Userspace might poll a syncobj with the query ioctl. Call
dma_fence_enable_sw_signaling to ensure dma_fence_is_signaled returns
true in finite time.
---
panvk hits this issue when timeline semaphore is enabled. It uses the
transfer ioctl to propagate fences. dma_fence_unwrap_merge converts the
dma_fence_chain to a dma_fence_array. dma_fence_array_signaled never
return true unless signaling is enabled.
---
drivers/gpu/drm/drm_syncobj.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 4fcfc0b9b386c..58c5593c897a2 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1689,6 +1689,9 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
DRM_SYNCOBJ_QUERY_FLAGS_LAST_SUBMITTED) {
point = fence->seqno;
} else {
+ /* ensure forward progress */
+ dma_fence_enable_sw_signaling(fence);
+
dma_fence_chain_for_each(iter, fence) {
if (iter->context != fence->context) {
dma_fence_put(iter);
--
2.47.0.rc1.288.g06298d1525-goog
