drm/virtio: rework virtio_fence_signaled

virtio_gpu_fence_event_process sets the last_fence_id and
subsequently calls dma_fence_signal_locked(..).

dma_fence_signal_locked(..) sets DMA_FENCE_FLAG_SIGNALED_BIT,
which is actually checked before &dma_fence_ops.(*signaled) is
called.

The check for last_fence_id is therefore a bit redundant, and
it will not be sufficient to check the last_fence_id for multiple
synchronization timelines.  Remove it.

v3: add r-b tags
Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20201201021623.619-2-gurchetansingh@chromium.orgSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_fence.c

@@ -42,14 +42,10 @@ static const char *virtio_gpu_get_timeline_name(struct dma_fence *f)
 
 static bool virtio_gpu_fence_signaled(struct dma_fence *f)
 {
-	struct virtio_gpu_fence *fence = to_virtio_gpu_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_fence_id) >= fence->f.seqno)
-		return true;
+	/* leaked fence outside driver before completing
+	 * initialization with virtio_gpu_fence_emit.
+	 */
+	WARN_ON_ONCE(f->seqno == 0);
 	return false;
 }