test-thread-pool: be more reliable

There is a rare race between the atomic_cmpxchg and
bdrv_aio_cancel/bdrv_aio_cancel_async invocations.  Detect it, the
only sensible we can do about it is to exit long_cb immediately.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed