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-rw-r--r--Documentation/bpf/kfuncs.rst17
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
index 226313747be5..9a78533d25ac 100644
--- a/Documentation/bpf/kfuncs.rst
+++ b/Documentation/bpf/kfuncs.rst
@@ -100,6 +100,23 @@ Hence, whenever a constant scalar argument is accepted by a kfunc which is not a
size parameter, and the value of the constant matters for program safety, __k
suffix should be used.
+2.2.2 __uninit Annotation
+--------------------
+
+This annotation is used to indicate that the argument will be treated as
+uninitialized.
+
+An example is given below::
+
+ __bpf_kfunc int bpf_dynptr_from_skb(..., struct bpf_dynptr_kern *ptr__uninit)
+ {
+ ...
+ }
+
+Here, the dynptr will be treated as an uninitialized dynptr. Without this
+annotation, the verifier will reject the program if the dynptr passed in is
+not initialized.
+
.. _BPF_kfunc_nodef:
2.3 Using an existing kernel function