[PATCH v2] drm/syncobj: ensure progress for syncobj queries

[Chia-I Wu <olvaffe@xxxxxxxxx>]

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.

Fixes: 27b575a9aa2f ("drm/syncobj: add timeline payload query ioctl v6")
Signed-off-by: Chia-I Wu <olvaffe@xxxxxxxxx>

---

v2: add Signed-off-by and Fixes tags
---
 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);
-- 
2.47.0.105.g07ac214952-goog