selftests: net: fix error message in bpf_offload

We hit a following exception on timeout, nmaps is never set:

    Test bpftool bound info reporting (own ns)...
    Traceback (most recent call last):
      File "/home/virtme/testing-1/tools/testing/selftests/net/./bpf_offload.py", line 1128, in <module>
        check_dev_info(False, "")
      File "/home/virtme/testing-1/tools/testing/selftests/net/./bpf_offload.py", line 583, in check_dev_info
        maps = bpftool_map_list_wait(expected=2, ns=ns)
      File "/home/virtme/testing-1/tools/testing/selftests/net/./bpf_offload.py", line 215, in bpftool_map_list_wait
        raise Exception("Time out waiting for map counts to stabilize want %d, have %d" % (expected, nmaps))
    NameError: name 'nmaps' is not defined

Acked-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

tools/testing/selftests/net/bpf_offload.py

@@ -207,9 +207,11 @@ def bpftool_prog_list_wait(expected=0, n_retry=20):
     raise Exception("Time out waiting for program counts to stabilize want %d, have %d" % (expected, nprogs))
 
 def bpftool_map_list_wait(expected=0, n_retry=20, ns=""):
+    nmaps = None
     for i in range(n_retry):
         maps = bpftool_map_list(ns=ns)
-        if len(maps) == expected:
+        nmaps = len(maps)
+        if nmaps == expected:
             return maps
         time.sleep(0.05)
     raise Exception("Time out waiting for map counts to stabilize want %d, have %d" % (expected, nmaps))