From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52503) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dedfM-0007Db-Gp for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:45:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dedfJ-00017b-3c for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:45:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53202) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dedfI-00015R-Qf for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:45:33 -0400 Date: Mon, 7 Aug 2017 09:45:24 +0100 From: "Daniel P. Berrange" Message-ID: <20170807084524.GF18259@redhat.com> Reply-To: "Daniel P. Berrange" References: <7c4ddf95a57f7dfa546c11f8a08a9091b8bd1ceb.1501362828.git-series.knut.omang@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <7c4ddf95a57f7dfa546c11f8a08a9091b8bd1ceb.1501362828.git-series.knut.omang@oracle.com> Subject: Re: [Qemu-devel] [PATCH v6 1/4] tests: Add test-listen - a stress test for QEMU socket listen List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Knut Omang Cc: Gerd Hoffmann , Paolo Bonzini , qemu-devel@nongnu.org On Sat, Jul 29, 2017 at 11:18:15PM +0200, Knut Omang wrote: > There's a potential race condition between multiple bind()'s > attempting to bind to the same port, which occasionally > allows more than one bind to succeed against the same port. > > When a subsequent listen() call is made with the same socket > only one will succeed. > > The current QEMU code does however not take this situation into account > and the listen will cause the code to break out and fail even > when there are actually available ports to use. > > This test exposes two subtests: > > /socket/listen-serial > /socket/listen-compete > > The "compete" subtest creates a number of threads and have them all trying to bind > to the same port with a large enough offset input to > allow all threads to get it's own port. > The "serial" subtest just does the same, except in series in a > single thread. > > The serial version passes, probably in most versions of QEMU. > > The parallel version exposes the problem in a relatively reliable way, > eg. it fails a majority of times, but not with a 100% rate, occasional > passes can be seen. Nevertheless this is quite good given that > the bug was tricky to reproduce and has been left undetected for > a while. > > The problem seems to be present in all versions of QEMU. > > The original failure scenario occurred with VNC port allocation > in a traditional Xen based build, in different code > but with similar functionality. > > Reported-by: Bhavesh Davda > Signed-off-by: Knut Omang > Reviewed-by: Yuval Shaia > Reviewed-by: Bhavesh Davda > Reviewed-by: Girish Moodalbail > --- > tests/Makefile.include | 2 +- > tests/test-listen.c | 253 ++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 255 insertions(+) > create mode 100644 tests/test-listen.c > > diff --git a/tests/Makefile.include b/tests/Makefile.include > index 7af278d..b37c0c8 100644 > --- a/tests/Makefile.include > +++ b/tests/Makefile.include > @@ -128,6 +128,7 @@ check-unit-y += tests/test-bufferiszero$(EXESUF) > gcov-files-check-bufferiszero-y = util/bufferiszero.c > check-unit-y += tests/test-uuid$(EXESUF) > check-unit-y += tests/ptimer-test$(EXESUF) > +#check-unit-y += tests/test-listen$(EXESUF) > gcov-files-ptimer-test-y = hw/core/ptimer.c > check-unit-y += tests/test-qapi-util$(EXESUF) > gcov-files-test-qapi-util-y = qapi/qapi-util.c > @@ -769,6 +770,7 @@ tests/test-arm-mptimer$(EXESUF): tests/test-arm-mptimer.o > tests/test-qapi-util$(EXESUF): tests/test-qapi-util.o $(test-util-obj-y) > tests/numa-test$(EXESUF): tests/numa-test.o > tests/vmgenid-test$(EXESUF): tests/vmgenid-test.o tests/boot-sector.o tests/acpi-utils.o > +tests/test-listen$(EXESUF): tests/test-listen.o $(test-util-obj-y) > > tests/migration/stress$(EXESUF): tests/migration/stress.o > $(call quiet-command, $(LINKPROG) -static -O3 $(PTHREAD_LIB) -o $@ $< ,"LINK","$(TARGET_DIR)$@") > diff --git a/tests/test-listen.c b/tests/test-listen.c > new file mode 100644 > index 0000000..5c07537 > --- /dev/null > +++ b/tests/test-listen.c > @@ -0,0 +1,253 @@ > +/* > + * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. > + * Author: Knut Omang > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 > + * as published by the Free Software Foundation. Can you change that to "version 2 or later" - per the LICENSE file, we don't accept contributions under "version 2 only" except for 4 specific subdirs: "As of July 2013, contributions under version 2 of the GNU General Public License (and no later version) are only accepted for the following files or directories: bsd-user/, linux-user/, hw/vfio/, hw/xen/xen_pt*." > + * > + * Test parallel port listen configuration with > + * dynamic port allocation > + */ Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|