From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 122750 invoked by alias); 15 Jun 2015 17:56:37 -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 122675 invoked by uid 89); 15 Jun 2015 17:56:36 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.6 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=no 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; Mon, 15 Jun 2015 17:56:33 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 8B995B812D; Mon, 15 Jun 2015 17:56:32 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t5FHuUX2021088; Mon, 15 Jun 2015 13:56:31 -0400 Message-ID: <557F11CE.907@redhat.com> Date: Mon, 15 Jun 2015 17:56:00 -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> <550458E0.10206@redhat.com> <83y4jrsgui.fsf@gnu.org> <557ECCA5.7050506@redhat.com> <83vbepngxm.fsf@gnu.org> <557EEF0E.1040400@redhat.com> <83ioaoopkh.fsf@gnu.org> In-Reply-To: <83ioaoopkh.fsf@gnu.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-06/txt/msg00033.txt.bz2 On 06/15/2015 06:21 PM, Eli Zaretskii wrote: >> Date: Mon, 15 Jun 2015 16:28:14 +0100 >> From: Pedro Alves >> CC: gdb@sourceware.org >> >>>> So that should mean that even for GNU/Linux, it should be possible >>>> to end in the exact same, when any thread other than the one that we >>>> had started the infcall in reports an event that doesn't cause a stop. >>>> E.g., a thread specific breakpoint, a "handle nostop" signal, etc. >>> >>> Does that involve minus_one_ptid on GNU/Linux as well? If not, that >>> call will not mark all threads as running, will it? >> >> It does. user_visible_resume_ptid returns the same irrespective >> of target_can_async. > > Then how come your test program ended up showing just that additional > thread running? You even said you couldn't explain why I saw all my > threads running on Windows. Because linux-nat.c does not report any event to infrun when a thread is created, it just immediately goes back to waiting, unlike windows-nat.c, which reports TARGET_WAITKIND_SPURIOUS. By previous test program did not have the new thread trip on any event after its creation. That's why I said: ~~~ So that should mean that even for GNU/Linux, it should be possible to end in the exact same, when any thread other than the one that we had started the infcall in reports an event that doesn't cause a stop. E.g., a thread specific breakpoint, a "handle nostop" signal, etc. ~~~ And I just confirmed it, with a thread-specific breakpoint that trips on the wrong thread, thus, reporting a trap to the core, which does not cause a user-visible stop, and then ends up marking all threads running when we gdb internally re-resumes the program. Like so: ~~~ #include #include #include #include volatile int count; static int foo (void) { usleep (1); } static void * thread_function (void *arg) { pthread_t thread; printf ("created thread %d\n", count++); while (1) { foo (); } } void new_thread (void) { pthread_t thread; pthread_create (&thread, NULL, thread_function, NULL); } int main (int argc, char **argv) { while (1) { usleep (1); } } ~~~ ~~~ (gdb) start ... Temporary breakpoint 1, main (argc=1, argv=0x7fffffffd858) at threads_infcall.c:39 39 usleep (1); (gdb) b foo thread 1 Breakpoint 2 at 0x4006a4: file threads_infcall.c, line 11. (gdb) p new_thread () [New Thread 0x7ffff7fc1700 (LWP 4928)] created thread 1 $1 = void (gdb) info threads Id Target Id Frame 2 Thread 0x7ffff7fc1700 (LWP 4928) "threads_infcall" (running) * 1 Thread 0x7ffff7fc2740 (LWP 4924) "threads_infcall" main (argc=1, argv=0x7fffffffd858) at threads_infcall.c:39 (gdb) p new_thread () [New Thread 0x7ffff77c0700 (LWP 4929)] created thread 2 $2 = void (gdb) info threads Id Target Id Frame 3 Thread 0x7ffff77c0700 (LWP 4929) "threads_infcall" (running) 2 Thread 0x7ffff7fc1700 (LWP 4928) "threads_infcall" (running) * 1 Thread 0x7ffff7fc2740 (LWP 4924) "threads_infcall" (running) (gdb) ~~~ Thanks, Pedro Alves