Re: [PATCH v3 2/2] tests/9pfs: fix test dir for parallel tests

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Sonntag, 1. November 2020 18:44:44 CET Greg Kurz wrote:
> On Sun, 1 Nov 2020 15:37:12 +0100
> 
> Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
> > Use mkdtemp() to generate a unique directory for the 9p 'local' tests.
> > 
> > This fixes occasional 9p test failures when running 'make check -jN' if
> > QEMU was compiled for multiple target architectures, because the
> > individual
> > architecture's test suites would run in parallel and interfere with each
> > other's data as the test directory was previously hard coded and hence the
> > same directory was used by all of them simultaniously.
> > 
> > This also requires a change how the test directory is created and deleted:
> > As the test path is now randomized and virtio_9p_register_nodes() being
> > called in a somewhat undeterministic way, that's no longer an appropriate
> > place to create and remove the test directory. Use a constructor and
> > destructor function for creating and removing the test directory instead.
> > Unfortunately libqos currently does not support setup/teardown callbacks
> > to handle this more cleanly.
> > 
> > The constructor functions needs to be in virtio-9p-test.c, not in
> > virtio-9p.c, because in the latter location it would cause all apps that
> > link to libqos (i.e. entirely unrelated test suites) to create a 9pfs
> > test directory as well, which would even break other test suites.
> > 
> > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> > ---
> 
> Reviewed-by: Greg Kurz <groug@kaod.org>

Thanks for the overtime, on a Sunday!

Queued on 9p.next:
https://github.com/cschoenebeck/qemu/commits/9p.next

And this one with Peter Xu's patches on top, just for testing:
https://github.com/cschoenebeck/qemu/commits/9p.experimental.2

> I could run 'make check -j' with 4 archs (ppc64, x86_64, aarch64, s390x)
> on a POWER9 system with 128 cpus, for ~1 hour without seeing any failure.
> 
> Tested-by: Greg Kurz <groug@kaod.org>

OO Sounds like having advantages working for IBM. Respect. I start to get envy 
as these beasts are running towards PCIe 6, while we regular x86 users would 
already be glad having PCIe 4.

I give it some more spinning hours this time, just to be sure, before sending 
the PR tomorrow morning. But I think it's all right now.

Thanks!

Best regards,
Christian Schoenebeck