On Mon, 2017-08-07 at 09:45 +0100, Daniel P. Berrange wrote: > 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 <bhavesh.da...@oracle.com> > > Signed-off-by: Knut Omang <knut.om...@oracle.com> > > Reviewed-by: Yuval Shaia <yuval.sh...@oracle.com> > > Reviewed-by: Bhavesh Davda <bhavesh.da...@oracle.com> > > Reviewed-by: Girish Moodalbail <girish.moodalb...@oracle.com> > > --- > > 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 <knut.om...@oracle.com> > > + * > > + * 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*."
Oh, sorry - I wasn't aware of this, +"...or later" is fine with me. Would you like me to send a v7 of the set with only that change, or can you amend it as part of the merge? Thanks, Knut > > > + * > > + * Test parallel port listen configuration with > > + * dynamic port allocation > > + */ > > > Regards, > Daniel
