Re: [PULL 10/15] tests/functional: fix race in virtio balloon test

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Mar 07, 2025 at 01:39:17PM +0100, Thomas Huth wrote:
> On 07/03/2025 13.34, Philippe Mathieu-Daudé wrote:
> > Hi Thomas, Daniel,
> > 
> > On 7/3/25 12:53, Thomas Huth wrote:
> > > From: Daniel P. Berrangé <berrange@redhat.com>
> > > 
> > > There are two race conditions in the recently added virtio balloon
> > > test
> > > 
> > >   * The /dev/vda device node is not ready
> > >   * The virtio-balloon driver has not issued the first stats refresh
> > > 
> > > To fix the former, monitor dmesg for a line about 'vda'.
> > > 
> > > To fix the latter, retry the stats query until seeing fresh data.
> > > 
> > > Adding 'quiet' to the kernel command line reduces serial output
> > > which otherwise slows boot, making it less likely to hit the former
> > > race too.
> > > 
> > > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > > Message-ID: <20250304183340.3749797-1-berrange@redhat.com>
> > > Reviewed-by: Thomas Huth <thuth@redhat.com>
> > > Reviewed-by: David Hildenbrand <david@redhat.com>
> > > [thuth: Break long line to avoid checkpatch error]
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >   tests/functional/test_virtio_balloon.py | 26 ++++++++++++++++++++-----
> > >   1 file changed, 21 insertions(+), 5 deletions(-)
> > 
> > This fix isn't really working, and is more of band-aid IIUC.
> > 
> > With the following patch restricting to KVM accel, do we still want it merged?
> 
> Yes, I think it still makes this test more robust.

Agreed, even though this patch isn't perfect it is definitely fixing two
clear race conditions.


With regards,
Daniel
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