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Call > dma_fence_enable_sw_signaling to ensure dma_fence_is_signaled returns > true in finite time. Wait a second, just querying the fence status is absolutely not guaranteed to return true in finite time. That is well documented on the dma_fence() object. When you want to poll on signaling from userspace you really need to call poll or the wait IOCTL with a zero timeout. That will also return immediately but should enable signaling while doing that. So just querying the status should absolutely *not* enable signaling. That's an intentional separation. Regards, Christian. > > Fixes: 27b575a9aa2f ("drm/syncobj: add timeline payload query ioctl v6") > Signed-off-by: Chia-I Wu > > --- > > 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);