selftests: drivers: add scaffolding for Netlink tests in Python

Add drivers/net as a target for mixed-use tests.
The setup is expected to work similarly to the forwarding tests.
Since we only need one interface (unlike forwarding tests)
read the target device name from NETIF. If not present we'll
try to run the test against netdevsim.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 106 insertions, 0 deletions

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
new file mode 100644
index 000000000000..379cdb1960a7
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_INCLUDES := $(wildcard lib/py/*.py)
+
+TEST_PROGS := stats.py
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/drivers/net/README.rst b/tools/testing/selftests/drivers/net/README.rst
new file mode 100644
index 000000000000..5ef7c417d431
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/README.rst
@@ -0,0 +1,30 @@
+Running tests
+=============
+
+Tests are executed within kselftest framework like any other tests.
+By default tests execute against software drivers such as netdevsim.
+All tests must support running against a real device (SW-only tests
+should instead be placed in net/ or drivers/net/netdevsim, HW-only
+tests in drivers/net/hw).
+
+Set appropriate variables to point the tests at a real device.
+
+Variables
+=========
+
+Variables can be set in the environment or by creating a net.config
+file in the same directory as this README file. Example::
+
+  $ NETIF=eth0 ./some_test.sh
+
+or::
+
+  $ cat tools/testing/selftests/drivers/net/net.config
+  # Variable set in a file
+  NETIF=eth0
+
+NETIF
+~~~~~
+
+Name of the netdevice against which the test should be executed.
+When empty or not set software devices will be used.
diff --git a/tools/testing/selftests/drivers/net/lib/py/__init__.py b/tools/testing/selftests/drivers/net/lib/py/__init__.py
new file mode 100644
index 000000000000..4653dffcd962
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/lib/py/__init__.py
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+
+import sys
+from pathlib import Path
+
+KSFT_DIR = (Path(__file__).parent / "../../../..").resolve()
+
+try:
+    sys.path.append(KSFT_DIR.as_posix())
+    from net.lib.py import *
+except ModuleNotFoundError as e:
+    ksft_pr("Failed importing `net` library from kernel sources")
+    ksft_pr(str(e))
+    ktap_result(True, comment="SKIP")
+    sys.exit(4)
+
+from .env import *
diff --git a/tools/testing/selftests/drivers/net/lib/py/env.py b/tools/testing/selftests/drivers/net/lib/py/env.py
new file mode 100644
index 000000000000..e1abe9491daf
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/lib/py/env.py
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: GPL-2.0
+
+import os
+import shlex
+from pathlib import Path
+from lib.py import ip
+from lib.py import NetdevSimDev
+
+class NetDrvEnv:
+    def __init__(self, src_path):
+        self._ns = None
+
+        self.env = os.environ.copy()
+        self._load_env_file(src_path)
+
+        if 'NETIF' in self.env:
+            self.dev = ip("link show dev " + self.env['NETIF'], json=True)[0]
+        else:
+            self._ns = NetdevSimDev()
+            self.dev = self._ns.nsims[0].dev
+        self.ifindex = self.dev['ifindex']
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, ex_type, ex_value, ex_tb):
+        """
+        __exit__ gets called at the end of a "with" block.
+        """
+        self.__del__()
+
+    def __del__(self):
+        if self._ns:
+            self._ns.remove()
+            self._ns = None
+
+    def _load_env_file(self, src_path):
+        src_dir = Path(src_path).parent.resolve()
+        if not (src_dir / "net.config").exists():
+            return
+
+        lexer = shlex.shlex(open((src_dir / "net.config").as_posix(), 'r').read())
+        k = None
+        for token in lexer:
+            if k is None:
+                k = token
+                self.env[k] = ""
+            elif token == "=":
+                pass
+            else:
+                self.env[k] = token
+                k = None