drm/qxl: use iterator instead of dma_resv_shared_list

I'm not sure why it is useful to know the number of fences
in the reservation object, but we try to avoid exposing the
dma_resv_shared_list() function.

So use the iterator instead. If more information is desired
we could use dma_resv_describe() as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211129120659.1815-5-christian.koenig@amd.com

drivers/gpu/drm/qxl/qxl_debugfs.c

@@ -57,13 +57,16 @@ qxl_debugfs_buffers_info(struct seq_file *m, void *data)
 	struct qxl_bo *bo;
 
 	list_for_each_entry(bo, &qdev->gem.objects, list) {
-		struct dma_resv_list *fobj;
-		int rel;
+		struct dma_resv_iter cursor;
+		struct dma_fence *fence;
+		int rel = 0;
 
-		rcu_read_lock();
-		fobj = dma_resv_shared_list(bo->tbo.base.resv);
-		rel = fobj ? fobj->shared_count : 0;
-		rcu_read_unlock();
+		dma_resv_iter_begin(&cursor, bo->tbo.base.resv, true);
+		dma_resv_for_each_fence_unlocked(&cursor, fence) {
+			if (dma_resv_iter_is_restarted(&cursor))
+				rel = 0;
+			++rel;
+		}
 
 		seq_printf(m, "size %ld, pc %d, num releases %d\n",
 			   (unsigned long)bo->tbo.base.size,