[PATCH v6 18/18] drm/virtio: add fence sanity check

[Gerd Hoffmann]

Make sure we don't leak half-initialized fences outside the driver.

Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
 drivers/gpu/drm/virtio/virtgpu_fence.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index 70d6c4329778..98358ff9996c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -41,6 +41,10 @@ bool virtio_fence_signaled(struct dma_fence *f)
 {
 	struct virtio_gpu_fence *fence = to_virtio_fence(f);
 
+	if (WARN_ON_ONCE(fence->f.seqno == 0))
+		/* leaked fence outside driver before completing
+		 * initialization with virtio_gpu_fence_emit */
+		return false;
 	if (atomic64_read(&fence->drv->last_seq) >= fence->f.seqno)
 		return true;
 	return false;
-- 
2.18.1