26a636e789fe36a098412f1b@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=-5.9 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 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: Wed, 10 Nov 2021 00:37:56 -0000 On Wed, 10 Nov 2021 09:16:13 +0900 Takashi Yano wrote: > On Wed, 10 Nov 2021 08:48:22 +0900 > Takashi Yano wrote: > > On Wed, 10 Nov 2021 08:29:32 +0900 > > Takashi Yano wrote: > > > On Wed, 10 Nov 2021 08:22:45 +0900 > > > Takashi Yano wrote: > > > > On Tue, 9 Nov 2021 09:11:28 -0500 > > > > Ken Brown wrote: > > > > > I'll have to reproduce the hang myself in order to test this (or maybe you could > > > > > test it), but I now have a new guess: If the read call above keeps failing with > > > > > EINTR, then we're in an infinite loop. This could happen because of the > > > > > following code in fhandler_pipe::raw_read: > > > > > > > > > > DWORD waitret = cygwait (read_mtx, timeout); > > > > > switch (waitret) > > > > > { > > > > > case WAIT_OBJECT_0: > > > > > break; > > > > > case WAIT_TIMEOUT: > > > > > set_errno (EAGAIN); > > > > > len = (size_t) -1; > > > > > return; > > > > > default: > > > > > set_errno (EINTR); > > > > > len = (size_t) -1; > > > > > return; > > > > > } > > > > > > > > > > Takashi, is EINTR really the appropriate errno in the default case? Isn't > > > > > cygwait supposed to handle signals? > > > > > > > > I assume cygwait() returns WAIT_SIGNALED when signalled > > > > by SIGINT, SIGTERM, SIGTSTP, etc... In this case, EINTR > > > > should return I think. > > > > > > > > Is it wrong? > > > > > > Ah, if SA_RESTART is set, we should continue to read even > > > if signalled... [...] > No, we don't have to do that because cygwait() do the same > internally. cygwain() returns WAIT_SIGNALED when signalled > only if SA_RESTART is not set. So, the current code LGTM. Ah, however, should we handle WAIT_CANCELED here and call pthread::static_cancel_self() as following? DWORD waitret = cygwait (read_mtx, timeout); switch (waitret) { case WAIT_OBJECT_0: break; case WAIT_TIMEOUT: set_errno (EAGAIN); len = (size_t) -1; return; WAIT_SIGNALED: set_errno (EINTR); len = (size_t) -1; return; WAIT_CANCELED: pthread::static_cancel_self (); /* NOTREACHED */ default: /* Should not reach here. */ __seterrno (); len = (slze_t) -1; return; } -- Takashi Yano