From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 52001 invoked by alias); 14 Mar 2015 15:51:03 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 51988 invoked by uid 89); 14 Mar 2015 15:51:02 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Sat, 14 Mar 2015 15:51:01 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t2EFowPb021193 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Sat, 14 Mar 2015 11:50:59 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t2EFov8t031408; Sat, 14 Mar 2015 11:50:58 -0400 Message-ID: <550458E0.10206@redhat.com> Date: Sat, 14 Mar 2015 15:51:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Eli Zaretskii CC: gdb@sourceware.org Subject: Re: Inadvertently run inferior threads References: <83h9tq3zu3.fsf@gnu.org> <55043A63.6020103@redhat.com> <8361a339xd.fsf@gnu.org> <5504555C.804@redhat.com> In-Reply-To: <5504555C.804@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-03/txt/msg00034.txt.bz2 On 03/14/2015 03:35 PM, Pedro Alves wrote: > On 03/14/2015 02:55 PM, Eli Zaretskii wrote: >>> Date: Sat, 14 Mar 2015 13:40:51 +0000 >>> From: Pedro Alves >>> >>>> Once this happens, the debugging session seems to be ruined: the only >>>> thing I can do is kill the inferior and quit the debugger. Because >>>> there doesn't seem to be any way of stopping the threads again, not on >>>> Windows anyway. >>> >>> The threads are probably stopped, and GDB managed to get out of >>> sync somehow. >> >> In that case, the cause of it getting out of sync is the new thread >> that was started (probably by Windows)? > > Calling a function that ends up starting new threads should > work OK, but indeed that seems to be broken... > > On GNU/Linux, and a trivial program with: > > ~~~ > void > start_thread (void) > { > pthread_t thread; > > pthread_create (&thread, NULL, thread_function, NULL); > } > ~~~ > > results in: > > (gdb) p start_thread () > [New Thread 0x7ffff7fc1700 (LWP 9903)] > $1 = void > (gdb) info threads > Id Target Id Frame > 2 Thread 0x7ffff7fc1700 (LWP 9903) "start-thread-in" (running) > * 1 Thread 0x7ffff7fc2740 (LWP 9899) "start-thread-in" main () at start-thread-infcall.c:35 > I see what's going on here: #1 - we suppress the *stopped -> *running transitions/notification when doing an inferior function call (the in_infcall checks in infrun.c). #2 - new threads are spawned and given *running state, because well, they're running. #3 - we suppress the running -> *stopped transition when doing an infcall, like in #1. (The in_infcall check in normal_stop). #4 - result: _new_ threads end up in "running" state, even though they are stopped. I don't know off hand what the best fix is. I think this bug must be in the tree for a while. Curious that we don't have a test that exercises this... I can't explain why you see _all_ threads as running instead of only the new ones, though. Thanks, Pedro Alves