[PATCH net-next] selftests: net: py: explicitly forbid multiple ksft_run() calls

[Jakub Kicinski <kuba@kernel.org>]

People (do people still write code or is it all AI?) seem to not
get that ksft_run() can only be called once. If we call it
multiple times KTAP parsers will likely cut off after the first
batch has finished.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: shuah@kernel.org
CC: petrm@nvidia.com
CC: willemb@google.com
CC: linux-kselftest@vger.kernel.org
---
 tools/testing/selftests/net/lib/py/ksft.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/lib/py/ksft.py b/tools/testing/selftests/net/lib/py/ksft.py
index 7b8af463e35d..7083c99c9444 100644
--- a/tools/testing/selftests/net/lib/py/ksft.py
+++ b/tools/testing/selftests/net/lib/py/ksft.py
@@ -341,10 +341,13 @@ KsftCaseFunction = namedtuple("KsftCaseFunction",
 
     totals = {"pass": 0, "fail": 0, "skip": 0, "xfail": 0}
 
+    global KSFT_RESULT
+    if KSFT_RESULT is not None:
+        raise RuntimeError("ksft_run() can't be called multiple times.")
+
     print("TAP version 13", flush=True)
     print("1.." + str(len(test_cases)), flush=True)
 
-    global KSFT_RESULT
     cnt = 0
     stop = False
     for func, args, name in test_cases:
-- 
2.53.0