[PATCH net-next v8 10/11] selftests: net: Add python context manager for netns entering

Xiao Liang
2025-01-13T14:39:05Z

Change netns of current thread and switch back on context exit.
For example:

with NetNSEnter("ns1"):
ip("link add dummy0 type dummy")

The command be executed in netns "ns1".

Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
---
tools/testing/selftests/net/lib/py/__init__.py | 2 +-
tools/testing/selftests/net/lib/py/netns.py | 18 ++++++++++++++++++
2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
index 54d8f5eba810..e2d6c7b63019 100644
--- a/tools/testing/selftests/net/lib/py/__init__.py
+++ b/tools/testing/selftests/net/lib/py/__init__.py
@@ -2,7 +2,7 @@

from .consts import KSRC
from .ksft import *
-from .netns import NetNS
+from .netns import NetNS, NetNSEnter
from .nsim import *
from .utils import *
from .ynl import NlError, YnlFamily, EthtoolFamily, NetdevFamily, RtnlFamily
diff --git a/tools/testing/selftests/net/lib/py/netns.py b/tools/testing/selftests/net/lib/py/netns.py
index ecff85f9074f..8e9317044eef 100644
--- a/tools/testing/selftests/net/lib/py/netns.py
+++ b/tools/testing/selftests/net/lib/py/netns.py
@@ -1,9 +1,12 @@
# SPDX-License-Identifier: GPL-2.0

from .utils import ip
+import ctypes
import random
import string

+libc = ctypes.cdll.LoadLibrary('libc.so.6')
+

class NetNS:
def __init__(self, name=None):
@@ -29,3 +32,18 @@ class NetNS:

def __repr__(self):
return f"NetNS({self.name})"
+
+
+class NetNSEnter:
+ def __init__(self, ns_name):
+ self.ns_path = f"/run/netns/{ns_name}"
+
+ def __enter__(self):
+ self.saved = open("/proc/thread-self/ns/net")
+ with open(self.ns_path) as ns_file:
+ libc.setns(ns_file.fileno(), 0)
+ return self
+
+ def __exit__(self, exc_type, exc_value, traceback):
+ libc.setns(self.saved.fileno(), 0)
+ self.saved.close()
--
2.47.1