selftests/bpf: fix netdevsim trap_flow_action_cookie read
When read netdevsim trap_flow_action_cookie, we need to init it first,
or we will get "Invalid argument" error.
Fixes: d3cbb907ae57 ("netdevsim: add ACL trap reporting cookie as a metadata")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/tools/testing/selftests/bpf/test_offload.py b/tools/testing/selftests/bpf/test_offload.py
index 8294ae3..43c9cda 100755
--- a/tools/testing/selftests/bpf/test_offload.py
+++ b/tools/testing/selftests/bpf/test_offload.py
@@ -318,6 +318,9 @@
continue
if os.path.isfile(p):
+ # We need to init trap_flow_action_cookie before read it
+ if f == "trap_flow_action_cookie":
+ cmd('echo deadbeef > %s/%s' % (path, f))
_, out = cmd('cat %s/%s' % (path, f))
dfs[f] = out.strip()
elif os.path.isdir(p):
