nouveau: make nouveau importing global buffers completely thread-safe, with tests

While I've closed off most races in a previous patch, a small race still existed
where importing then unreffing cound cause an invalid bo. Add a test for this case.

Racing sequence fixed:

- thread 1 releases bo, refcount drops to zero, blocks on acquiring nvdev->lock.
- thread 2 increases refcount to 1.
- thread 2 decreases refcount to zero, blocks on acquiring nvdev->lock.

At this point the 2 threads will clean up the same bo.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@ubuntu.com>
Reviewed-By: Emil Velikov <emil.l.velikov@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/nouveau/.gitignore b/tests/nouveau/.gitignore
new file mode 100644
index 00000000..837bfb91
--- /dev/null
+++ b/tests/nouveau/.gitignore
@@ -0,0 +1 @@
+threaded