selftests: net: fix error message in bpf_offload

JIRA: https://issues.redhat.com/browse/RHEL-84558
Upstream Status: net.git commit f9d2f5d

commit f9d2f5d
Author: Jakub Kicinski <kuba@kernel.org>
Date:   Tue Mar 4 15:32:03 2025 -0800

    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 <sdf@fomichev.me>
    Link: https://patch.msgid.link/20250304233204.1139251-1-kuba@kernel.org
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Hangbin Liu <haliu@redhat.com>

Author: Hangbin Liu

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))