It's not allowed to nest another dma_fence container into a dma_fence_array
or otherwise we can run into recursion.
Warn about that when we create a dma_fence_array.
v2: fix comment style and typo in the warning pointed out by Thomas
Signed-off-by: Christian König <christian.koe...@amd.com>
Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>
---
drivers/dma-buf/dma-fence-array.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/dma-buf/dma-fence-array.c
b/drivers/dma-buf/dma-fence-array.c
index 3e07f961e2f3..cb1bacb5a42b 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -176,6 +176,20 @@ struct dma_fence_array *dma_fence_array_create(int
num_fences,
array->base.error = PENDING_ERROR;
+ /*
+ * dma_fence_array objects should never contain any other fence
+ * containers or otherwise we run into recursion and potential kernel
+ * stack overflow on operations on the dma_fence_array.
+ *
+ * The correct way of handling this is to flatten out the array by the
+ * caller instead.
+ *
+ * Enforce this here by checking that we don't create a dma_fence_array
+ * with any container inside.
+ */
+ while (num_fences--)
+ WARN_ON(dma_fence_is_container(fences[num_fences]));
+
return array;
}
EXPORT_SYMBOL(dma_fence_array_create);
--
2.25.1
